Sizing consistency after annealing

[parshal]

I've been looking online at some pictures and explanations. It seems to be most prevalent on cases that are necked up. Is it common to occur on cases that are just full-length sized to the same caliber? The existence of these donuts could explain inconsistent groups with previously proven accurate loads. Another part of my case inspection and a few more tools I guess. Upon further thought, this could cause a number of anomalies with previously perfectly performing loads.

You'll know when you've got a doughnut. When seating a bullet you'll feel it stop at the doughnut and it requires more effort to seat past it. I have to seat past the neck/shoulder due to long bullets and magazine restrictions. If you don't seat past that point you'll really not see any issue with a doughnut.

 

[JustMe2]

JustMe2,

I sincerely appreciate your concern.

The engineers who designed the AMP annealer, which I use, have shown in hardness testing that as long as you keep the annealing settings (time & heat) the same, repeat annealing does not change the brass hardness or grain structure of the brass.

Here is the video showing this:

The reason for annealing is to get an accurate, consistent hardness baseline for resizing with the same amount of work hardening occurring on every piece of brass when you re-size it.

The repeated working of the press is similar to holding the brass in the sizing die longer to get that last .0005" to .001" of sizing needed to bump the shoulder for smooth bolt operation. Brass hardening occurs when you deform it. The more you deform it past it's elastic limit, the more work hardening you induce.

I did NOT say annealing hardened the brass. Go back and read what I said. Multiple passes through your die is what you are doing wrong. Multiple passes through your die hardens your brass and is NOT the same as pausing for a few seconds.

 

[PddPdd]

I did NOT say annealing hardened the brass. Go back and read what I said. Multiple passes through your die is what you are doing wrong. Multiple passes through your die hardens your brass and is NOT the same as pausing for a few seconds.

I was not trying to imply that you said annealing hardens the brass.

So you believe running a piece of brass in and out of die (no die setting changes) hardens the brass further with each stroke?

 

[parshal]

Yes, that's what hardens brass. Work hardening by multiple manipulations of the brass size. An extreme example is bending a paperclip in the same place multiple times until it breaks.

 

[Tagnbagem]

Make sure you plenty of lube on case, differences in lube amounts can change how case acts in the die.

 

[Pudgy]

I've been having a similar issue with my 6.5 SAUM cases and ADG brass using Redding Competition neck bushing die. I have the ability to anneal with an Anne set up but instead of trying annealing as a first solution I switched to Short Action Customs modular die ($$). The die has essentially a bushing that resizes both the neck and shoulder bump together. Hopefully it will at a minimum get rid of the potential for internal doughnuts.

Part of my motivation for the switch was a recent article in Precision Rifle Blog that covered the reloading practices of one of the top shooters in detail. He annealed each time and used the SAC dies. I haven't gotten far enough with the SAC die use yet to confirm whether it will solve the issues I was having.

I use the SAC dies for 7 SAUM & 6.5 PRC followed by a mandrel. Some cases over 10 firings, I have never had an internal donut.
But if I'm over working the brass I can get an external buildup at the neck/shoulder area.
Hasn't effected shoulder bump or accuracy to date.

 

[vavaroutsos]

Cartridge Base To Shoulder is the dimension I am looking to get consistent sizing without too much hassle.

What press are you using? Is it possible the press isn't rigid enough and slight differences in force required to resize are causing some flex in the press?

 

[parshal]

Make sure you plenty of lube on case, differences in lube amounts can change how case acts in the die.

I've differing amounts of lube on cases size different. I'm pretty attentive to ensure that they have the same amount now.

 

[JustMe2]

I was not trying to imply that you said annealing hardens the brass.

So you believe running a piece of brass in and out of die (no die setting changes) hardens the brass further with each stroke?

Yes, that is correct.

 

[Ekupp]

There are quite a few videos on proper annealing on YT. Be very careful not to over do it. You don't want the brass to get to soft. Pay attention to how far down the heat streak goes. See videos on this. If you want, you could use Templac. When you size your brass, pause at the bottom of the press stroke (3-5 secs). This allows the brass to setup to your required size. Will reduce spring back. I shoot for 2-3 thousands. BTW, if you really want optimum control on your annealing, get an AMP. Pricy, yes. But they work.

Let me ask my question another way, for those of you using an AMP how much variance do you get in Cartridge base to shoulder when sizing after annealing? Assume: same brass lot, same chamber, same press, same die, same number of firings, same lube, dies cleaned periodically, same hold time in the press, etc.., all processed identically. Are you still getting stubborn pieces that dont size fully or some that overly size and size beyond the target dimension?

 

[C-130 Dude]

I was not trying to imply that you said annealing hardens the brass.

So you believe running a piece of brass in and out of die (no die setting changes) hardens the brass further with each stroke?

Every time you run your brass through the sizer die it will harden it.

 

[C-130 Dude]

Make sure you plenty of lube on case, differences in lube amounts can change how case acts in the die.

Watch over lubing. It will dent the upper area of the case.

 

[C-130 Dude]

Let me ask my question another way, for those of you using an AMP how much variance do you get in Cartridge base to shoulder when sizing after annealing? Assume: same brass lot, same chamber, same press, same die, same number of firings, same lube, dies cleaned periodically, same hold time in the press, etc.., all processed identically. Are you still getting stubborn pieces that dont size fully or some that overly size and size beyond the target dimension?

Can't help on this one. I've used a friend's, but dont have enough experience to say.

 

[Pudgy]

Let me ask my question another way, for those of you using an AMP how much variance do you get in Cartridge base to shoulder when sizing after annealing? Assume: same brass lot, same chamber, same press, same die, same number of firings, same lube, dies cleaned periodically, same hold time in the press, etc.., all processed identically. Are you still getting stubborn pieces that dont size fully or some that overly size and size beyond the target dimension?

I have amp annealed 3K plus rounds. (Mostly ADG brass) I used to get +/- .002 bump no matter what I did.
A .002 difference is the thickness of a piece of scotch tape, but it is significant.

I was using MEC press, SAC dies, AMP Annealing, same amounts of Imperial lube, this should not be happening! Drove me nuts. Then I figured it out. I was using hornady Lock n Load inserts. The inserts have a rubber o ring that was allowing almost imperceptible movement.

Remove the Lock n load inserts. Measured the next 100 pieces. They all were +/- .0005. Problem Solved