Virgin brass and load development

[BossGobbler2024]

Curious as to what others do"

When starting with virgin brass and already have a load developed for a rifle
Do you size the brass to your dimensions and continue on per usual or fire form and size before considering them good to go?
Or just load and fire away?

vs
starting with virgin brass and not having a load developed yet.
Do you fire form each piece with a moderate load or just starting working your charge ladder with the virgin brass?

 

[Tanner]

As long as your load isn’t on the ragged edge of too hot, and you’re using the same brand of brass… I just load ‘em the same and send it.

Switching brands of brass it seems prudent to at least start a grain- 1.5 under your previous load and confirm safety…

 

[wapitibob]

I shoot all my virgin brass in a shot out barrel and a slightly reduced load. My brass has .020" growth at the shoulder datum between virgin and twice fired. First fire moves it about .016" which is close enough to finished size that they shoot fine.

 

[260shooter]

If you don't have a fireform barrel. I would run it over a expander mandrel then through a FL bushing die to get desired neck tension. Do a small ladder test to find velocity and as long as you're not seeing pressure signs, load and shoot.

 

[HuntHarder]

Using Lapua brass, I have not seen any noticeable difference from once fired to new. I also do not load my rounds to the pressure max. On new brass, I usually just run a mandrel thru real quick to make sure the neck's are round. Prime, load and shoot.

 

[Jason Snyder]

I don’t check for pressure with virgin brass. Use once fired or you may end up with some excessively hot loads.

 

[eoperator]

I shoot all my virgin brass in a shot out barrel and a slightly reduced load. My brass has .020" growth at the shoulder datum between virgin and twice fired. First fire moves it about .016" which is close enough to finished size that they shoot fine.

Oh my, you need a shot out barrel to fire form brass that grows .02"? There are modern cartridges that would eliminate the need for this readily available.


I run a mandrel through new brass and go on with life. If your old load was on the "ragged edge" you may end up with problems if you go to brass with less capacity.

 

[Harvey_NW]

I just finished testing a similar comparison in my rifle, and even though the dimensions seemed like there wasn't going to be a significant difference, there was. If I was introducing new brass to a proven load, I would probably load from 2gr below up to 1gr above in .5gr increments (pressure ladder) and fire those making sure there's no pressure signs, then load 10 and verify.

New brass ran over expander mandrel painless load dev -
88° 59gr had no pressure signs and was 3,007 fps. I settled on 58gr at 2930fps avg for the load.
36° the load avg 2893fps, so pretty awesome temp stability.

1x fired brass, FL sized .002-3" shoulder bump -
38° 58gr avg 2947fps and had noticeable bolt lift. I dropped the charge 1.5gr.
29° 56.5gr avg 2857fps


Going forth I'll probably stay more on the mild side first firing, and then stiffen up the charge after they're formed. But with this load I didn't feel like wasting the components just to form brass, as the initial load shot plenty good.

 

[Wyobohunter]

Curious as to what others do"

When starting with virgin brass and already have a load developed for a rifle
Do you size the brass to your dimensions and continue on per usual or fire form and size before considering them good to go?
Or just load and fire away?

vs
starting with virgin brass and not having a load developed yet.
Do you fire form each piece with a moderate load or just starting working your charge ladder with the virgin brass?

First thing I do is FL size and fire form with a lite load, then neck size after that.

 

[BossGobbler2024]

I just finished testing a similar comparison in my rifle, and even though the dimensions seemed like there wasn't going to be a significant difference, there was. If I was introducing new brass to a proven load, I would probably load from 2gr below up to 1gr above in .5gr increments (pressure ladder) and fire those making sure there's no pressure signs, then load 10 and verify.

New brass ran over expander mandrel painless load dev -
88° 59gr had no pressure signs and was 3,007 fps. I settled on 58gr at 2930fps avg for the load.
36° the load avg 2893fps, so pretty awesome temp stability.

1x fired brass, FL sized .002-3" shoulder bump -
38° 58gr avg 2947fps and had noticeable bolt lift. I dropped the charge 1.5gr.
29° 56.5gr avg 2857fps
View attachment 815621

Going forth I'll probably stay more on the mild side first firing, and then stiffen up the charge after they're formed. But with this load I didn't feel like wasting the components just to form brass, as the initial load shot plenty good.

That is good information. I assume you were using the same brand of brass? What was the difference in? Point of impact, group size, velocity, all of them?

 

[BossGobbler2024]

First thing I do is FL size and fire form with a lite load, then neck size after that.

Have you ever FL size then put your developed load into virgin brass of the same type you were using?

 

[Wyobohunter]

Have you ever FL size then put your developed load into virgin brass of the same type you were using?

I do that for cases I FL size, like semi auto. I’d do the same for any case I planned to FL size as part of reloading that cartridge. I don’t work up a new load for new brass, I don’t do it for any other new components either (new lot of the same powder… etc). If I were really pushing the envelope of max, I might. I never go to max load though. I prefer to have a safety margin, an extra 20-50 fps is beyond the point of diminishing returns.

 

[wyosam]

Assuming same brand of brass? Nope. Load and go. I even have ackley barrels that my normal load will fit in new parent case brass- shoots just fine. ES is a little wider, but roughly centered on the same velocity. Those are chambered correctly so parent case brass is a tight fit. Chamber size (minus the space actually taken up by brass, not airspace around it) is the primary determinant of pressure/velocity. Unless you’re compressing powder and changing the burn characteristics physically, swelling the brass to fit the chamber with a full load takes very little energy.


Sent from my iPhone using Tapatalk

 

[TaperPin]

Fire forming uses a little bit of energy to stretch the brass into all the corners, so that energy isn’t available to push the bullet and velocities will be slower by a tiny amount. It’s so little I rarely pay attention to the difference. I’d gladly hunt with new brass or fired brass as long as the two aren’t mixed.

 

[wind gypsy]

Oh my, you need a shot out barrel to fire form brass that grows .02"? There are modern cartridges that would eliminate the need for this readily available.

Pretty sure he shoots 7 STW. Thus i could understand if a guy had 100+ new pieces he wanted to fire form without digging into the already short barrel life to get the shoulders fitted to the chamber. Slightly different consideration compared to non-belted cartridge that actually headspaces off the shoulder to start. Not sure how much difference it makes but i have jammed the lands for first firing in 300WM to help get things formed well myself.

 

[wapitibob]

Pretty sure he shoots 7 STW. Thus i could understand if a guy had 100+ new pieces he wanted to fire form without digging into the already short barrel life to get the shoulders fitted to the chamber. Slightly different consideration compared to non-belted cartridge that actually headspaces off the shoulder to start. Not sure how much difference it makes but i have jammed the lands for first firing in 300WM to help get things formed well myself.

Yes, 7stw n570 and berger 195's. I want every thing the same, including case capacity so I form virgin brass.
350 shots and throat burned back .100". I have an excess of powder and bullets I will never use, so expanding the case with these components, in an old barrel, was a non issue. Chamber shoulder datums are within .002" between barrels.
With the burned up throat I'm now able to seat the 195's .020" off the lands and have the boat tail above the neck/shoulder jct. After moving the bullet out, it now shoots little groups, better than it's ever shot in it's life, but I'm on borrowed time using the N570.
I could buy a custom reamer with the shoulder pulled back so the brass wouldn't grow, and freebore for the 195's but will probably chamber the next barrel in 7 prc. Brass is better and easier to find, and I can get the 195's where they need to be from the start.

 

[HuntHarder]

I just finished testing a similar comparison in my rifle, and even though the dimensions seemed like there wasn't going to be a significant difference, there was. If I was introducing new brass to a proven load, I would probably load from 2gr below up to 1gr above in .5gr increments (pressure ladder) and fire those making sure there's no pressure signs, then load 10 and verify.

New brass ran over expander mandrel painless load dev -
88° 59gr had no pressure signs and was 3,007 fps. I settled on 58gr at 2930fps avg for the load.
36° the load avg 2893fps, so pretty awesome temp stability.

1x fired brass, FL sized .002-3" shoulder bump -
38° 58gr avg 2947fps and had noticeable bolt lift. I dropped the charge 1.5gr.
29° 56.5gr avg 2857fps
View attachment 815621

Going forth I'll probably stay more on the mild side first firing, and then stiffen up the charge after they're formed. But with this load I didn't feel like wasting the components just to form brass, as the initial load shot plenty good.

Interesting. Which brand of brass was this? I literally just did the exact same thing and noticed nothing of significance. Mine was 6.5 cm lapua brass with 42.5 gr of H4350.

 

[Harvey_NW]

That is good information. I assume you were using the same brand of brass? What was the difference in? Point of impact, group size, velocity, all of them?

Yes, started with a new lot (100pcs) ADG brass after having my chamber touched up with the AW2 reamer.

New brass initial load proof 10 shots @ 88° - 58gr, avg 2933, ES 62fps, SD 24fps.


New brass cold test @ 36° with last 7 loaded (I adjusted a click right prior to season based on a small sample size and shouldn't have) - 58gr, avg 2893, ES 65fps, SD 22fps.


1x fired brass test 10 shots @ 38° (1 click left to correct zero) - 58gr, avg 2947, ES 39fps, SD 13fps.


1x fired brass test 10 shots @ 29° - 56.5gr, avg 2857, ES 57fps, SD 16fps.


Group size was within the expected variability based on previous groups, but did shrink back to the same size as the original proof group when I did initial development. POI group center shifted ~1/2" right with the drop in powder. I adjusted 2 clicks left, shot a 3 shot group to confirm, and then validated out to 1,012 yards the following day.

Interesting. Which brand of brass was this? I literally just did the exact same thing and noticed nothing of significance. Mine was 6.5 cm lapua brass with 42.5 gr of H4350.

See above. It was a pretty stiff charge to start with so that was the point of testing this, along with gathering cold weather velocities for temp sensitivity inputs in my solver.

 

[wind gypsy]

Yes, started with a new lot (100pcs) ADG brass after having my chamber touched up with the AW2 reamer.

New brass initial load proof 10 shots @ 88° - 58gr, avg 2933, ES 62fps, SD 24fps.
View attachment 815747

New brass cold test @ 36° with last 7 loaded (I adjusted a click right prior to season based on a small sample size and shouldn't have) - 58gr, avg 2893, ES 65fps, SD 22fps.
View attachment 815748

1x fired brass test 10 shots @ 38° (1 click left to correct zero) - 58gr, avg 2947, ES 39fps, SD 13fps.
View attachment 815750

1x fired brass test 10 shots @ 29° - 56.5gr, avg 2857, ES 57fps, SD 16fps.
View attachment 815751

Group size was within the expected variability based on previous groups, but did shrink back to the same size as the original proof group when I did initial development. POI group center shifted ~1/2" right with the drop in powder. I adjusted 2 clicks left, shot a 3 shot group to confirm, and then validated out to 1,012 yards the following day.


See above. It was a pretty stiff charge to start with so that was the point of testing this, along with gathering cold weather velocities for temp sensitivity inputs in my solver.

Did first to second firing coincide with a possible barrel speed up at all? I've seen similar results but most times it happens in concert with barrel speed up as new brass often means new barrel.

 

[Harvey_NW]

Did first to second firing coincide with a possible barrel speed up at all? I've seen similar results but most times it happens in concert with barrel speed up as new brass often means new barrel.

Don't think so, barrel had 180 rounds on it when it was touched up and throated out so the only "break in" would be the new throat, which I figure would have been fouled and stabilized in the 100 firings of new brass. Barrel hasn't been cleaned since new.