Home Forums Reloading Big Game Rifles A note about new vs. 1x fired brass

A few days ago I picked up a bag of new Federal American Eagle 7.62x51 NATO brass. As part of the first time prep I ran the necks over an expanding mandrel (Lyman M-die) to round them out and make the hole size uniform. I then assembled fifty of them into an approximation of Lake City M852 match ammunition.

Of the fifty there were fourteen cartridges showing .005" or more runout on the bullet ogives as measured with my old Sinclair test fixture. The numbers were written on the case bodies.

After firing they were deprimed and lightly neck sized with a Lee collet die. They were then FL sized using a Forster die with a custom honed neck and no expander in place, trimmed, and finally expanded with the M-die to match the first loading.

The following pairs of numbers indicate the first and second loading runout of the cartridges:

8,1
7,2
7,1.5
6,1
6,1
6,1
6,1
6,1
6,2
5,2
5,1
5,1
5,1
5,3

At this point I have not measured the case neck walls for uniform thickness. Experience tells me if I do take that measurement the one that only improved from .005" to .003" will not be the one with the best neck.

I've opined before that 1x fired brass is your best bet for tuning loads, and here's some evidence why. Some of you are thinking what's new here, but this note isn't really for the old hands.

I wouldn't call myself an old nor a new hand, but I find your post interesting. Thanks.

I've often "felt" the first firing and process of resizing, tidies things up. Your measurements solidify that feeling.

I enjoyed that read. Thanks for the post. Makes sense.

How did the accuracy follow along with the test? Did the accuracy get better or worse with your findings?

I haven't shot the second loading ones yet.

The bad runout stuff shot about moa for five shot groups, and that's pretty bad considering the test rifle is a Remington 40X equipped with a Leupold VX-3 6.5-20x40LR that I was using on 12x while aiming at a 1/2 moa dot. The .003" and less runout rounds (from the other thirty six of the first load batch) were half moa shooters.

How much difference would this make for a hunting rifle? I'm very new to reloading, so just trying to learn.

I haven't run this exact test in a hunting rifle, but I've done something similar with a hunting 308.

A friend came into a good bit of 7.62x51 Lake City match ammunition, both M118 and M852. I had sorted some by runout, labeled it in a way where I new what was what but my friend couldn't tell. He was the trigger man and did not know what he was testing, so he was shooting equally carefully for all the rounds. The bad runout stuff shot noticeably larger groups.

And yet forming AI brass is such a chore and waste of components.

Given the way a proper AI is chambered (headspacing new brass on the neck-shoulder radius) it may avoid first load issues too since the possibly out of round new case body is floating.

Shhh

So, why couldn't have the process after the first firing been done on the first loading? Even though "new" brass doesn't "need" it to function, it certainly improves consistency and uniformity if they are all run through the complete process, whether new or once fired. That's what I have always done, and never noticed a difference between new, once fired, and almost worn out brass.

New brass is often too small in diameter for a size die to touch up the case body.

In fact I did pre-process the other fifty by running them through the Forster die before their first loading. The results were better, but there were still several that loaded out at .005" and one at .006" runout. A few more at .004"-.0045" as well.

Good information mathman, I wouldn't have thought there would be that much difference between first and second firing.

I have a question regarding your second firing prep.
Why neck size (squeeze the neck down), then body size, then open the neck back up?
Doesn't the Lee collet die leave the proper neck tension?
I haven't used the Redding M dies so I'm just trying to understand your procedure.

MM,

Thanks for sharing your data. I can't say it surprises me, but there's no substitute for a controlled test.

I wanted to use the Forster full length sizer w/o an expander ball since I prefer to expand in a subsequent step. This means one way or the other I needed to deprime the brass, so I used the Lee collet sizer to deprime and the neck sizing it did made the pass through the Forster die that much easier. The Forster die neck has been honed so that thicker brass like LC, FC or Lapua is not sized down too much in the neck. The expander mandrel in the Lyman M-die doesn't have to open the full length of the necks very much, I mainly used it to get the step expansion of the end of the case mouth.

I was fiddling around testing a couple of ideas that didn't bear directly on the first vs. second prep runout comparison.

The Lee collet die does size the necks the way I want them, and I use it solo quite often.

Here's a list of changes for a different set of the LC15 brass. These had been run through the Forster die w/o ball before their first loading. I just finished up their second loading whose processing included Lee collet neck sizing and Redding body sizing.

6 --> .5
5 --> 2
5 --> 1.5
5 --> 1
5 --> .5
5 --> 0
4.5 --> 2
4 --> 2.5
4 --> 1.5
4 --> 1.5
4 --> 0
3.5 --> 1.5
3 --> 1.5

mathman, thanks for the response.
I've got a new Kriegar .223 barrel arriving tomorrow and some new Lapua brass to load for it. I've been trying to refine my load procedures for max accuracy. May have to give the Lyman M die a try.

I much prefer 1x over new to start load dev for new loads and find it to be just as accurate as 1x or 2x from the same rifle. It's nice to be able to get to .002 HS before the first firing while doing load dev in a new chamber. That said, I've certainly shot some nice groups FFing with straightened virgin rounds that had a hefty HS.

The M-die is neat but it isn't a must have, especially if you're using a "competition" type die that holds the bullet in alignment with the case neck before the actual seating begins.

Where I've found it particularly nice is increasing the ease of starting bullets straight into the case when a conventional seating die is being used. For example, using the M-die as an add on I'm able to consistently load really straight cartridges using a vanilla RCBS two die set for an accurate 300 Savage I have. The two die set is actually pretty good by itself, but for a long while now I've found the use of the M-die worth the extra step.

By failing to properly prep the new brass you made an unfair comparison.