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- The Conservative part of Ontario
Just something else to play with Here's the article.
http://home.comcast.net/~jesse99/sieving.html
[SIZE=+3]Sifting Powder for Better Performance[/SIZE]
In the April issue of Shooters New there was an article by Richard McQuisten on “Smokeless Powder Distribution Analysis” which I found very interesting. Mr. McQuisten wrote about some improvements he experienced in powder measurer consistency, muzzle velocity standard deviation reduction, and smaller group sizes after using powders, which were sieved. Well it all sounded to good to be true, but back my mind I remembered someone saying something about some benchrest shooters sifting their powders.
The timing of Mr. McQuisten’s April article was canny. I was in the process of building a 223-space gun and looking for information on loads for Sierra's 69 & 80 grain Matchkings™. At the time of the article all I had for my new gun was a 26 inch Krieger barrel, Accuracy Speaks Hand Guard, and a hand full of parts from Bushmaster. The Bushmaster DCM lower receiver was on its way, but the upper flattop receiver was on back order and not due until late July. Anyway I had plenty of time for a little research on loads for my new space gun.
I am one of those crazy guys, who believe in reducing as many variables as possible. Even if it’s very hard to quantify the improvements. I like reading the bench rest articles for things to make my Silhouette rifle and ammunition perform better. Currently I turn my case necks, deburr the inside flash hole, re-cut the primer pockets, re-cut the extractor grove, sort cases by weight, sort bullets by weight, and weigh each powder charge for my silhouette match ammo. My basic handloading belief and an important understanding for this article is, if you can divide any of the loading components in different piles and then use one of the piles it will have less variability and shoot better then randomly using the whole big pile. Some of things I do, can not be proven as to having any benefit in my silhouette gun or in any gun let along from the standing position. But I believe that if some little extra loading steps along the way make you feel better then you will shoot better. So Mr. McQuisten’s work of dividing or separating the gunpowder into different piles and then using the piles one at a time makes totally good since to me. Just how much will it really help and if I can measure any differences is the real question? Also shiny cases shoot better than dirty corroded ones.
That April article by Richard McQuisten just got me and I found myself studying gunpowder sizes and looking for sieves that could separate gunpowders. I concluded without any data or reading any studies that ball powders could be separated into different size groups much easier and with much greater precision than extruded or stick powders. The length of extruded powder kernels is normally about 1½ to 5 diameters long. Which makes the separation into different piles a little difficult. I find it hard to believe that powder sieves can separate the large diameter kernels from small diameter kernels while separating the long kernels from short kernels very effectively. But ball powders on the other hand are a natural for this process. Only problem, most say the extruded powders shoot better and are less temperature sensitive than ball powders. I am not one to disagree with this, basically all I have ever used for my twenty years of silhouette shooting has been DuPont’s now IMR 4064 Lincoln Logs. That is 43.0 grains of the stuff in Lake City cases. Pushing 180-grain old style and now new style Sierra Matchkings™. All is started with Federal 210M’s. So I am a good friend to one log powder.
Again, my interest in all of this gunpowder sifting stuff has been invigorated or initiated by the fact that I am building up that AR15 match long range rifle. The 223 Remington case is just to small to measure powder charges in my book and I am not going to compete with this rifle so I want the loading to be fast and effortless. My plan is just have fun with this AR-15 after the silhouette matches at Camp Grayling, Michigan. Mainly just shoot at things place on the chicken stands, at two meters, but I just can’t wait to see what it can do at 1000 yards with some 80-grain bullets. So who knows, maybe one of the ball powders will be just the ticket for my space gun. The high power guys that I shoot with in the winter indoor Southeast Michigan League with are great fans of Varget and Reloader 15 for their long range 80 grain bullets and Winchester 748 fans for their short range 69 grain bullets. I have some very limited experience with Winchester 748 only from using it for my 7mm TCU pistol. But more important I won a one pound can of Accurate Arms 2520 about ten years ago. After getting my 26 Krieger barrel in February and the back ordered upper flat top receiver from Bushmaster in late August. Which was completely after the 1998-shooting season, I had an abundance of time to read Black Magic, “The Ultra Accurate AR-15” by John Feamster and The Competitive AR-15 by Glen D. Zediker. Both very good books, especially if you are just seating around waiting for the parts to your first AR. Must tell you all a little secret, in early August after the Michigan State Silhouette Championship Matches and all the high power stuff at Camp Perry, I send an email to Quality Parts (Bushmaster). I told them what a great customer I am and how patience I have been waiting for my final Bushmaster part. Then I mention how nice it would be if they sent me a complementary case for my patience and being nice. Shortly after sending the email my flattop upper receiver came (about four weeks earlier than I had been told) followed by a free gun case a couple of days latter. It never hurts to ask.
As mention before, the process of separating gunpowder’s using the powder sieves should work better with ball powders than extruded powders unless the extruded powder length is the same as the extruded diameter. No proof just my feeling about this process and you can not argue feelings. I have been using Winchester 748 powder in my 7mm TCU pistol and I have some around to play with. Sierra claims that Win 748 is one of the accurate powders for the 233. So I may as well start my load development with some Winchester 748 and start to learn something about sorting or gunpowder sifting. I am thinking that I could use one size powder for the 69-grain bullets other size powder for the 80-grain bullets. The really big stuff and the really small stuff plus any other leftover powder sizes I will just use for my pistol loads. I don't do any competitive pistol shooting.
What I would like to do is divide the Winchester 748 ball powder into four unique piles:
Pile 1 - The big stuff, top 10% of the pile.
Pile 2 - The larger particle half, 40% of the pile.
Pile 3 - The smaller particle half, 40% of the pile.
Pile 4 - The crumbs, last 10% of the pile.
After looking over or studying Mr. McQuisten’s data, I decided on ordering 8-inch sieves in the following USA Series Sizes for sifting the Winchester 748-ball powder:
No. 25 - 0.027 in to catch the big stuff.
No. 35 - 0.0197 in to divide the pile.
No. 45 - 0.0139 in to catch and keep the small half.
Bottom Pan - to catch the crumbs.
Lid - just to top it off.
Well those two books on the AR-15 both mentioned something about the AA2520 powder every now and then. They did not ramp and rave about it, but mention AA2520 with possibilities. Remember my winning that can of powder, now I have a use for that one pound can of ten year old AA2520. Accurate Arms is a very thoughtful company by publishing the particle sizes for their gunpowder. So back to the April article and some not so careful studying on what size sieves are needed for working with AA2520 and Winchester 748 gunpowder. So my first guess with number 25, 30, and 45 sieves still looks good for the both powders. Good plan, now do it. Get the powder sieves.
I went to the Thompson Register and looked up sieves. Low and behold there are a lot of company’s making them. Now, would it ever be great, if I knew who the manufacturer was for the NECO moly bullet sieves. I have the NECO sieve system (cover, sieve, and bottom pan) for separating messy moly-coated bullets from messy moly-coated ball bearings. It works great, its well make, and has a great brass finish. I wrote down about six to ten manufacturers and phone numbers from the Thompson Register. The last one I wrote down was the first one I call, and it was Dual Manufacturing Co., Inc. in Chicago, Illinois. After a short introduction, I mentioned that I was looking for some standard height eight-inch sieves. After I mention that I wanted the ASTM-E-11 screen size number 25, 35, and 45. The reply from the other end of the phone call was. “Just what are you going to use them for? Gunpowder?” Heck, I had to say yes. About 45 minutes later, I got the instructions for ordering sieves. It was simple. Fax Dual [773]-267-4521 the sizes you want. When you get them and like them, pay Dual. Dual needs a piece of paper for the records. No problem, two days later I had my first three (#25, #35, & #45) sieves, bottom pan, and cover. One week later I had my fourth size #30 sieve, more on that later.
See Picture 1, picture of powder sieves from Dual and moly-bullet sieve set from NECO. There is a good reason that they look the same, so if anyone is looking for some powder sieves and wants the same quality as NECO moly-bullet sieves, call Dual [773]-267-4457 and get the same.
Side note: Cleaning the powder measure per old shooting articles does help. That gunpowder dust buildup in my Pacific Powder Measure looked like old dried up engine oil or grease. After cleaning and polishing the parts it operated much smoother. I now use a nice sloooow and smoooooth up and down stroke on the powder measure and it does make a difference. Yes, I weigh each of the silhouette match loads and I can tell or see the difference in weighing from a very clean and a not so clean powder measure.
The first sifting of the Winchester 748 and Accurate 2520 powders indicated that maybe the #30 sieve would also be very useful. So after ordering and receiving the #30 sieve I reran the powder collected on the # 35sieve over the #30 sieve. I also calculated the density for each the powders collected by screen size. See Table 1– Powder Sifting Results.
I am very proud these results. My screen size selection, after placing the second order, divided each of the two powders into nice discrete piles. The Winchester powder was split nicely into two piles with a little extra fine stuff being leftovers. The AA2520 ended up three discrete piles, one for the 80’s, one for the 69’s, and maybe one for the 308 or 53’s. So far things are looking pretty good. Sifting the powders was not hard. In fact it was much easier to by hand shaking than I thought it would be.
I simply pour the one pound can of powder on the top #25 sieve and wiggled the stack until all but a small remaining amount of gunpowder that will not pass through that #25 sieve is left on top of sieve screen. Then removed the sieve from the stack and bottled the powder caught on the #25 sieve. I then flipped the #25 sieve over and using an old “Oral-B Soft” toothbrush, I brushed the bottom side of the screen to remove any struck kernels. There will always be some little friendly kernels that try taking up permanent residence in one of the sieves screen holes. The little struck kernels were then saved and bottled as if they had not passed through that #25 screen size. Then #25 screen was retired since is work was completed.
Then I started to wiggle the now shorter stack (less the #25 sieve) of sieves until the powder seemed to stop flowing through the now #30 top screen. I then removed the #30 sieve and placed the captured powder in a mixing bowl. I normally would find the screen at this point heavily blinded or plugged. I then flipped the sieve over and using the same old toothbrush brush the bottom side of the screen and easily free all of those struck little kernels. Now those freshly little unstuck kernels were saved and bottled as if they had not passed through that screen size. Then I would replace #30 sieve back onto the top of the stack and pour the powder placed in the mixing bowl back into the #30 sieve and start wiggling again. I would continue the wiggling until the powder seemed to stop flowing. When I poured the powder from the top sieve into the mixing bowl and if the screen had only a few kernels struck in the #30 sieve, then I would save and bottle all the powder in the mixing bowl has powder captured on the #30 sieve. If the sieve was severely blinded or plugged with kernels, I would unplug them with the toothbrush, save them as being captured on that screen and repeat the process for the #30 sieve again and again. This would normally require unplugging the sieve about two to four times. After the #30 sieve was retired the process would be repeated for the #35 sieve and #45 sieve. The sifting process was easy and not dusty. Wiggling the stack of sieve is defined as having the pan in one hand with your other hand on the lid and shaking the stack of sieves until your arms are about to fall off or something like that.
The appearance of the Winchester 748 after sifting was not noticeably different. On the other hand, each pile of the Accurate Arms 2520 powder looked noticeably different. The difference was like looking at three piles of shot (#9, #7½, & #4). The three different sizes of the balls for the ball powder could easily be seen and why they call it ball powder. The sieved 2520 powder looked like little uniform ball bearings. The slight increase in powder density for both powders seems logical as the particle sizes get somewhat smaller. I should be able to get a little more powder by weight into the case if the holes between the particles are smaller and the powder weighs more than air. Both of the sieved powders ran well in my old pacific powder measure.
At this point, I still did not have all the parts for the rifle and was reading the books. So I loaded up 600 rounds using 24.5 grains of Winchester 748 with 69 grain Sierra Matchkings™. Also loaded up 200 rounds using 24.3 grains of AA2520 with 80 grain Sierra Matchkings™. The 69-grain bullet load should be a nice light to medium load for barrel break-in and general plinking. The 80-grain bullet load may be a cold day only load? Well time passed and the last part finally came. The rifle was finally assembled and now the fun could start.
The barrel break-in when just great. Shoot one round and clean barrel. Did that five times. Copper stopped after three rounds. Then five rounds and clean barrel. Again, there was no copper build-up. Then ten rounds and clean barrel and again no copper. Done with that breaking in.
Then some work to the Colt / B-Square scope mount, added a very small piece 0.030-inch shim stock and bondo to the rear scope ring and a little bondo to front scope ring. Now the scope is bedded and capable of the 1000-yard elevation angles. During my initial barrel break firings, I noticed that the rifle was having some cycling problems. The initial 100-yard groups with Winchester 748 were not very pleasing and hoping that will all change for the better when I get the gun cycling correctly. Eventually I found the cause of the cycling problem; the gas manifold was not seated fully against step in the barrel. This would cause some improper alignment in the gas ports as well as having the gas tube not fully seated in the bolt carrier. It had worked itself loose and started moving down the barrel until the bolt carrier or action stopped cycling. I can’t say the velocities are noticeably different if the bolt opens or not. That is also what one of those to books said about that subject. After the firing session which fixed the rifle, I went to a local gun show looking for things I did not know I needed. Well there was a good deal on some Accurate Arms 2520 so I got another pound to try. Now this was new stuff compared to my other pound. My old AA2520 was made in Israel and the newer powder was made in Czech Republic. That’s all you get from Accurate Arms for batch numbers unless the little store stuck on looking numbered label means something. So now I have another pound of AA2520 to sieve. I have sieved three cans of the Winchester 748 powder and all three were different batches. They all sieved to about the same percentages and densities. If I find the data I will added it here, if not you know why. On the other hand the Accurate Arms 2520 was different enough for me to notice in general appearance, percentages, and density. See Table 2– Powder Sifting Results, for my results on the second can of AA2520 and a can of Varget:
The general appearance of the AA2520 material from Czech Republic was not as uniform as my earlier can from Israel. After sifting the can from Israel most of the funny looking stuff (distressed powder kernels) were either with the small percent of large particles caught on the #25 screen or made there way down through all of the sieves to the bottom pan. The Israel AA2520 gunpowder captured on the #30, #35, and #45 screens looked very uniform. After sifting the can from the Czech Republic all the material collected on all the screen seem to have there fair share of funny looking particles. Overall the Czech gunpowder balls not appear as uniform or as round as the Israel gunpowder balls, for whatever that means.
Now for some loading and testing. I loaded up 100 rounds using Lake City cases and 100 Sierra Matchkings™ bullets. Each bullet weighing 68.9 grains. All primers will be from my new case of Winchester WSR primers. I have been shooting 69’s with 24.5 grains of 748 and not all that happy, but I have loaded 600 rounds, which are fine for some general plinking and off hand practice. I would like to try some Varget and AA2520 with some 69 Sierra’s. So I loaded up 100 rounds all using 24.5 grains of gunpowder and seated for 0.003 to 0.005 inches of bullet jump. The one hundred rounds were loaded as follows:
All the powder charges for these one hundred test rounds were checked and adjusted to be exactly 24.5 grains. I used a Mettler PE 360 electronic balance for this operation. I adjusted the Pacific powder measurer as necessary to be close to 24.5 grains. The electronic balance was zeroed with each empty case before adding the gunpowder charge to that case. Then weighing the case with the added gunpowder yielded the exact weight of the gunpowder put into case and measured to within 0.1 grain. The Varget loads were the easiest to adjust, just add or subtract a couple of the short little powder logs with a pair of tweezers. Five Varget logs per 0.1 grain of powder. The AA2520 was harder to adjust, but did not require much adjusting. The 2520 ball powder cycled through my powder measure very nicely. Any that were not exactly 24.5 grains on my scale were dumped and simply recharged. That process was easier and quicker than trying to catch or fetch small powder balls with a pair of tweezers. See Table 3– Pacific Powder Measurer Accuracy Results, for the tabulated results from weighing the one hundred test rounds and measurer statistics. See Table 4– Powder Density Results, for the tabulated results on powder density calculations. Each time I changed powders I would adjust the powder measurer for the new powder. After obtaining the correct powder measure setting and checking it a few times, than I would starting loading the 20 test rounds and recording the results.
I used the same case for determining the full water capacity and powder capacity of my 223 cases. I used the average of seven separate powder fillings. I was going to use the average from five readings but I saw more variability with the Czech Republic 2520 than I remembered with the Israel 2520. So I used seven, I would have used ten but run out paper space.
The Varget powder processed through my old Pacific Powder Measurer with a fine standard deviation of only 0.061 grains, while the AA2520 was 0.031 to 0.044 grains. My IMR 4064 is more like 0.23 grains so that Varget powder does measure well. I liked the looks of the Varget powder; the kernels appeared to be very uniform. I measured some just for the fun of it and the batch of Varget that I have, the kernels are about 1.55 mm long and 0.9 mm in diameter. I did notice that there were some smaller kernels mixed in. They measured 0.66 mm long and 0.62 mm in diameter. The small kernels would pass through the #25 sieve. I sieved the Varget powder after I made the 20 test loads. So the Varget is this test was not sieved for this first test firing, but the amount of the small kernels is very low (less than 0.1%). Again looking at the Varget kernel sizes, I do not believe you can get much culling of the Varget powder into different sizes groups, besides sorting out the very small stuff. But who knows?
So far I am beginning to like the Varget powder and shooting some will be the test. Shooting from a bench rest is not my most competitive position. But then I not much of a bench rest shooter. I do claim that my bench techniques are good for a solid three quarters of minute of angle. There is a lot more to good bench rest shooting than I understand and practice. Shooting this AR-15 from the bench so far as been very enjoyable. I have an old Wichita BR1000-1 Rest with a Sinclair Model 86 Rest Top. I use Protektor front and rear bags. I have installed a Hart Accuracy Asset to my AR1-15 to fit the 86 rest top for the bench testing. I modified the front hand stop bar nut, which stays inside the Accuracy Speaks Aluminum free-floating handguard, so I can remove the hand stop and install the Hart Asset and the bar nut stays in the handguard slot. See Picture 2, of rifle on rest.
The first time to the range for barrel break-in, I very quickly discovered that the rear sling swivel was a royal pain in the bag. That just had to go, so I made what I call my rear bag rider. Little aluminum tubing, little slice of channel iron, and some bondo; presto one rear bag rider. Works great, rifle holds elevation while moving it front to rear on the rest. See Picture 3, of rear bag rider.
Now to find out if sifting the gunpowder makes any difference? I have the one hundred rounds previously mention with Varget and AA2520. I also have another one hundred rounds using the Winchester 748 gunpowder. Each round has 24.5 grains of sieved (30-rds. with #30 sieve, 30-rds. with #35 sieve, & 40-rds. with #45) Winchester 748 powder and 68.9 Sierra’s. I was going to shoot twenty round of each and clean but my shooting time at the range was Saturday after a club high power match so my time was short but the conditions were great. Clear sky’s, no or very little wind, and temperature in the low 80’s. So opted to shoot ten of each load condition without any cleaning the different loads. I will just let the moly-bullets do there thing. All muzzle velocities were taken using an Oehler three-screen chronograph with the first screen ten feet from the muzzle. I found the test results very interesting. Up to now just about all I have fired in the space gun has been with 24.5 grains of Winchester 748 and 69-grain Sierra bullets. The groups have not been very good and ranging from 0.75 inch to 1.7 inches at 100 yards. But now the gas manifold is on correctly and the gun is working just great so it’s a fresh start. The plan will be to start this test using the last minute added Varget powder to settle the clean barrel with moly-bullets and then shoot test powders. The AA2520 non-sieved and sieved will be shot first, followed by the three sieved Winchester 748 gunpowder loads.
http://home.comcast.net/~jesse99/sieving.html
[SIZE=+3]Sifting Powder for Better Performance[/SIZE]
The timing of Mr. McQuisten’s April article was canny. I was in the process of building a 223-space gun and looking for information on loads for Sierra's 69 & 80 grain Matchkings™. At the time of the article all I had for my new gun was a 26 inch Krieger barrel, Accuracy Speaks Hand Guard, and a hand full of parts from Bushmaster. The Bushmaster DCM lower receiver was on its way, but the upper flattop receiver was on back order and not due until late July. Anyway I had plenty of time for a little research on loads for my new space gun.
I am one of those crazy guys, who believe in reducing as many variables as possible. Even if it’s very hard to quantify the improvements. I like reading the bench rest articles for things to make my Silhouette rifle and ammunition perform better. Currently I turn my case necks, deburr the inside flash hole, re-cut the primer pockets, re-cut the extractor grove, sort cases by weight, sort bullets by weight, and weigh each powder charge for my silhouette match ammo. My basic handloading belief and an important understanding for this article is, if you can divide any of the loading components in different piles and then use one of the piles it will have less variability and shoot better then randomly using the whole big pile. Some of things I do, can not be proven as to having any benefit in my silhouette gun or in any gun let along from the standing position. But I believe that if some little extra loading steps along the way make you feel better then you will shoot better. So Mr. McQuisten’s work of dividing or separating the gunpowder into different piles and then using the piles one at a time makes totally good since to me. Just how much will it really help and if I can measure any differences is the real question? Also shiny cases shoot better than dirty corroded ones.
That April article by Richard McQuisten just got me and I found myself studying gunpowder sizes and looking for sieves that could separate gunpowders. I concluded without any data or reading any studies that ball powders could be separated into different size groups much easier and with much greater precision than extruded or stick powders. The length of extruded powder kernels is normally about 1½ to 5 diameters long. Which makes the separation into different piles a little difficult. I find it hard to believe that powder sieves can separate the large diameter kernels from small diameter kernels while separating the long kernels from short kernels very effectively. But ball powders on the other hand are a natural for this process. Only problem, most say the extruded powders shoot better and are less temperature sensitive than ball powders. I am not one to disagree with this, basically all I have ever used for my twenty years of silhouette shooting has been DuPont’s now IMR 4064 Lincoln Logs. That is 43.0 grains of the stuff in Lake City cases. Pushing 180-grain old style and now new style Sierra Matchkings™. All is started with Federal 210M’s. So I am a good friend to one log powder.
Again, my interest in all of this gunpowder sifting stuff has been invigorated or initiated by the fact that I am building up that AR15 match long range rifle. The 223 Remington case is just to small to measure powder charges in my book and I am not going to compete with this rifle so I want the loading to be fast and effortless. My plan is just have fun with this AR-15 after the silhouette matches at Camp Grayling, Michigan. Mainly just shoot at things place on the chicken stands, at two meters, but I just can’t wait to see what it can do at 1000 yards with some 80-grain bullets. So who knows, maybe one of the ball powders will be just the ticket for my space gun. The high power guys that I shoot with in the winter indoor Southeast Michigan League with are great fans of Varget and Reloader 15 for their long range 80 grain bullets and Winchester 748 fans for their short range 69 grain bullets. I have some very limited experience with Winchester 748 only from using it for my 7mm TCU pistol. But more important I won a one pound can of Accurate Arms 2520 about ten years ago. After getting my 26 Krieger barrel in February and the back ordered upper flat top receiver from Bushmaster in late August. Which was completely after the 1998-shooting season, I had an abundance of time to read Black Magic, “The Ultra Accurate AR-15” by John Feamster and The Competitive AR-15 by Glen D. Zediker. Both very good books, especially if you are just seating around waiting for the parts to your first AR. Must tell you all a little secret, in early August after the Michigan State Silhouette Championship Matches and all the high power stuff at Camp Perry, I send an email to Quality Parts (Bushmaster). I told them what a great customer I am and how patience I have been waiting for my final Bushmaster part. Then I mention how nice it would be if they sent me a complementary case for my patience and being nice. Shortly after sending the email my flattop upper receiver came (about four weeks earlier than I had been told) followed by a free gun case a couple of days latter. It never hurts to ask.
As mention before, the process of separating gunpowder’s using the powder sieves should work better with ball powders than extruded powders unless the extruded powder length is the same as the extruded diameter. No proof just my feeling about this process and you can not argue feelings. I have been using Winchester 748 powder in my 7mm TCU pistol and I have some around to play with. Sierra claims that Win 748 is one of the accurate powders for the 233. So I may as well start my load development with some Winchester 748 and start to learn something about sorting or gunpowder sifting. I am thinking that I could use one size powder for the 69-grain bullets other size powder for the 80-grain bullets. The really big stuff and the really small stuff plus any other leftover powder sizes I will just use for my pistol loads. I don't do any competitive pistol shooting.
What I would like to do is divide the Winchester 748 ball powder into four unique piles:
Pile 1 - The big stuff, top 10% of the pile.
Pile 2 - The larger particle half, 40% of the pile.
Pile 3 - The smaller particle half, 40% of the pile.
Pile 4 - The crumbs, last 10% of the pile.
After looking over or studying Mr. McQuisten’s data, I decided on ordering 8-inch sieves in the following USA Series Sizes for sifting the Winchester 748-ball powder:
No. 25 - 0.027 in to catch the big stuff.
No. 35 - 0.0197 in to divide the pile.
No. 45 - 0.0139 in to catch and keep the small half.
Bottom Pan - to catch the crumbs.
Lid - just to top it off.
Well those two books on the AR-15 both mentioned something about the AA2520 powder every now and then. They did not ramp and rave about it, but mention AA2520 with possibilities. Remember my winning that can of powder, now I have a use for that one pound can of ten year old AA2520. Accurate Arms is a very thoughtful company by publishing the particle sizes for their gunpowder. So back to the April article and some not so careful studying on what size sieves are needed for working with AA2520 and Winchester 748 gunpowder. So my first guess with number 25, 30, and 45 sieves still looks good for the both powders. Good plan, now do it. Get the powder sieves.
I went to the Thompson Register and looked up sieves. Low and behold there are a lot of company’s making them. Now, would it ever be great, if I knew who the manufacturer was for the NECO moly bullet sieves. I have the NECO sieve system (cover, sieve, and bottom pan) for separating messy moly-coated bullets from messy moly-coated ball bearings. It works great, its well make, and has a great brass finish. I wrote down about six to ten manufacturers and phone numbers from the Thompson Register. The last one I wrote down was the first one I call, and it was Dual Manufacturing Co., Inc. in Chicago, Illinois. After a short introduction, I mentioned that I was looking for some standard height eight-inch sieves. After I mention that I wanted the ASTM-E-11 screen size number 25, 35, and 45. The reply from the other end of the phone call was. “Just what are you going to use them for? Gunpowder?” Heck, I had to say yes. About 45 minutes later, I got the instructions for ordering sieves. It was simple. Fax Dual [773]-267-4521 the sizes you want. When you get them and like them, pay Dual. Dual needs a piece of paper for the records. No problem, two days later I had my first three (#25, #35, & #45) sieves, bottom pan, and cover. One week later I had my fourth size #30 sieve, more on that later.
Side note: Cleaning the powder measure per old shooting articles does help. That gunpowder dust buildup in my Pacific Powder Measure looked like old dried up engine oil or grease. After cleaning and polishing the parts it operated much smoother. I now use a nice sloooow and smoooooth up and down stroke on the powder measure and it does make a difference. Yes, I weigh each of the silhouette match loads and I can tell or see the difference in weighing from a very clean and a not so clean powder measure.
The first sifting of the Winchester 748 and Accurate 2520 powders indicated that maybe the #30 sieve would also be very useful. So after ordering and receiving the #30 sieve I reran the powder collected on the # 35sieve over the #30 sieve. I also calculated the density for each the powders collected by screen size. See Table 1– Powder Sifting Results.
I am very proud these results. My screen size selection, after placing the second order, divided each of the two powders into nice discrete piles. The Winchester powder was split nicely into two piles with a little extra fine stuff being leftovers. The AA2520 ended up three discrete piles, one for the 80’s, one for the 69’s, and maybe one for the 308 or 53’s. So far things are looking pretty good. Sifting the powders was not hard. In fact it was much easier to by hand shaking than I thought it would be.
I simply pour the one pound can of powder on the top #25 sieve and wiggled the stack until all but a small remaining amount of gunpowder that will not pass through that #25 sieve is left on top of sieve screen. Then removed the sieve from the stack and bottled the powder caught on the #25 sieve. I then flipped the #25 sieve over and using an old “Oral-B Soft” toothbrush, I brushed the bottom side of the screen to remove any struck kernels. There will always be some little friendly kernels that try taking up permanent residence in one of the sieves screen holes. The little struck kernels were then saved and bottled as if they had not passed through that #25 screen size. Then #25 screen was retired since is work was completed.
Then I started to wiggle the now shorter stack (less the #25 sieve) of sieves until the powder seemed to stop flowing through the now #30 top screen. I then removed the #30 sieve and placed the captured powder in a mixing bowl. I normally would find the screen at this point heavily blinded or plugged. I then flipped the sieve over and using the same old toothbrush brush the bottom side of the screen and easily free all of those struck little kernels. Now those freshly little unstuck kernels were saved and bottled as if they had not passed through that screen size. Then I would replace #30 sieve back onto the top of the stack and pour the powder placed in the mixing bowl back into the #30 sieve and start wiggling again. I would continue the wiggling until the powder seemed to stop flowing. When I poured the powder from the top sieve into the mixing bowl and if the screen had only a few kernels struck in the #30 sieve, then I would save and bottle all the powder in the mixing bowl has powder captured on the #30 sieve. If the sieve was severely blinded or plugged with kernels, I would unplug them with the toothbrush, save them as being captured on that screen and repeat the process for the #30 sieve again and again. This would normally require unplugging the sieve about two to four times. After the #30 sieve was retired the process would be repeated for the #35 sieve and #45 sieve. The sifting process was easy and not dusty. Wiggling the stack of sieve is defined as having the pan in one hand with your other hand on the lid and shaking the stack of sieves until your arms are about to fall off or something like that.
The appearance of the Winchester 748 after sifting was not noticeably different. On the other hand, each pile of the Accurate Arms 2520 powder looked noticeably different. The difference was like looking at three piles of shot (#9, #7½, & #4). The three different sizes of the balls for the ball powder could easily be seen and why they call it ball powder. The sieved 2520 powder looked like little uniform ball bearings. The slight increase in powder density for both powders seems logical as the particle sizes get somewhat smaller. I should be able to get a little more powder by weight into the case if the holes between the particles are smaller and the powder weighs more than air. Both of the sieved powders ran well in my old pacific powder measure.
At this point, I still did not have all the parts for the rifle and was reading the books. So I loaded up 600 rounds using 24.5 grains of Winchester 748 with 69 grain Sierra Matchkings™. Also loaded up 200 rounds using 24.3 grains of AA2520 with 80 grain Sierra Matchkings™. The 69-grain bullet load should be a nice light to medium load for barrel break-in and general plinking. The 80-grain bullet load may be a cold day only load? Well time passed and the last part finally came. The rifle was finally assembled and now the fun could start.
The barrel break-in when just great. Shoot one round and clean barrel. Did that five times. Copper stopped after three rounds. Then five rounds and clean barrel. Again, there was no copper build-up. Then ten rounds and clean barrel and again no copper. Done with that breaking in.
Then some work to the Colt / B-Square scope mount, added a very small piece 0.030-inch shim stock and bondo to the rear scope ring and a little bondo to front scope ring. Now the scope is bedded and capable of the 1000-yard elevation angles. During my initial barrel break firings, I noticed that the rifle was having some cycling problems. The initial 100-yard groups with Winchester 748 were not very pleasing and hoping that will all change for the better when I get the gun cycling correctly. Eventually I found the cause of the cycling problem; the gas manifold was not seated fully against step in the barrel. This would cause some improper alignment in the gas ports as well as having the gas tube not fully seated in the bolt carrier. It had worked itself loose and started moving down the barrel until the bolt carrier or action stopped cycling. I can’t say the velocities are noticeably different if the bolt opens or not. That is also what one of those to books said about that subject. After the firing session which fixed the rifle, I went to a local gun show looking for things I did not know I needed. Well there was a good deal on some Accurate Arms 2520 so I got another pound to try. Now this was new stuff compared to my other pound. My old AA2520 was made in Israel and the newer powder was made in Czech Republic. That’s all you get from Accurate Arms for batch numbers unless the little store stuck on looking numbered label means something. So now I have another pound of AA2520 to sieve. I have sieved three cans of the Winchester 748 powder and all three were different batches. They all sieved to about the same percentages and densities. If I find the data I will added it here, if not you know why. On the other hand the Accurate Arms 2520 was different enough for me to notice in general appearance, percentages, and density. See Table 2– Powder Sifting Results, for my results on the second can of AA2520 and a can of Varget:
The general appearance of the AA2520 material from Czech Republic was not as uniform as my earlier can from Israel. After sifting the can from Israel most of the funny looking stuff (distressed powder kernels) were either with the small percent of large particles caught on the #25 screen or made there way down through all of the sieves to the bottom pan. The Israel AA2520 gunpowder captured on the #30, #35, and #45 screens looked very uniform. After sifting the can from the Czech Republic all the material collected on all the screen seem to have there fair share of funny looking particles. Overall the Czech gunpowder balls not appear as uniform or as round as the Israel gunpowder balls, for whatever that means.
Now for some loading and testing. I loaded up 100 rounds using Lake City cases and 100 Sierra Matchkings™ bullets. Each bullet weighing 68.9 grains. All primers will be from my new case of Winchester WSR primers. I have been shooting 69’s with 24.5 grains of 748 and not all that happy, but I have loaded 600 rounds, which are fine for some general plinking and off hand practice. I would like to try some Varget and AA2520 with some 69 Sierra’s. So I loaded up 100 rounds all using 24.5 grains of gunpowder and seated for 0.003 to 0.005 inches of bullet jump. The one hundred rounds were loaded as follows:
- 20 Rounds with 24.5 grains of Varget.
- 20 Rounds with 24.5 grains of AA2520 non-sieved.
- 20 Rounds with 24.5 grains of AA2520 #30 Between 710 & 600 microns
- 20 Rounds with 24.5 grains of AA2520 #35 Between 600 & 500 microns
- 20 Rounds with 24.5 grains of AA2520 #45 Between 500 & 355 microns
I used the same case for determining the full water capacity and powder capacity of my 223 cases. I used the average of seven separate powder fillings. I was going to use the average from five readings but I saw more variability with the Czech Republic 2520 than I remembered with the Israel 2520. So I used seven, I would have used ten but run out paper space.
The Varget powder processed through my old Pacific Powder Measurer with a fine standard deviation of only 0.061 grains, while the AA2520 was 0.031 to 0.044 grains. My IMR 4064 is more like 0.23 grains so that Varget powder does measure well. I liked the looks of the Varget powder; the kernels appeared to be very uniform. I measured some just for the fun of it and the batch of Varget that I have, the kernels are about 1.55 mm long and 0.9 mm in diameter. I did notice that there were some smaller kernels mixed in. They measured 0.66 mm long and 0.62 mm in diameter. The small kernels would pass through the #25 sieve. I sieved the Varget powder after I made the 20 test loads. So the Varget is this test was not sieved for this first test firing, but the amount of the small kernels is very low (less than 0.1%). Again looking at the Varget kernel sizes, I do not believe you can get much culling of the Varget powder into different sizes groups, besides sorting out the very small stuff. But who knows?
So far I am beginning to like the Varget powder and shooting some will be the test. Shooting from a bench rest is not my most competitive position. But then I not much of a bench rest shooter. I do claim that my bench techniques are good for a solid three quarters of minute of angle. There is a lot more to good bench rest shooting than I understand and practice. Shooting this AR-15 from the bench so far as been very enjoyable. I have an old Wichita BR1000-1 Rest with a Sinclair Model 86 Rest Top. I use Protektor front and rear bags. I have installed a Hart Accuracy Asset to my AR1-15 to fit the 86 rest top for the bench testing. I modified the front hand stop bar nut, which stays inside the Accuracy Speaks Aluminum free-floating handguard, so I can remove the hand stop and install the Hart Asset and the bar nut stays in the handguard slot. See Picture 2, of rifle on rest.
The first time to the range for barrel break-in, I very quickly discovered that the rear sling swivel was a royal pain in the bag. That just had to go, so I made what I call my rear bag rider. Little aluminum tubing, little slice of channel iron, and some bondo; presto one rear bag rider. Works great, rifle holds elevation while moving it front to rear on the rest. See Picture 3, of rear bag rider.
Now to find out if sifting the gunpowder makes any difference? I have the one hundred rounds previously mention with Varget and AA2520. I also have another one hundred rounds using the Winchester 748 gunpowder. Each round has 24.5 grains of sieved (30-rds. with #30 sieve, 30-rds. with #35 sieve, & 40-rds. with #45) Winchester 748 powder and 68.9 Sierra’s. I was going to shoot twenty round of each and clean but my shooting time at the range was Saturday after a club high power match so my time was short but the conditions were great. Clear sky’s, no or very little wind, and temperature in the low 80’s. So opted to shoot ten of each load condition without any cleaning the different loads. I will just let the moly-bullets do there thing. All muzzle velocities were taken using an Oehler three-screen chronograph with the first screen ten feet from the muzzle. I found the test results very interesting. Up to now just about all I have fired in the space gun has been with 24.5 grains of Winchester 748 and 69-grain Sierra bullets. The groups have not been very good and ranging from 0.75 inch to 1.7 inches at 100 yards. But now the gas manifold is on correctly and the gun is working just great so it’s a fresh start. The plan will be to start this test using the last minute added Varget powder to settle the clean barrel with moly-bullets and then shoot test powders. The AA2520 non-sieved and sieved will be shot first, followed by the three sieved Winchester 748 gunpowder loads.
