Some basic reflexions about rifle precision reloading

[Ron AKA]

Ron AKA, pardon any of my ignorance or what may seem obvious to everyone else regarding analysis of this graph but for clarity...
- the horizontal flat spots in the curves identify the optimum velocity for that rifle? (when graphing velocity vs. vertical)
- the optimum or sweet "velocity" is what is aimed for when swapping components there after (independent of component combination)

- I don't have a chronograph and just plotting powder charge vs. vertical on this end but a magnetospeed is in the future. I am trying to discern a correlation, in my mind, of relationships between graphs

It would be one of the optimum velocity sweet spots for that barrel/rifle combination. Things could change if you changed barrels, if that is what you mean by changing components. If you just mean changing primers or powder, or seating depth, then that velocity range should not be affected.

The next step after finding the optimum velocity would be to change the seating depth and base that on group size. Changing powder and primers have more of an effect on standard deviation and extreme spread. But while you are changing you want to keep the same velocity.

If by magnetospeed you mean one of those devices that attaches to the barrel to measure velocity, that will not work for doing a ladder test, unless you always want to shoot the gun with the device attached to your barrel. The vibration charateristics of your barrel will change from it being on and not.

 

[BCBRAD]

I generally try for OCW using Quickload , velocity is a product of the effort. Different powders can/will produce the same velocity but the gas produced by the burning powder accelerates at different velocities therefore can/will put you off a node, this is why one powder is preferred over another.

 

[Ganderite]

The trick is to find the load while the barrel still has some uiseful life left in it. In some calibers that is a real challenge. Some barrels only last 1000 shots.

 

[BCBRAD]

The trick is to find the load while the barrel still has some uiseful life left in it. In some calibers that is a real challenge. Some barrels only last 1000 shots.

With Quickload and a Labradar plus knowledge on the program it can be done in ~10 rounds.

Last May I wanted to use my 30-06 Finnlight at a local 1000 yard shoot, I had an M1 turret installed on the 6x42 Leupold. It has ~35moa on the erector, I want to hold on the crosshair of the reticle.

What bullet, what velocity to do this?

Searching bullet BC's found that a Berger 155.5gr Fullbore had the BC and the velocity ~2940ft/s to use up 31moa of erector travel.

I load 3 rounds and check velocity, found the predicted velocity was off of the actual, so I correct the burn rate of the powder (Ba) so predicted matched actual.

Loaded 5 rounds with 61gr of H-4350, at 100m <0.7" 5 shot group.

Load up 20 rounds and head to match. 7 5/8ths" 3 shot and 16 3/8ths" 5 shot groups at 1048 yards.

The load was definitely not a handi-cap as much as the Finnlight, 6X scope....a really hunting rifle that has banged around in the field and on the bars of a quad for years.

 

[RonR]

Try this for a graph.

Increase powder charge in small increments. Watch the group size and orientation change... when you find the two higher nodes where groups are smallest with the least amount of vertical dispersion, use the 2nd highest and that is pretty much it.

Jerry

Ahhh...thanks for the clarity and posting the graph Jerry.

Regards
Ron

 

[RonR]

The next step after finding the optimum velocity would be to change the seating depth and base that on group size. Changing powder and primers have more of an effect on standard deviation and extreme spread. But while you are changing you want to keep the same velocity.

If by magnetospeed you mean one of those devices that attaches to the barrel to measure velocity, that will not work for doing a ladder test, unless you always want to shoot the gun with the device attached to your barrel. The vibration charateristics of your barrel will change from it being on and not.

Changing seating depth is next to try for tuning. Noted on the magnetospeed. It will just be used to capture velocity independently by itself and other related calculations to audit the reloading process and component performance on this end.

Regards
Ron

 

[RonR]

I generally try for OCW using Quickload , velocity is a product of the effort. Different powders can/will produce the same velocity but the gas produced by the burning powder accelerates at different velocities therefore can/will put you off a node, this is why one powder is preferred over another.

This is what I am having trouble with. Acknowledged that there are similar burn rate/speed powders from different manufacturers but swapping out a powder for another to achieve the velocity sweet spot for my barrel, at least to me, would create a shift in accuracy or a node. But I'm going to test that...but first a purchase!.

Regards Brad
Ron

 

[Ron AKA]

Changing seating depth is next to try for tuning. Noted on the magnetospeed. It will just be used to capture velocity independently by itself and other related calculations to audit the reloading process and component performance on this end.

The problem with the Magnetospeed is that to do a proper Ladder Test you need to know the velocity of each bullet, and where that specific bullet impacts the target. The Magnetospeed does not allow you to do that. It is a poor idea to assume that if the powder charge is the same the velocity is the same. Unfortunately it does not work that way in real life. Here is a graph I did of actual measured velocity of the same bullet with varying charges of H322. As you can see there is a clear trend of increasing velocity with increasing powder charge. But, and it is a big but, individual bullets vary from the mean trend. When you do a proper Ladder Test you relate the actual velocity of that bullet to the actual POI on the target. The more shots you have the better it is, but a fairly low number will show you the sweet spot in most cases.

Incidentally I did abandon the H322 powder in favour of Varget. I found it was more predictable and achieved higher velocities. But, keep in mind that varying velocities does you no harm when Ladder Testing, as long as you know the velocity of each bullet. In fact it helps you better identify the sweet spot.

 

[Ron AKA]

This is what I am having trouble with. Acknowledged that there are similar burn rate/speed powders from different manufacturers but swapping out a powder for another to achieve the velocity sweet spot for my barrel, at least to me, would create a shift in accuracy or a node. But I'm going to test that...but first a purchase!

Perhaps I have not given the process a fair shake, but with what I see, I am not convinced the OCW process makes a ton of sense. First it does not use actual measured velocity. Yes, that is an advantage if you don't own a chronograph, but it does ignore very valuable data. QL claims to be able to predict when the bullet reaches the barrel muzzle, and if it really can then that would be very valuable. The chronograph method measures speed at the muzzle and uses that to imply barrel time (from fire to exit). With all due respect to computers, I think I would trust the measured velocity (providing you have verified your chronograph), over a computer calculation.

The bottom line is that I suspect the sweet spot velocity does not change significantly when you change powders and primers, or even bullets. It may change a small amount, but to confirm you are there after you develop a load with the powder, primer, and bullet you are happy with for SD and ES, all you have to do is repeat the Ladder Test, and make a small shift, if necessary.

I use the inexpensive Alpha Chrony and while I was initially skeptical of the accuracy and frequent dropped readings, I discovered these things are sensitive to muzzle blast. I borrowed another chrony and shot through them both at the same time. I found when I got them as far away as the cord would allow from the muzzle, they started to produce stable and essentially identical readings. My confidence in them was restored and I can recommend the product. I still do not trust the memory functions and simply record each velocity as I shoot it, as well as the point of impact on the target. A spotting scope and an assistant is really helpful for that...

 

[BCBRAD]

This is what I am having trouble with. Acknowledged that there are similar burn rate/speed powders from different manufacturers but swapping out a powder for another to achieve the velocity sweet spot for my barrel, at least to me, would create a shift in accuracy or a node. But I'm going to test that...but first a purchase!.

Regards Brad
Ron

The velocity sweet spot only relates to one powder of a given lot#. Which means that velocity, while close to a node may not be there with other powders producing the same velocity.

For example, one lot of H-4350 will give 2820 fps with 34grs of powder , the next lot may run 2820 fps but take 34.24 grains of powder. The powder is deemed 'slower' but the rate of acceleration of the gas column may differ thus altering the barrel time thus the position of the node.

Consuming all of the deterrent chemicals in the powder at peak pressure is desirable for a good stable load, OCW will indicate that.

 

[RonR]

Perhaps I have not given the process a fair shake, but with what I see, I am not convinced the OCW process makes a ton of sense. First it does not use actual measured velocity. Yes, that is an advantage if you don't own a chronograph, but it does ignore very valuable data. QL claims to be able to predict when the bullet reaches the barrel muzzle, and if it really can then that would be very valuable. The chronograph method measures speed at the muzzle and uses that to imply barrel time (from fire to exit). With all due respect to computers, I think I would trust the measured velocity (providing you have verified your chronograph), over a computer calculation.

The bottom line is that I suspect the sweet spot velocity does not change significantly when you change powders and primers, or even bullets. It may change a small amount, but to confirm you are there after you develop a load with the powder, primer, and bullet you are happy with for SD and ES, all you have to do is repeat the Ladder Test, and make a small shift, if necessary.

I use the inexpensive Alpha Chrony and while I was initially skeptical of the accuracy and frequent dropped readings, I discovered these things are sensitive to muzzle blast. I borrowed another chrony and shot through them both at the same time. I found when I got them as far away as the cord would allow from the muzzle, they started to produce stable and essentially identical readings. My confidence in them was restored and I can recommend the product. I still do not trust the memory functions and simply record each velocity as I shoot it, as well as the point of impact on the target. A spotting scope and an assistant is really helpful for that...

Hey Ron, very good information to digest.

I understand the value of obtaining correlating velocity data at the exact time of target results and it is noted that a magnetospeed and how it’s attached would have an effect on point of impact for a ladder test.

I’m definitely not an expert on internal or external ballistics by any stretch and don’t have a mechanical degree and that’s why I’ve posted and many such as yourself and BCBrad have answered previously. Perhaps I don’t comprehend all that has been stated but it seems that the sweet spot velocity is being chased in favour of the results on paper.

The approach here is have a forgiving load range that can provide allowances for minor variance changes i.e. cartridge capacity within one manufactures lots, deviation of bullets, primers etc. My understanding of the OCW method and the results here (when vertical variance is compared against powder charge) is that there is a charge within plus/minus .1 gr that provides repeatable accuracy ( less than .75 inch at 200 yds in our case. ) I believe that .1 gr powder charge variation should be able to account for many of the variables. For me it’s six sigma kind of thinking…where the limits are established and the process runs well within the curves so that the desired effect is guaranteed. <<< within reason of course…like how much coffee I’ve had that day.

Measuring velocity for our situation, in my opinion, is to strictly audit the reloading process. In this case I’m fine with shooting a few rounds after the fact to provide useful information about the process, and not the rifle. The rifle has spoken on paper. Excluding overpressure signs, it can’t tell me anymore.

For me it’s very difficult to fathom how to manipulate all the variables to achieve and maintain a repeatable velocity sweet spot. Unless there’s unlimited financial resources to keep all lots the same there would be at least one variable that would change. I would fear that if the velocity is not met, that something’s wrong…independent of what the paper is telling me.

Just my perspective. Great discussion Ron

Regards
Ronr

 

[Ron AKA]

Perhaps I don’t comprehend all that has been stated but it seems that the sweet spot velocity is being chased in favour of the results on paper.

The basic objective of the Ladder Test is to identify a range of velocities which have minimal to zero vertical impact. Nothing more. You can use powder weight instead of velocity, but it blunts the tool, as the same powder weight will give different velocities. The idea of the Ladder Test is to establish a target velocity for further testing. It is not the end of the road. You are using the paper to tell you what velocity works and what does not.

The OCW method I would describe as more of an organized blind trial and error method. If you are going to simply do trial and error as many shooters do, it is good to be organized so you don't go in circles. The OCW is as good a way to organize as any. I just don't think there is anything magic about it. It is basically, shoot lots of groups and decide which ones you like.

Aside from velocity, there are some general things you can do to make your load more "tolerant":

Powder - This is your basic control of velocity. You generally want the slowest powder that achieves your sweet spot velocity. Ideally you want the case close to full, full, or somewhat compressed. Hodgdon Extreme powders are very temperature insensitive. Many think that means they don't change velocity when the ambient temperature changes. But, there is more to it than that. Your cartridge "cooks" in the chamber while it sits there waiting for you to get organized and get the shot off. You can get erratic pressures and velocities if your cooking time of a temperature sensitive powder is erratic. See the link below for some interesting data. Of the top 100 shooters surveyed they all used Hodgdon Extreme powders!

Bullets - They can have one of the largest effects on accuracy. You need to find bullets that agree with your barrel twist, and throat dimensions. And there have been developments in the design of bullets to make them more tolerant to seating depth. Yes, you still need to shoot to determine the best depth, but they give you more tolerance, kind of like finding the velocity tolerance band. If you look at the survey at the link below, you will find that the Berger Hybrid bullet which has been designed to be seating depth tolerant is the most popular.

Primers - They are probably the biggest mystery of the consumable reloading components. A fellow in the US, by the name of German Salazar did some extensive testing and used to have a public blog with the full results. He has now made it a private blog, but you can find a few photos of the results of his testing here. The problem seems to be that there is no general consensus as to whether you want a big bang primer or a small bang primer. There are proponents of both schools of thought. However based on the same survey below CCI seems to dominate the choice of pros, with the exception of the Federal 210M in large rifle. And of course measuring velocity ES and SD can help with the selection of primers that are best for your powder and cartridge.

Reloading Components - What the Pros Use

So, I guess my point is that I find getting to the best load is done by looking at each issue independently and selecting the most tolerant velocity, bullets, and powder. Good groups will follow. You have to have some faith!

 

[bigbull]

I've been reloading cartridges for pistols and semi rifles for over 12 years now. Really in all that time I have never really worked loads extensively for precision. For example I would work up loads downwards for low recoil IPSC shooting, or upward for good magnum fireworks at the range, or else to obtain 3200fps on an AR, etc. but never loads for precision.

I have trouble with the idea of trying every possibilities by the tenth of grain for every single bullet type/weight i intend to shoot. To me it barely makes sense. Not only that but what about the compounding of human errors when you shoot? To you rifle old timers out there: How exactly do you determine that your rifle has hit a "sweet spot"? All comments will be appreciated.

Thanks.

Well...........Let me see where do we start!

You load for pistols and semi auto rifles and in 12 years you "never really worked loads extensively for precision", fair enough so you load for the savings I imagine.

Well if you are really serious about accuracy then your choice of firearms has to be rethought because you will have an impossible task trying to squeeze precision out of your type of guns.
A good bolt action rifle would be a better choice for a platform that will return some satisfaction for your efforts in the accuracy world.
I really want to help you but after trying for 12 years I believe you are on the wrong path and need to rethink your approach for accuracy and reloading.
Cheers
BB

 

[bigbull]

Doing the Audette Ladder Test is way simpler than it seems, and it is frequently misunderstood. All you are doing is finding a spot when the barrel is on an upward movement when the bullet exits. Fast bullets exit sooner when the barrel is pointed lower, and slow bullets exit later when the barrel is pointed higher. To find it you just shoot a number of bullets with stepped velocity and match every bullet hole to the velocity measured. Then you plot vertical elevation only vs velocity. You should get a graph like this:

You are looking for a velocity range where velocity is increasing but vertical elevation is not increasing, or perhaps even dipping a little. That is called the sweet spot. It is tolerant to small velocity changes with no or minimal impact on POI elevation. In the graph above of three different bullets the sweet spot is the same at about 3400-3420 fps. The true sweet spot is bullet weight and other components independent. It is purely dependent on your barrel and the velocity.

The next step after you identify the sweet spot is to vary seating depth, primer used, powder used, etc to minimize velocity extreme spread and standard deviation. Not too difficult if you are organized about it.

Ron,That is a great response I like the way you capture the whole procedure.
Thanks
BB

 

[BCBRAD]

I know this is not the end all- be all but finding the OCW has been made much easier by the use of LabRadar and the Quickload program.

Accurate velocities are the cornerstone , without the program will not be accurate.

Precise inputs are also essential.

The short of it is to have the selected powders progressive burning limit (z1) stop at peak pressure, this means that the deterrents in the powder (the chemicals which dictate the general burning rate) are all gone. If there are deterrents at play past peak pressure the powder is considered slow for the components involved. Expect lower ES, with no other changes, if z1 and Pm line up.

Next move is to get the bullet to exit on a node while still having the z1 line at peak pressure, if you can get this by manipulating powder charges or going to a different powder you will have a load that is tolerant and accurate with in the confines of the rifles mechanical ability.

This works for me, an example is the Tikka Tactical/ Vortex 4x16 PST (an off the shelf rifle with a YoDave spring installed) in 300 Win will hold slightly less than 0.4 moa to 1000 yards. I use a 208gr A-Max, H-1000, Federal standard match primers, annealed brass and ensure the cartridge is concentric.
Velocity is 2924 fps.

 

[curseyou]

The highest velocity accuracy node.

or the lowest reasonable accuracy load...

Highest is only for long distance. For those of us stuck at 300 it just burn the barrel quicker.

 

[skypilot]

or the lowest reasonable accuracy load...

Highest is only for long distance. For those of us stuck at 300 it just burn the barrel quicker.

I don't know, I'll take the higher speed( if you shoot movers or in high wind)it makes lead and wind call easier, but I get your valid point. I do still look for no vertical at load development ranges meaning at least 300m.

 

[MozPhoq]

I know this thread is cold, but I just wanted to thank all of you who put me on the right track with this ladder testing. Special thanks to RonR who was able to guide me in a snap.

I used what I learned on this thread today and found a sweet spot that gets me a half MOA constantly @300m with my Tikka. I'm very grateful.

 

[Ron AKA]

I know this thread is cold, but I just wanted to thank all of you who put me on the right track with this ladder testing. Special thanks to RonR who was able to guide me in a snap. I used what I learned on this thread today and found a sweet spot that gets me a half MOA constantly @300m with my Tikka. I'm very grateful.

Since this thread was active I stumbled on a Sierra blog site that gives a very good description on how to use the real Ladder Test followed by seating depth optimization. The only weak point of the article is that the author focuses on jam seating depths. A more thorough approach would be to consider both jam and jumps to find what your barrel likes. I suspect he already knew his gun liked a jam, and he was just trying to find the optimum jam.

Long Range Load Development - Sierra Bullets Product Development Manager Mark Walker

 

[RonR]

I know you've reloaded for much longer than I but it's got to feel good MozPhoq. I’ll be very truthful…I clover-leafed for the first time ever sighting in for hunting next weekend from a load developed using the OCW method and I’m new to this game as being my second reloading season. I certainly appreciate the feedback on your results.

I am not disputing ladder tests as a method to determine and accurate load or suggesting the OCW method is superior but this velocity thing…I can’t resist and am going to bite the hook…

Ron AKA I read that article you posted by Mark Walker of Sierra and I think it's contradictory to what you've posted.

In the first results Mark posts the velocity readings alongside an image of bullet holes. Note how there is no reference aiming mark to measure vertical differences? (no Y axis to use in your graph example to compare velocity vs elevation because there is no point to measure from. Actually a person can’t graph the first results because the graphs x axis would be of powder charge against the y axis subjective interpretation of flatter horizontal results <<< no values to graph) Further Mark didn’t get a velocity reading for the last shot and didn’t seem to care. Mark found 3 consecutive increasing loads that were flat relative to one another and chose the middle. "When picking a load, I am looking for the most shots at the same vertical location on the target…” later in the same paragraph “I settled on 54.5 grains as the load I wanted to use. It’s right in the middle of the group so if the velocity goes up or down slightly, the bullet should still hit in the same place on the target.” This relates to the objectives of the OCW method doesn’t it? and no relationship drawn to velocity by Mark.

A person could graph the second results as seating depth vs group size but there are no velocity results to match are there? A person can’t say that all the results in the second example of 54.5 gn of 4831 would be the same velocity from the first example.

My points are this
- Mark draws the relationship of powder charge and seating depth to arrive at an accurate round.
- Mark uses the results on paper (subjective interpretation not measurable results to graph) to arrive at an accurate charge load, not velocity as suggested
- Velocity readings can tell you a whole bunch, but to use velocity to as the datum to develop accuracy from is like chasing a f%^t in the wind.

I’ll stick to what I posted earlier that the rifle has spoken on paper. Excluding pressure signs it can’t tell me anymore. After reading this article, a chrony result won’t trump the group that’s been produced.
Regards
Ronr