Annealing magnum cases

[Ishallbie O'Cullkillin]

I've been using the darkroom method, exposing the case neck to propane flame for 4-5 seconds to just achieve a dull red glow, then tipping the drill to drop the case in water. It goes quick, and have done thousands of .223 & .308 this way. I finally got around to my .300wm brass, using the same method, but skipped the water drop, & instead just threw them on a cardboard pizza box. These cases cracked just above the belt under moderate loads. I had to recycle 200+ pieces of once fired .300wm Winchester brass. Now I am about to resize 100pcs of twice fired Lapua .338LM brass, and want to anneal, but have lost confidence in the process. I think the water quench is essential, but keep reading that it's not necessary. Does heavy/thick brass require a different technique than the light/medium calibers? Should I continue water quenching?

 

[MtnCreek]

Re: Annealing magnum cases

Water stops the heat from migrating, but those 300wm cases must have been ready for head seperation anyway. I assume they've been fl sized many times, correct?

 

[Ishallbie O'Cullkillin]

Re: Annealing magnum cases

Negative, Homes. Once fired.

 

[ksthomas]

Re: Annealing magnum cases

You've got a headspace problem, which is pretty common for belted magnums. It has nothing to do with the annealing, one way or the other.

Belted cases need to be reloaded just like conventional rimless bottlenecked cases; ignore the belt entirely. Headspacing it off the belt virually guarantees short case life, and split cases within just a very few firings. Don't push the shoulders back anymore than absolutely necessary and disregard the belt completely. L.E. Wilson makes an adjustable gage to allow for setting up your dies accurately, and will go a long way towards getting maximum case life. Adjusted this way, belted cases should last nearly as long as conventional rimless designs.

 

[former naval person]

Re: Annealing magnum cases

Headspace. Short cartridge to begin with. Annealing shouldn't go down that far anyway.

 

[Ishallbie O'Cullkillin]

Re: Annealing magnum cases

I only suspected the annealing because the virgin Winchester brass shot fine. I have been using the RCBS instructions, kiss the shellholder, then 1/4 turn in & set lock ring. The annealed brass was fired in a different rifle, one time, then annealed,FL sized, & fired again in the current rifle. The virgin brass that was fired in the current rifle need only be neck sized & trim if necessary, correct? Headspace gauge ordered.

 

[ksthomas]

Re: Annealing magnum cases

Sounds like it was that first firing that did the damage, and that's the curse of the belted magnum. Yes, you're following ther die instructions to the letter, and that's the other part of the problem. Without getting into a lengthy explanation, belts were originally added to cases to allow a surface for headspacing. Specifically, cases like the 300 and 374 H&H Magnums; cases with long, sloping shoulders that manufacturing equipment of the day couldn't hold uniformly enough to assure proper headspacing. The belt was added, since it allowed the case to feed through a bolt action magazine, but still offered a good surface to headspace from. The newer magnums, those with straighter walls and modern, sharper shoulders can easily headspace off the shoulders, making the belt nothing more than a sales gimmick. Problems come in when the shooter still tries to use the belt for headspacing, which allows that shoulder to be pushed back too far, and blow out again upon the next firing. The result is short case life and head separations, just like what you've seen. Go with the gage, and adjust the dies to where you're just barely bumping the shoulders back, like any conventional rimless case. That should get you going, and keep the damage caused by that first firing from getting too much worse, too quickly.

Hope that helps.

 

[turbo54]

Re: Annealing magnum cases

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MattK287</div><div class="ubbcode-body">I have been using the RCBS instructions, <span style="font-weight: bold">kiss the shellholder, then 1/4 turn in & set lock ring.</span> The annealed brass was fired in a different rifle, one time, then annealed,FL sized, & fired again in the current rifle. The virgin brass that was fired in the current rifle need only be neck sized & trim if necessary, correct? Headspace gauge ordered. </div></div>

That is reloading 101.

<span style="font-weight: bold">IMMEDIATELY</span> after learning reloading 101, a reloader should learn reloading 201, which is to size cases for proper headspace.

You need cartridge headspace measuring tools, and to use them. That will solve your problem.

Your darkroom/dull red annealing procedure is good - keep doing it, though the water "quench" is indeed, unnecessary.

 

[Bigwheels]

Re: Annealing magnum cases

I have anealed hundreds of win 300wm cases using exactly the same process you did, & have hundreds with 8 firings on them without a single issue. Of course there are a few that have loose primer pockets but I have never split a case or had one separate.

 

[Squid284]

Re: Annealing magnum cases

Some thoughts to ponder, or not:

Get headspace measuring tools (caliper, comparator body, inserts, sinclair makes good ones) and measure your fired cases. They should all be about the same. Adjust your sizing die so that it bumps the shoulder back .001". Spacers or redding comp shellholders will still give positive contact between die body and the shellholder, it's more consistant that way.

As your belted cases go through several firings, you should check to see how thin the case walls are getting just above the belt. With a light you can see a ring form inside the case where there is less material. RCBS case master will also give you an idea of how thin the band is getting. A pale white ring on the outside about a quarter inch above the belt tells you that you should have tossed it last time and that head separation is imminent.

If this is happening after one reload however, it's probably best to check your rifle's headspace. Belted mag cases should last 8-10 reloads or more if your sizing the brass/shoulder minimally. Given that, do you need to anneal your cases after every firing (or the first one)? That sounds a little excessive. Does this still happen without any annealing?

 

[Ishallbie O'Cullkillin]

Re: Annealing magnum cases

The cracking only occurred with the once fired annealed brass, and not the virgin brass I was annealing to get more uniform neck tension. The cracks are so small, I may have not noticed them, had these cases not stuck in the chamber. I checked headspace today, and it is excessive. This is a 30" AMU/MTU 5R Rock stainless fluted on a bluprinted Rem700 action, in a McMillan A3. I'm driving the rifle down to Medford next week so the smith can rectify the situation. I recycled 200 bucks worth of good brass, and need someone to hold me now. Thanks everyone for helping me solve this issue, I hope I can return the favor to someone.