How much variance in case weight is too much?

[barrysuperhawk]

Ive been loading fmj blasting rounds for 308 for a while, but I need to make a batch of more accurate rounds now. Since all of my brass is range or Gunshow pickup, finding enough of the same head stamp to even make a box of 50 is a challenge.

So, making the wild assumption that I could sort them by weight, I started checking my stash and I was shocked. I have weights from 150 grains to 200 for a single deprimed case. Most of my LC is around 175, but I don't have nearly enough of it.

Obviously zero variation would be best, but I am trying to make 1000+ rounds for 3 gun matches, and I am going to have to compromise a bit. So, what is an acceptable variation with these? If I stick between, say, 170 and 180 will I be good or is that too much?

FWIW I am feeding 6 rifles, FAL, 3X AR10, M1A & a savage bolt gun.

 

[TimeWillTell]

First, be careful shooting the same charges in mixed headstamp brass. There can be some very big differences in thickness that can cause large differences in pressure. This is the problem with mixed headstamp brass for accuracy (and potentially safety).

Have you prepped all the cases fully? Deprimed, clean, trim, (maybe even neck turn)? Its a tough proposition to get mixed headstamps to match up well for true accuracy. IMO if you really want to go for accurate reloads you probably need to buy some new brass. You can get 50 pieces of new winchester for about $20. Ideally for maximum accuracy you would buy a large number and weight sort those new winchester cases into lots by weight but that is more work and more money depending on your goals. Another option I like to do for my non-Lapua brass competition shooting is to buy once fired Federal Gold Medal Match brass. I actually just bought about 550 cases for $130 shipped from a Hide member. It isn't my comp ammo but I still will sort it into lots of 100 after I have fully prepped the brass.

As far as how much variation is too much variation, I honestly don't know. It all depends on your expectations from the ammo. I usually sort into groups that vary no more than 2-3 grains but I do a lot of case prep prior to this.

Hope this helps.

Also, do you plan to reload a specific load for each rifle, or just one load for all rifles? Case prep and careful charge weight measurement (ie, consistent charge weights) will be your best best for just general improvement in accuracy across a wide range of firearms. If you will be tailoring to an individual rifle that will involve a lot more to get very good reloads. Knowing your goals and expectations will probably help guide you in what is necessary and what is not.

 

[CharlieNC]

Water capacity (internal case volume) differs greatly. LC and FC are on the low end, while WC is high; this is nearly as important as the amount of powder in terms of pressure (safety) and velocity. If you load them based on the lower capacity LC you should be safe, but the velocities will not be very consistent for the others; ok for practice but not so good for matches. Like Time said, get enough of one thing for serious work. Once fired LC is not bad, and about as low cost as you can find.

You may be able to find a low charge node to minimize this for short range, but long range will suffer due to velocity differences.

 

[zipollini]

Most of the high power shooters that I have bumped into on other forums will sort fully prepped, same headstamp, matched brass into groups of +/- 1.0 grain.

 

[rduckwor]

Well, if you want true precision rounds, its time to buy some brass. You aren't likely to lose it and it works for a very long time if you take care of it, so that will take a bit of the sting out of the costs.

Lapua, Norma are favorites.

 

[barrysuperhawk]

Ok, some background and usage information: So far, for all of my semi automatic guns I have standardized on a 155 grain bullet and a couple of different powders. I really like bl-c2 but benchmark is growing on me. My bullet this time around is going to be Sierra 1255C (old) 155HPBT (not the new palma). This choice is because I picked up a gift cert for Sierra and have several thousand new, and have since picked up almost as many blems.

The last time I did this [before Obama], I loaded 2800 rounds in LC brass with BL-C(2) and 155 grain Hornady Amax bullets (another prize table pickup) at around 2700 FPS out of my 18" guns. I loaded until I ran out of bullets, and that has been my match ammo. Unfortunately I do use this in 3 gun matches, and it is very rare that I am able to pick it up, nevermind that both the FAL and the M1A each seem intent on tossing brass into the next county [and not even the same counties]. I found that SA surplus was very close to the same POI out to 200 or so, so I used it on the short range targets when I could, and made the "good stuff" last.

My old one size fits all load was a bit of a compromise because the neither the M1A or the FAL liked heavy bullets, and the AR pattern guns seemed to shoot everything well. All of my Guns are in the 16 to 18 inch range [except the 24" savage]. The savage bolt gun is the newest addition and that should allow me to gauge the relative accuracy of a batch but it's not a competition gun its just a range toy.

By the way who actually has Winchester 308 brass for 20 bucks a bag? I haven't seen it that cheap for a couple of years at least around here the places that have it want $35 a bag.

I have bought almost every bag of brass I have seen for sale, in the last 2 years except for the gun show commandoes that wanted $1 per piece of range pickup... This has netted me everything from RP BR brass [the lightest, in the 150 grain range] to some CBC brass that is 195-200 grains. The bit of LC that I have is fairly consistent at 175. I also have RWS, PPU, PMC, NK, WA that are each around 180 grains, except for the Small primer PPU that is 185+. I have even figured out that there is come berdan brass that I can use if I use primer sealant [nailpolish].

Now I just have to sort it out into what I use and what either becomes blasting/specialty lots or gets repackaged for sale.

 

[waveslayer]

From my experience it's neck tension and oal that effects accuracy the most. Try that and not to worry about case weight.

 

[Das Capitolin]

I think you are putting too much emphasis on case weight. The difference between a lightweight case and a heavier case with the same charge may only amount to an inch or less at 600 yards. There are several champion shooters the don't even sort their brass at all, and do extremely well in competition. Look to your barrel and action for accurizing a rifle.

 

[mark5pt56]

barrysuperhawk--check pm please.

 

[TimeWillTell]

Midway has winchester brass for $21 per 50. Out of stock now tho.

 

[bigedp51]

barrysuperhawk

I was given three five gallon buckets of .223/5.56 fired by our local police departments during one range outing. This averaged out to one bucket each of Remington, Federal and Lake City, so I ended up with "MIXED" brass with the same headstamps.
I tried sorting by weight, internal internal volume and neck thickness and it was a total waste of time. On impulse I picked up a box of Nosler custom brass that was weight sorted and preped by Nosler and this brass needed nothing done to it. If you visit the Accurate shooter website the majority of competitive shooters buy Lapua brass and do nothing to it. In three gun competition to save money they use Winchester brass because the chances of finding all your own brass is slim to none.

Bottom line, case weight has very little to do with case volume, buy new brass from the same lot and be done with it and you will have better consistency with your cases.

Trust me, there is nothing worse than weight sorting your brass, and then checking internal volume in grains of water and realizing your wasting your time. Below is a link to "Preparing Cases for Long-Range Accuracy" and they weight sort their cases, BUT one of the forum members made up internal volume charts and proved weight sorting has very little to do with internal case volume.

Complete Precision Case Prep within AccurateShooter.com

 

[Das Capitolin]

Then there's this: Litz Dominates His First-Ever F-TR Match with Pierce-Built Rifle « Daily Bulletin
From the article:

Bryan Litz shot his first F-TR match recently, and he came up a winner — a big winner. Competing at the Midwest Palma event, Bryan topped the F-TR field, winning by 15 points. In fact Bryan ended up finishing within 10 points of F-Open winner Alex Lipworth. In the 20-shot, 1000-yard matches, Bryan averaged an impressive 195-7X, with a stunning 196-11X score in one match. (Consider that the 1000-yard X-Ring is just five inches in diameter!) Not bad for Bryan’s first attempt at the F-TR game.

The only brass prep was mandreling the necks of the new brass for consistent neck tension. Bullets were slightly pointed, but nothing was segregated by weight, base-to-ogive, or anything. All the ammo I shot in Lodi was loaded in brand-new Lapua brass.

 

[mark5pt56]

I have a bunch of PMC listed if it helps anyone

 

[barrysuperhawk]

Ok, I get it. It just seemed that with a 40 grain variation in the weight of the brass kind of had to indicate a rather significant variation in internal volume and thus pressure. Since I have such wildly mixed headstamps [73 of this, 54 of that, 122 of something else] I thought that sorting them at least into weight ranges would allow me find "compatible brass" that should at least shoot close to the same.

First, be careful shooting the same charges in mixed headstamp brass. There can be some very big differences in thickness that can cause large differences in pressure. This is the problem with mixed headstamp brass for accuracy (and potentially safety).