When neck sizing with a bushing die, how much of the neck should be sized? A half? More? Less? I am having trouble with consistant velocity, and I think this, along with seating depth, may be part of the issue.
Thanks.
R.
Thanks.
R.
Question regarding neck size
- Thread starter Rman
- Start date
At a minimum, the part of the neck that corresponds with the bullet bearing surface. I goofed around with the micrometer seater and gave up on that. I size the whole thing.
More importantly, how much neck tension are you using? Velocity issues are less likely to be anything to do with how much neck is sized, but may be affected by differences in neck tension... are you detecting some bullets require more force than others to seat?
More importantly, how much neck tension are you using? Velocity issues are less likely to be anything to do with how much neck is sized, but may be affected by differences in neck tension... are you detecting some bullets require more force than others to seat?
- Location
- calgary alberta
I only size 1/2 way down the neck, but agree with Ian that inconsistant tension is a likely culprit.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
I recommend the whole neck be sized. Keeps from having chambering issues as the necks fatten.
What type of chronie? How's the battery? Light?
Most chronies have a 0.5% error in their clocks. That is a +/- 15 fps spread on a 3000fps reading.
I gave up using chronies to judge my ammo years ago. I now just use it to make sure I am not being a hero and about to blow myself to kingdom come.
I test at 200yds and let my groups tell me how my load tuning is working out. Works a whole lot better at LR.
Jerry
What type of chronie? How's the battery? Light?
Most chronies have a 0.5% error in their clocks. That is a +/- 15 fps spread on a 3000fps reading.
I gave up using chronies to judge my ammo years ago. I now just use it to make sure I am not being a hero and about to blow myself to kingdom come.
I test at 200yds and let my groups tell me how my load tuning is working out. Works a whole lot better at LR.
Jerry
I used to use a Full Length die to neck size by sizing the bearing surface of the neck without any problems, 223 Rem. I ran into a similar situation with velocity and accuracy inconsistencies with a bigger case, 300 winMag, while using a Lee collet die. Neck tesion was the culprit there, unable to uniformly size necks or depressed shoulders especially with nickel plated cases. Changed to Redding Neck dies, no more problems or guessing. As part of my case prep, all my cases are inside and outside neck turned to start with a uniform neck.
I definitely use a chrony to get me into the nodes. I discovered some stark differences with with varget by using the chrony and it put me into a whole new load ballpark to get the nodes that work.
Also, keeping the bullets as close to the sensors as practical makes a difference too. The "Chrony" brand has hinges in the middle, and if these are not set up perfecly flat, the sensor angles converge, meaning they will read high.
Try playing with one. The difference can be stark.
Also, keeping the bullets as close to the sensors as practical makes a difference too. The "Chrony" brand has hinges in the middle, and if these are not set up perfecly flat, the sensor angles converge, meaning they will read high.
Try playing with one. The difference can be stark.
Guy's, thanks for all of the info. I plan on doing some measurements shortly, and will have some better info to work with. We were testing .243AI loads, over a Chrony brand trap. I also shot some .338 loads over the exact same set up, and got very good results. This is what is pointing me towards the neck issue. I was using RL22, and it was fairly warm, but all things the same it should have been more consistant. Like I said, I will measure some necks, and get back to you with more info.
Thanks again!
R.
Thanks again!
R.
Fellas, I finally got around to measuring some necks. I am .273 in a loaded case, and
.276 in a fired case. This is pointing me, according to Redding's interweb site, to a .272 or a .271 bushing. The batch we ran through the chrony was necked sized at .268. Any further thoughts?
Thanks.
R.
.276 in a fired case. This is pointing me, according to Redding's interweb site, to a .272 or a .271 bushing. The batch we ran through the chrony was necked sized at .268. Any further thoughts?
Thanks.
R.
- Location
- Virden, MB
What is the neck wall thickness? What brass are you using?
What kind of chrony numbers are you getting ?
What are you using the weigh your powder and components?
What type of bullet? boat tail VLD, flat base?
If you have a miligram scale, you can geterdun with single digit FPS variation.
If you just have your typical hundred dollar one decimal place model, you will be hard pressed to get within 30 fps. The scale just cant throw any better than that.
Last edited:
.243 - .273 = .003/2 = .015
I have measured it with the mic., and as best I can tell, its .015. I am using both Lapua and Winchester brass, in two different rifles. Measurements are the same for both.
Thanks.
R.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
yep, 272 or 271 depending on spring back. single feed 1 thou is good. For mag feeding, I would go towards the 2 thou.
268 is way too much neck tension and could be part of your problem.
Let me know if you need bushings.
Jerry
Chrony velocity was spread between 1 fps and 30 fps over 20 rounds.
The same chrony, at the same time, measured a spread of only 6 fps, on the
.338 rounds. These rounds were not neck sized with a bushing die.
I use an RCBS electronic scale and powder measure combo, that is accurate to 1/10th of a grain.
Bullets are 105 A-Max moly coated.
I have loaded very accurate, and very consistant ammo before with my stuff, but this is the first time I have used neck bushing dies to size necks.
Thanks.
R.
Jerry, given our history, if I were to buy bushings from you, could you assure me that you didn't make them yourself, that they are indeed made of metal, and that they say Redding on the package, and not Savage?
R.
From what I see here, you are doing about as good as you can with what you have. Sometimes a guy can get a load over the chrony that looks real promising but it cant be repeated over a larger number of rounds.
The scale you have may claim to be accurate to 1/10th of a grain, but in reality I'd bet fifty bucks you could not produce 20 rounds in a row that are actually within that using stick powder. I have the same scale and have compared loads from it to my Sartorius miligram scale and I would not bet that the scale would be any better than plus or minus .3 grains - Thats a minimum total variation of over a half grain. Furthermore, you cannot weigh any of your components any better than that either so weight sorting is almost a waist of time.
Dismissing the keyboard experts out there with outrageous claims of consistancy - you have come upon the reality of what can be done if you omit luck and coincidence.
To get consistant single digit chrony results you will need a miligram scale and weight sort everything.
Some guys with large case capacity like good firm but consistant neck tension so thay can jam the lands hard. The idea is that you use the bullet to plug the hole to prevent pressure leaking past the bullet - and that suposedly results in more even velocity.
I personally preffer the opposite. I like to seat bullets long with very light neck tension and soft seat them into the lands upon chambering. My thinking is that the total variation in neck tension must be less if there is less neck tension in the first place and I can chase throught erosion.
On the other hand the winner of the 2010 ORA match last weekend jumped his bullets almost .1" with a 7MM.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
Jerry, given our history, if I were to buy bushings from you, could you assure me that you didn't make them yourself, that they are indeed made of metal, and that they say Redding on the package, and not Savage?
R.
I promise they will come in a package with a Redding lable.
Now to go find the box of washers and a hammer
Send me a PM and we can get you dialed in. Next booking closes today so we best get moving.
What you need to decide on is Steel or Ti coated bushings? Steel is less money, more hassle to use. Everyone that goes Ti coated, don't go back to steel.
Jerry
