Strategy for prioritizing variables?...

[entoptics]

Ideally, I'd like to see quantitative data, but I know how forums and the interwebs work, so anecdotal commentary is welcome too.

As a reloader/shooter, do any of you have data to prove what variables make the biggest difference in your precision? I have the tools to measure all sorts of stuff, but it's very difficult to prove the effectiveness of minimizing particular variance, and the time involved would be prohibitive to anyone but an ammo company.

How would you rank the following measurements, in terms of how they affect precision in a quality rifle setup.

1) Runout/Concentricity
2) Powder weight (obviously not talking "two teaspoons", but within reason on a consumer grade scale)
3) Brass trim length
4) Bullet seating depth
5) Brass volume consistency (i.e. brass weight sorting)
6) Bullet sorting

Obviously, I understand that wind and shooter skill dominate the above variables, but I consider myself pretty steady. I can hold my reticle within a 1/4 MOA from my makeshift "wheat field prone bench", but my groups tend to be 3-5 times that with my new barrel, even on dead calm days.

I'm curious to hear what variables you all think are worth focusing on, so I can feel confident that I've addressed the "worst case scenario" as I go forward with practice. I'm happy with 1 MOA in my hunting rig, but if I could spend a little time in my shop to shave some off, I'd be willing to do it, but figuring out what to obsess over is tough without an unlimited budget...

 

[User4302021]

For longrange precision shooters, neck tension is the biggest variable in an otherwise precisely crafted load.

 

[Deputy819]

I hunt with a .338-06 that seems to be tolerant of minor handloading "imperfections" with the exception of concentricity. .001-.003 runout is okay with it, but it will throw ANYTHING above .003 runout WAY OUT of the group. In 6mm's that I've loaded for neck tension AND seating depth seem to be the things that affect my precision the most.

 

[RockyMtnMT]

For me and what we do the easiest one to control that makes a big difference is the powder charge. I personally hate the monotony of sorting components so I try to use components that do not need sorted. I would say that brass volume is a real culprit to inconsistent pressure. As a bullet maker I have to say that consistent bullets are a huge deal. Because of our bullets the other things on your list become much less important.

Left out of your equation is the rifle. Exceptionally well built rifles overcome much of your list.

Steve

 

[gohring3006]

First start out with a rifle capable of precise shooting, then a capable scope.
Second is the shooter being capable.
Third would be consistent brass and bullets.
Then use a stable powder.
Then I correct runout.
Then I load for low ES and SD.

 

[Greyfox]

In general, components(brass, bullets, brass, primers, powder) are chosen for well established constancy and quality). In terms of my priority in terms of developing loads and priority, I tend to rate the influence on the performance of my loads as follows:
-Bullet
-Powder
-Powder charge weight
-Primer brand/type
When possible, my starting point is the result of researching loads for the bullet type I'm interested in, and to replicate loads that proven out with multiple shooters. I'll then tune from there. I'm pretty meticulous about case length trimming, and use either Lapua or Norma brass for its consistency. Neck tension usually runs .002 +/- .0005". Powder charges are weighed to .1gr. I will start with Match grade primers, Federal or CCI. My runouts, using Redding S Dyes will run under .002". The standard of performance for my LRH rifles is <.5MOA with ES <15FPS. Temperature stability from 20F-80F.

 

[Mikecr]

Seating depth is largest.
Then primer/ seating/ striking
Then powder type
Powder amount
Bullet stability (while marginal at least)
Then case to chamber fit (how much case expansion, any chambered tensions)
Then case volume
Neck tension is near least -barring a tension problem
Chamber end clearance(from trim length)
Runout affects are tied to chamber fit
Bullet diameter, and meplat diameter

 

[entoptics]

Thanks for the tips, although it seems a bit like I expected...Everyone has a slightly different opinion on priority order.

For perspective, my rifle is a Savage LRH 300 WM with a Shilen Select SS barrel. Other than the barrel, it's bone stock. Scope is a Sig Tango4 6-24. Brass is neck turned Norma (± 1% weight spread total, usually sorted into 0.25% groups). Necks aren't all the same length, as it arrived WAY short, and the forum advised me not to trim them all to the shortest, but I sort it into batches of ±0.001" for loading anyway. Powder is hand weighed to ±0.000, so only error there is in the scale.

I'm now about 25 groups into load development, and my spreadsheet says 1.01 MOA overall average of 4 shot groups. The reason I asked about loads, is the "minus flier" (best 3 of 4) column says 0.53 MOA. Seems like I get an awful lot of tiny 3 shot groups with an ugly flier. The rifle also doesn't seem to really like any particular seating depth or bullet. I only run the 210 class, and have tried ELDM, ELDX, Berger VLDH, and Nosler ABLR in 0.03" increments from touching the lands to 0.09 off. As an example, the ELDM has printed a 0.6, 0.8, and 1.1 MOA group, all at 0.030". Similar results for everything else give or take a tenth of an MOA.

I think I'm gonna quit chasing "perfection", as my hand loads are probably not the limiting factor achieving "all day long" 3/4 MOA shooting. Perhaps it's the stock, perhaps the shooter. Either way, I'm gonna take 1 MOA "all day long" and call it good. Time to start learning the wind better so I can take full advantage of my 1 MOA in breezy wheat fields.

On the bright side, I just eliminated runout in my seating die. Not sure how. I've tried all the standard tricks before, and still commonly ended up with 30% of my rounds well outside 0.002", with far too many ≥0.004". Last 32 rounds I loaded, 2 of them had ≥0.0015. Now I'm afraid to take the die out of the press...

 

[Rich Coyle]

Once you settle on a load try different primers. They some time cut groups in half! No particular brand seems to come out on top in my shooting.