Annealing opening up groups?

[MikeMcCasland]

Mike I'll be shooting some loads I just finished last week that I too annealed the cases after numerous firings. It will be interesting to see if I too have a grouping issue.

Sounds good! Post up your results once you do. I'll circle back to this thread tomorrow to update on my testing.

 

[Bc'z]

Sounds like a plan

 

[Jeff A]

Annealing cases changes a factor affecting the harmonics associated with cartridge firing.<Snip>

Could you explain what you mean by this?

 

[MikeMcCasland]

At the range now; looks like seating depth is going to be the fix. It likes the original bushing though. Hates more neck tension. A single .001 bushing drop makes it a 5" group at 300.

 

[Bc'z]

Good news, I figure it out tomorrow got busy on wifes new stock.

 

[spclark]

Could you explain what you mean by this?

Sure.

Annealing case shoulders & necks alters the character of that part of the cases we use. Characteristics that have a bearing on release of resulting gas pressure once primer and propellant are ignited.

Timing of that release, as well as the space that opens thru which the gas - and bullet - are released, affect the rate and volume of gas released, as well
as the rate and magnitude of pressure waves passing into the rifle’s components.

Few folks have messed with generating pressure curves during load testing. The effect of annealed vs. un-annealed cases on pressure curves generated is quite readily apparent.

Mr. McCasland’s post about seating depth alteration 90 minutes ago illustrates how another variable can compensate for the differences he noted in his original post.

 

[divingin]

Mike;

A friend of mine has found similar results to what you did: Freshly annealed cases perform, well, at least differently, than those with a firing or two. He says it normalizes after putting an additional firing on the case.

I don't see that as I generally anneal every firing (and I'm not sure I shoot consistently enough to see that kind of change anyway.)

 

[Ledd Slinger]

I find it easier to tune a load on annealed cases because I can maintain the annealing. If I keep firing cases without annealing, the neck tension can change constantly as pieces are fired and become more and more work hardened. I cannot control work hardening, but I can control annealing cycles to keep the brass headspace and neck tension consistent.

That being said, if a custom chamber and FL die is carefully matched where only absolute minimal sizing takes place to allow smooth chambering on resized cases, the brass will work harden at a much slower rate and maintain elasticity for a lot more firings. In that case, the brass often will not require annealing to remain consistent.

 

[dkhunt14]

If I'm not mistaken your un annealed brass has more springback creating a lighter neck tension.
Might I suggest going up in bushing size by .001 and not down. As the annealed brass is more malleable and going down would create more neck tension.
Correct me if I'm wrong

This is not true. Bullet seating and bullet pull is much lighter with annealed brass. Matt

 

[Bc'z]

This is not true. Bullet seating and bullet pull is much lighter with annealed brass. Matt

Which is why he shouldn't use a smaller bushing on his annealed brass. Maybe on his un annealed to get good tension as it has more springback as it has been hardened.

I'm thinking you misinterpreted my post.
I've had to drop bushing size on un annealed brass to get bullet hold,
after poor boy annealing "drill n torch" I was able to go up in bushing size.

 

[Ledd Slinger]

This is not true. Bullet seating and bullet pull is much lighter with annealed brass. Matt

Agree to an extent. It actually can be true in some instances when using light neck tension.

I was just sizing a 6mm Rem cases yesterday. They had many firings on them and I could not get any resistance with my .240" expander ball as it pulled thru the neck on 2 cases. Brass was springing back too far from work hardening. Annealing helped get the neck tension back.

In instances where a work hardened case has the same neck ID as a freshly annealed case after sizing, then yes, the annealed case will exert less tension on the bullet.

 

[mgunderson]

Was a speed change observed?

 

[Webster]

If I'm not mistaken your un annealed brass has more springback creating a lighter neck tension.
Might I suggest going up in bushing size by .001 and not down. As the annealed brass is more malleable and going down would create more neck tension.
Correct me if I'm wrong

Unannealed would have more springback and more tenion not less. Annealed less tension.

 

[Richard Coody]

Unannealed would have more springback and more tenion not less. Annealed less tension.

Depends on whether you size with a bushing or full length sizing die with expander

Which way does the springback go?

 

[Toby Bradshaw]

@MikeMcCasland. ... If you follow this technique you will find that no matter what bushing size you use or gage pin/mandrel you use, the case springs back 0.005 each time.

Missing a zero.

 

[Bc'z]

Unannealed would have more springback and more tenion not less. Annealed less tension.

Yes un annealed has more springback as it is stiffer/harder, creating inconsistent tention.
Whereas annealed is softer more malleable giving a more consistent tension very noticeable while seating bullets.
I use bushing dies for all our bolt guns which is where I began to notice the problem in seating force or lack there of.
Small base dies for both 223/556 AR's, and 6x45 gas gun.
My high dollar anealer
Dont laugh it really does work!
Consistency in flame and time in flame.

 

[MikeMcCasland]

Was a speed change observed?

Yep, sped up from 2820, to 2870.

Ultimately dropping the powder charge slightly, and moving seating depth brought the groups back.

I've put a few hundred more rounds through the rifle, and have started annealing every firing; it's back to being consistent. ES/SDs were improved when I ran it over the chrony this weekend, but I also started using an FX120i, so unsure if that's attributable to the powder or annealing.

 

[moondog]

If you work up a load with annealed brass with same neck tension and anneal the brass every firing or enough to keep your neck tension the same I can’t see that being a problem, many shooters do it well..

Exactly that

 

[Webster]

Depends on whether you size with a bushing or full length sizing die with expander

Which way does the springback go?

Both cold work the the necks. Sizing down with a bushing or die and expander both cold work the brass. Up or down it's working the brass.

 

[Richard Coody]

Both cold work the the necks. Sizing down with a bushing or die and expander both cold work the brass. Up or down it's working the brass.

But if you size with a bushing spring back reduces neck tension.

If you size with a mandrel or expander ball spring back raises neck tension

As the brass work hardens this effect is more pronounced. Annealing every firing makes the spring back effect consistent instead of changing with every reloading cycle.