Virgin brass vs. once fired.

[AZ82New]

Hello,

I worked up a load with virgin 280 AI Petersen brass. It shot great, roughly 1/2 MOA with an ES of 6fps.

I wet tumbled the bras, annealed it, Re-sized and the exactly copied the original load…sme lot of primers, powder, bullets etc. seating depth the same.

It e fed up shooting over MOA, the velocity was 30 fps faster and the ES was in the 20's.

Oh, I also used the same expander mandrel.

What gives?

I figured I messed up annealing it.

Conversely, I worked up a load with once fired 300 WSM brass…..all the same prep…..it shoots great. All touching.

I throw the same powder charge, primer, powder etc….and I ran it through a the same die to make sure the neck tension was the same as the once fired.

It shot terribly.

Anyone else have the same experience?

 

[GLTaylor]

You almost never get consistant results until after you've fire formed your brass in your chamber. Start your load workup with at least once fired brass.

 

[FEENIX]

Hello,

I worked up a load with virgin 280 AI Petersen brass. It shot great, roughly 1/2 MOA with an ES of 6fps.

I wet tumbled the bras, annealed it, Re-sized and the exactly copied the original load…sme lot of primers, powder, bullets etc. seating depth the same.

It e fed up shooting over MOA, the velocity was 30 fps faster and the ES was in the 20's.

Oh, I also used the same expander mandrel.

What gives?

I figured I messed up annealing it.

Conversely, I worked up a load with once fired 300 WSM brass…..all the same prep…..it shoots great. All touching.

I throw the same powder charge, primer, powder etc….and I ran it through a the same die to make sure the neck tension was the same as the once fired.

It shot terribly.

Anyone else have the same experience?

I cannot speak for everybody, but I do not do load development with virgin brass. My load development start after all the brass is fired off the rifle's chamber. In your case, you need to make the necessary adjustments to reduce your desired ES/SD. Good luck!

 

[can1010]

pretty common, back your charge down 1.5gr and work up in 0.3gr increments until your accuracy returns. usually around between 0.7gr and 1.2gr lower depending how tight or loose your chamber is compared to the virgin brass.

 

[V35BTC]

Most virgin brass will expand by around at least 2% on the first firing, then you resize if. After re sizing, it will not be exactly the same as virgin. It will vary pressure, velocity, and barrel time a noticeable amount due to the larger case capacity. Some times it matters, some times it doesn't. YMMV

 

[Rick Richard]

What everyone else has said.

 

[Mark37082]

I too have run into this issue. If you buy 250 new brass when you get a new rifle, that is a lot of shooting to get fire formed brass. It is hard for me to not start collecting load data on new brass. There are the issues of component expense as well as availability. Patience has never been my strongest attribute.

 

[sable tireur]

I too have run into this issue. If you buy 250 new brass when you get a new rifle, that is a lot of shooting to get fire formed brass. It is hard for me to not start collecting load data on new brass. There are the issues of component expense as well as availability. Patience has never been my strongest attribute.

This is probably more true for most of us shooters, we want to get on with the shooting and not the fireforming. Understood.

This doesn't help necessarily but, when we order custom dies the maker usually wants brass which has been fired at least 3 times. This will insure that the brass has been sufficiently formed to your chamber for consistency.

Currently with the excessively over priced components, the process of fireforming will be expensive. Add in the cost of the new barrel at the start and it's enough to give us pause to rethink what we want to accomplish. This is where the barrel break in can be a bonus as opposed to a handicap.

Consistency is what we're looking to accomplish, fireforming brass and the barrel break in are components of that. Unfortunately, some barrels can need upwards of 100 rounds to get the stability necessary for consistency while there are a few barrel makers which usually only require 20-30 shots to achieve consistency.

Enjoy the process!

 

[Window]

Hello,

I worked up a load with virgin 280 AI Petersen brass. It shot great, roughly 1/2 MOA with an ES of 6fps.

I wet tumbled the bras, annealed it, Re-sized and the exactly copied the original load…sme lot of primers, powder, bullets etc. seating depth the same.

It e fed up shooting over MOA, the velocity was 30 fps faster and the ES was in the 20's.

Oh, I also used the same expander mandrel.

What gives?

I figured I messed up annealing it.

Conversely, I worked up a load with once fired 300 WSM brass…..all the same prep…..it shoots great. All touching.

I throw the same powder charge, primer, powder etc….and I ran it through a the same die to make sure the neck tension was the same as the once fired.

It shot terribly.

Anyone else have the same experience?

For a hunting rifle, for me, less is more. Unlike most her, with a new barrel, it get 50 to 60 pieces of virgin brass. They all get fire formed and then load development starts. However, when fire forming, I do use a chronograph and will do OCW test to get a base line and where the velocity sweet spot is harmonically. Makes the starting point a little easier when starting load development with fire formed brass. This isn't the Bible by any means but it has served me well when trying to minimize the rounds down the tube when barrel life is around 1000 rounds.

 

[MtPockets]

You almost never get consistant results until after you've fire formed your brass in your chamber. Start your load workup with at least once fired brass.

Does that mean that fire forming is only fire forming, or is there useful information to be gleaned from that process?
I have a couple of ladders put together with vigin ADG brass and Hammers. Should I pull the bullets and use Hornadys for the first firing?

 

[Culpeper]

.5 moa with 6 ES is not adding up unless it was the rifle and or shooter.
Peterson is thick brass. It's AI deminsioned too. Anyway, your velocity should have decreased a little instead of increased a lot. What might you have done to the brass after the first firing that led to the material change downrange? You already answered that question.

The problem with the WSM sounds like a similar issue.

 

[Culpeper]

Does that mean that fire forming is only fire forming, or is there useful information to be gleaned from that process?
I have a couple of ladders put together with vigin ADG brass and Hammers. Should I pull the bullets and use Hornadys for the first firing?

No

 

[Mike Matteson]

Hello,

I worked up a load with virgin 280 AI Petersen brass. It shot great, roughly 1/2 MOA with an ES of 6fps.

I wet tumbled the bras, annealed it, Re-sized and the exactly copied the original load…sme lot of primers, powder, bullets etc. seating depth the same.

It e fed up shooting over MOA, the velocity was 30 fps faster and the ES was in the 20's.

Oh, I also used the same expander mandrel.

What gives?

I figured I messed up annealing it.

Conversely, I worked up a load with once fired 300 WSM brass…..all the same prep…..it shoots great. All touching.

I throw the same powder charge, primer, powder etc….and I ran it through a the same die to make sure the neck tension was the same as the once fired.

It shot terribly.

Anyone else have the same experience?

Try and match your slower velocity and see how that works out. Fire-forming can take 2 to 3 times before it's done. It's normal to see a differents in velocity with fire-formed bass.
The other is measure up your new brass to what the fired brass is. You might want to check your brass length with unfired to fired brass too.

 

[Rosebud]

I'm a little different from others here! On ammo I'm only hunting with I do load development with whatever bullet I intend to use, using the Virgin brass. Then load up the remaining seventy five or eighty rounds and hunt with it for the next couple of years. When I'm down to about twenty or so then I neck shoulder bump, then reload knowing I'll have to drop the charge a touch and work up. Components are far to expensive to just shoot up hundreds of hammer bullets and primers to get second or third firings as some reccomend. When the Virgin brass will shoot great. I tell this the people I load for, when you have shot these up come back, we will work up another load for the once fired. Or maybe my pockets just aren't as deep as others. If it was PRC shooting I'd go a different route.