Reloading for lowest Standard Deviation

[nated]

What are the steps you go through to lower your standard deviation when selecting a load to compete with? If this has been addressed, beaten to death in another thread point me over there. Thanks

 

[DLH_]

This is something that comes up very often and there’s not particularly a set answer. However, the main area to focus on in my experience is consistent neck tension. Neck turn, use a bushing sizing die without an expander ball and experiment with different levels of neck tension. Many sing the praises of annealing, I on the other hand tend not to be such firm believer in its effectiveness. Nonetheless, I’d suggest trying it if all else fails.

Josh

 

[Ned Ludd]

Consistent brass prep, optimized and consistent charge weight, consistent neck tension, appropriate burn rate powder for the bullet/caliber you're using, appropriate primer. Many of these variables can only be determined (optimized) empirically, but they are all potential factors in velocity variance. The key word is consistency; the best you can generate with the equipment you have, in as many facets of the reloading process as possible. As you gain more experience, you'll develop a better "feel" for the relative importance of the different variables. Obviously, some variables such as consistent neck tension and charge weight should be at the top of the list. However, the combined effect of several items that individually may make a lesser contribution to velocity variance can still be additive, and together may cause a more noticeable issue.

 

[nated]

How does one test primer, powder combinations for lowest Stand Deviation? I'm shooting 10 rounds of each combo through a clean barrel with the same powder charge, so H4350 at X charge and y different primers. thanks

 

[dmoran]

For LR & ELR, personally care far more about vertical dispersion (at distance), then I do about velocity or SD.
The loads with the least amount of vertical, make the smallest groups on the targets.
The loads with the least amount of SD, look the best on paper/computer, but not always on the targets.
My 2-cents

 

[Mulligan]

Consistent brass prep, optimized and consistent charge weight, consistent neck tension, appropriate burn rate powder for the bullet/caliber you're using, appropriate primer. Many of these variables can only be determined (optimized) empirically, but they are all potential factors in velocity variance. The key word is consistency; the best you can generate with the equipment you have, in as many facets of the reloading process as possible. As you gain more experience, you'll develop a better "feel" for the relative importance of the different variables. Obviously, some variables such as consistent neck tension and charge weight should be at the top of the list. However, the combined effect of several items that individually may make a lesser contribution to velocity variance can still be additive, and together may cause a more noticeable issue.

Other things to add to the good list above;

How the gun is handled effects velocity.
In my testing free recoil will produce a bit lower velocity than a firm hold.

Case capacity also will also have an effect on this.

CW

 

[_Raining]

In my testing free recoil will produce a bit lower velocity than a firm hold.

It is interesting that you say that, I just read over this article today:
https://blog.ammolytics.com/2018-12-12/experiment-recoil-vs-muzzle-velocity.html

 

[BoydAllen]

It is interesting that you say that, I just read over this article today:
https://blog.ammolytics.com/2018-12-12/experiment-recoil-vs-muzzle-velocity.html

I looked the article over and it is fundamentally flawed. He uses a Harris bipod on a concrete bench for both shouldered and free recoil shooting. This does not correspond to the common definition at all. Too bad.

 

[_Raining]

I looked the article over and it is fundamentally flawed. He uses a Harris bipod on a concrete bench for both shouldered and free recoil shooting. This does not correspond to the common definition at all. Too bad.

• Preloaded Bipod string: I pressed the bipod tightly against a solid surface (some 2x4s strapped to the bench).
• Free-Recoil string: I used an F-class style front rest to safely fire without mitigating any recoil.

I had suggested he try preloading the front stop of the rest instead of using the bipod so that there would be less variables in the friction differences of a bipod (rocking) vs a front bag (Sliding), IDK if he will be redoing this test anytime soon.

 

[BoydAllen]

• Preloaded Bipod string: I pressed the bipod tightly against a solid surface (some 2x4s strapped to the bench).
• Free-Recoil string: I used an F-class style front rest to safely fire without mitigating any recoil.

I had suggested he try preloading the front stop of the rest instead of using the bipod so that there would be less variables in the friction differences of a bipod (rocking) vs a front bag (Sliding), IDK if he will be redoing this test anytime soon.

My bad. Good catch. That is what skimming too fast can result in. It would be interesting to see the same test done with a lighter caliber, using competition benchrest equipment. The rifles slide quite a bit more freely, and when I am holding a hard kicker, I think that I have quite a bit more pull from pistol grip into my shoulder than is required to preload a Harris bipod. His test does seem to correspond to the one he is challenging.

 

[dmoran]

From a benchrest rifle chambered in 6mmBRA, Panda action, Krieger barrel, Tom Mousel tested the fallowing 3 rifle holds with 22-shots fired to each position (66-shots total) <> Labradar (22-shot velocity averages):

• 2672-fps - Free-recoil
• 2670-fps - Light hand and shoulder contact
• 2672-fps - Aggressive hand and shoulder contact

 

[BoydAllen]

From a benchrest rifle chambered in 6mmBRA, Panda action, Krieger barrel, with fire-forming loads, Tom Mousel tested the fallowing 3 rifle holds with 22-shots fired to each position (66-shots total) from a Labradar, (22-shot velocity averages):

• 2672-fps - Free-recoil
• 2670-fps - Light hand and shoulder contact
• 2672-fps - Aggressive hand and shoulder contact

Thanks for sharing that. It figures; he does a lot of testing, of anything that you can think of.

 

[dmoran]

Thanks for sharing that. It figures; he does a lot of testing, of anything that you can think of.

Yes he does.... but as you may have noticed, he quite posting and sharing his test results/methods (to many experts). I had asked him to conduct that one for me, which he did while fire-forming (perfect time to test many aspects from a single/same load).

 

[Mulligan]

Yes he does...... but as you may have noticed, he quite posting and sharing his test results/methods (to many experts ..... lol).
I had asked him to conduct that one for me, which he did and fit into a fire-forming session (perfect time to test many aspects).

I have noticed a couple of the folks from the Big Sky country that many of us have respect for have vanished off this forum...
Lessons the value by some margin. IMO

CW

 

[rammac]

I suspect that it's not that there are too many "experts" but rather there are too many jerks that don't show any respect to others. Internet forums are full of angry, nasty, people that like to stir up crap rather than just say "I disagree and here's why...".

 

[Bart B.]

A few have eliminated all the rifle holding variables by bolting the barreled action to a board clamped on a bench top so it doesn't recoil back during barrel time. This gives the best velocity ES and SD numbers as far as components go. They'll be a little different than the rifle free recoiling on bags or shouldered; sometimes a lot different.

The best load for ES and SD minimum may not produce best accuracy.

 

[dminn1]

Yes he does.... but as you may have noticed, he quite posting and sharing his test results/methods (to many experts).
I had asked him to conduct that one for me, which he did while fire-forming (perfect time to test many aspects from a single/same load).

Definitely noticed he has not been posting. One of the most knowledgeable shooters on here. Always liked his and your posts.

 

[centershot]

I always shoot for accuracy first. If it comes in at a good s d, than better yet.

 

[6MMsteve]

For LR & ELR, personally care far more about vertical dispersion (at distance), then I do about velocity or SD.
The loads with the least amount of vertical, make the smallest groups on the targets.
The loads with the least amount of SD, look the best on paper/computer, but not always on the targets.
My 2-cents

testing on paper at range is IMHO the best....I concur

 

[ppaul]

Yes he does.... but as you may have noticed, he quite posting and sharing his test results/methods (to many experts).
I had asked him to conduct that one for me, which he did while fire-forming (perfect time to test many aspects from a single/same load).

I have noticed some very respected shooters have quit posting, that's a shame. I for one have learned a lot on this forum. I'm mostly silent just trying to absorb the content. The most useful point is to test,test,and test. There is much to be said for learning by doing. Now if these below zero temps would leave.

A sincere thank you from this corner,

Paul