Reloading .308 cases for second time [Archive] - Glock Talk

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pilon_mn
08-09-2009, 15:29
Hey All -
I've more or less perfected my load based on _new_ brass and my .308 is shooting sub 1/3MOA. I'm half way through fire forming 500 rounds and am starting to think about the second time through the press. I have my neck sizing die that I plan to use with limited or no shoulder bump.

my question is - should I plan to rework the load for the second/subsequent loads or is there a consensus that the initial load is pretty much just as accurate (or more so) once the cases are fire formed.

if it matters - shooting out of a .308Win Savage 10FP, cases are/were new Remington.

-cjp

Myke_Hart
08-09-2009, 18:03
The second time around the brass will be more accurate.

If you can neck size only, the case will be fire formed to your camber. Most loaders will fire form the brass before starting to work on perfecting their accuracy load.

There is a awesome article on Developing .308 load that tested this theory in handloader magazine December- January by Gary D Sciuchetti.

First firing was not very accurate (4 inch group), second firing was spot on (1 inch group). Just fictitious numbers, they were reduced by a decent percent.

They also testing the logevity of the brass. The results were surprising!

www.handloadermagazine.com

pilon_mn
08-09-2009, 18:20
The second time around the brass will be more accurate.


Myke -
Thanks for the quick reply - with the rifle already doing sub 1/3MOA with new brass (trimmed the brass and FL resized them for uniformity)...getting more accurate is going to be interesting - and will probably demonstrate the weakness of the shooter more so than the machine.

fredj338
08-09-2009, 20:40
The second time around the brass will be more accurate.

If you can neck size only, the case will be fire formed to your camber. Most loaders will fire form the brass before starting to work on perfecting their accuracy load.

There is a awesome article on Developing .308 load that tested this theory in handloader magazine December- January by Gary D Sciuchetti.

First firing was not very accurate (4 inch group), second firing was spot on (1 inch group).

They also testing the logevity of the brass. The results were surprising!

www.handloadermagazine.com

I can't imagine fireforming making a 3moa diff in accuracy, never seen it. Yes, my groups will be slightly smaller w/ the fireformed & neck sized brass but @ 1/3moa, the group size is now more on the shooter IMO. If you have amatch cut chamber, your brass isn't going to stretch much anyway.:dunno:

Myke_Hart
08-10-2009, 05:07
I didn't believe it either. But he has picture and data proof for each type of brass tested.

Just looking at the charts for virgin brass, the average group size was over .5 an inch. After that fire forming they were neck sized and most of them averaged below .5 an inch. And all groups shrank on all brass types for all manufacturers. Some granted only shrank by a tiny bit some shrank a lot.

You have to check out the article and you will see the results for yourself. He fires new brass without resizing, then neck sizes it. The groups shrink 22percent on average.

There is also a brass logevity test he does. Fires all brass until it fails. The results here are surprising as well. Most of the expensive brass failed early. While others went out to 24 reloads.

In his tests he starts off with a Rem VLS 700 and then chucks it for a Sako TRG-22 because the Remington was not accurate enough to see results.

He does this with all major brands of brass as well.


What is the legality of PDF'ing the article and posting it here so you guys can read it?

Myke_Hart
08-10-2009, 05:17
I can't imagine fireforming making a 3moa diff in accuracy, never seen it. Yes, my groups will be slightly smaller w/ the fireformed & neck sized brass but @ 1/3moa, the group size is now more on the shooter IMO. If you have amatch cut chamber, your brass isn't going to stretch much anyway.:dunno:

Sorry, I was trying to write from memory.
My numbers were fictitous (4inch to 1 inch).
I looked up the article and I should have used .5 inch for virgin and .3 inch groups for formfired neck sized. But in all there was always a significant decrease.

I suppose 4 and 1 would be somewhat true at a greater distance. or more like 4inch and 1.5 inch. :supergrin:

Groups are like fish stories, they get better the more they are talked abou!:embarassed:

pilon_mn
08-10-2009, 07:33
Groups are like fish stories, they get better the more they are talked about!

i hear yah - the day i shot a .6" group at 200 yds, a gal newbie we brought along shot a one holer. She didn't seem to get the importance until all the old guys at the range started gawking (not at her, but at her target).

I sent the target home with her...in retrospect, probably should have made a copy to avoid the claims of ever shrinking groups... ;)

pilon_mn
04-03-2010, 07:20
just came back to this message and forgot to ask... has anyone had the experience of having to re-tinker the charge wt on subsequent loads? or just size 'em and go?

Hoser
04-03-2010, 09:08
After you first loading you should only need to neck size. If the bolt gets hard to close after a few reloads, you might need to bump the shoulder back a touch.

Your powder charge should be close, within 0.2 or so, to your old pet load.

Three-Five-Seven
04-03-2010, 09:18
A chronograph is the best (only) way to answer your question.

Obviously, you'll have cases with greater volume after fire forming them. Whether the load gets more, or less, consistent in the "new" sized cases is probably a 50/50 proposition. A chrono will tell you if the variation (spread, or standard deviation if you want to do the math) changes before and after forming.

Without a chrono, there's no way to know what the effect of changing case volume will be for a given load.

Since you're already shooting 1/3 minute groups, it's obvious the gun likes the bullet and the chamber likes the seating depth you've selected. Any progress from this point will have to be in the area of reducing ballistic variation down to single digits. There will be a "sweet spot" for loading density, but you can't find it without a chronograph.