Virgin Brass VS Fireformed brass

[Harveyn]

I just picked up 200 Virgin Palma 308 brass and would like to know how much of a difference there is from virgin brass to fire formed. I previously used Winchester once fired from factory loads in my rifle, so when i did load development on that batch of brass, it was already shaped to my chamber. I'd like to develop my load on fire formed brass anyway because i plan to neck size only, but is there any useful data that i can gain from the fire forming process? Seems like a waste of time and money just blasting 200 rounds just to fire form. What kind of accuracy, pressure, velocity and load differences will you see with virgin vs fire formed brass?

Thanks

 

[ncd89]

I found that using fire-formed brass made a large positive difference on my LD results.

First, case capacity changed by a lot (probably by more than a grain of powder using Varget in a .308 case) even with running the case through a body die after the first firing. I would think your case capacity would increase even more given that you plan on only neck sizing.

Second, and I think most important, neck tension was noticeably different. I could feel the difference while seating bullets and it showed in my SD and ES numbers once I fired the rounds. The neck tension on my virgin Lapua brass was very tight. With the previously fired brass, once the necks were blown out and then resized with a Lee collet die, there was a great deal more consistency in seating feel and velocity. I didn't do a controlled and careful test of virgin brass vs once-fired brass, but I'm talking about a difference in 5-shot group SDs of about 12 fps with the virgin brass vs. 5 fps on the once-fired brass. Could be a coincidence, as a 5-shot group isn't much of a sample, but given how obviously different the neck tension was while seating bullets, it seems to matter to me.

I don't like the idea of wasting money fire-forming, but, for me personally, I don't plan on ever doing LD on virgin brass again.

With a recent batch of virgin brass, I fire-formed with cheap bullets and about a 2/3 powder charge. I also won't be doing that again either, as when I ran the cases, which were mixed in with some previously-fired full-powered powder charge loads, through the body die, I could easily tell which cases had been fired with the reduced loads. I have to believe that case capacity in the lower-power loads has not increased as much as in the full-power loads.

In sum, I'm going to fire form all virgin brass with full-powered loads going forward before doing LD or using the rounds for any precision shooting.

Hope this helps.

 

[ncd89]

I found that using fire-formed brass made a large positive difference on my LD results.

First, case capacity changed by a lot (probably by more than a grain of powder using Varget in a .308 case) even with running the case through a body die after the first firing. I would think your case capacity would increase even more given that you plan on only neck sizing.

Second, and I think most important, neck tension was noticeably different. I could feel the difference while seating bullets and it showed in my SD and ES numbers once I fired the rounds. The neck tension on my virgin Lapua brass was very tight. With the previously fired brass, once the necks were blown out and then resized with a Lee collet die, there was a great deal more consistency in seating feel and velocity. I didn't do a controlled and careful test of virgin brass vs once-fired brass, but I'm talking about a difference in 5-shot group SDs of about 12 fps with the virgin brass vs. 5 fps on the once-fired brass. Could be a coincidence, as a 5-shot group isn't much of a sample, but given how obviously different the neck tension was while seating bullets, it seems to matter to me.

I don't like the idea of wasting money fire-forming, but, for me personally, I don't plan on ever doing LD on virgin brass again.

With a recent batch of virgin brass, I fire-formed with cheap bullets and about a 2/3 powder charge. I also won't be doing that again either, as when I ran the cases, which were mixed in with some previously-fired full-powered powder charge loads, through the body die, I could easily tell which cases had been fired with the reduced loads. I have to believe that case capacity in the lower-power loads has not increased as much as in the full-power loads.

In sum, I'm going to fire form all virgin brass with full-powered loads going forward before doing LD or using the rounds for any precision shooting.

Hope this helps.

I should also add that the once-fired cases were annealed after the first firing, which could also help with the consistency I experienced, although I'm aware that all Lapua cases are annealed at the factory.

 

[GhengisAhn175]

You can start load development with virgin cases. You should
be able to find your node. Just fine tune after firing cases

 

[Harveyn]

Thanks a lot. That is really useful information. I didn't like the idea of wasting money fire forming but i guess nothing in the precision rifle game is cheap. I'll just use the fire forming process to figure out a better starting charge rather than using the starting charge from a loading manual. Should enable me to start slightly higher. I'll probably use some 168 ZMax bulk i got left over for fire forming and then ill develop with ADI AR2208 (Varget) and 155 berger hybrids. I'll keep this thread updated with my findings from this experience to help other forum members.

 

[Sig Marine]

I agree agree with GhengisAhn. As for neck tension, you can size your brass using your expander ball without bumping the shoulder or use a mandrel to make your necks more uniform. I've used virgin brass (Lapua) for load work on several rifles using Dan Newberry's OCW method and found that if I have identified my optimum charge weight correctly, there is very little difference when using fire-formed brass.

 

[gigamortis]

I haven't found much difference in performance between virgin and once fired in my Savage chambers. As far as virgin Lapua brass prep goes, all I do is neck size it with the Lee Collet die and load it. Neck tension with virgin Lapua brass is definitely tighter than my Lee Collet sized once fired brass. Depending on the lot of virgin Lapua brass, its sometimes a slight interference fit with my Collet die mandrel fresh out of the box on initial neck sizing/forming. On my once fired, I run about .0015" to .002" neck tension with annealed necks and shoulders.

 

[Supersubes]

I dont think there's a practical difference. I full length size always, so my brass will always be smaller than the chamber. Brass "fitting the chamber perfectly" which creates better accuracy is a myth. Only real difference after that is the virgin brass is a bit rounded at the corners and radiuses, and after firing tend to be a little sharper. As far as virgin necks go, make them correct before the first firing using your die or a mandrel. I use a mandrel.

 

[orkan]

I always get more flyers with virgin brass. Always.

Most people have a tendency to start load dev at the wrong time. New barrels with less than 100-150rnds on them can be quite finicky. They'll often pick up a 100fps on their way to coming in. So I always recommend folks load up something mild and get a firing on their first hundred pieces of brass. Still plenty to be learned with those first rounds... but don't be so afraid to shoot.

You can do all the weighing and sorting you want, but until you shoot it and see where it prints... you aren't going to have a clue if that piece of brass is junk. It takes 2 firings minimum to accomplish that kind of sort. You can't trust the virgin firing, but if that case throws it out on the second also, you can be pretty sure to toss it aside to be used exclusively for testing/foulers.

Once you've done enough, you will usually have a workable load figured out within 30rnds or less, and can fine tune if you feel like going through the trouble. Truly no substitute for experience when it comes to load development.

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