Annealing and fire forming cases??

[LDBennett]

My son-in-law and I have decided to get into a 50 cal rifle. Since we live in California 50BMG is outlawed. But the devious Californians found a way: convert 50BMG to 50DTC. It is legal because the law prohibits 50BMG not all 50 cal guns.! It's the same 50BMG case with the shoulder reshaped and ever so slightly shorter. It uses 50BMG bullets and primers. BOHICA can supply the bolt operated upper to fit our AR-15 lower we just put together . Commercial ammo, of course, is un-obtainable (???). So the cases must be fire formed to the new chamber. It has been suggest that the case shoulders be annealed before sizing in a 50DTC sizing die and fire forming the brass in the gun.

Here is my planned approach and if anyone see something wrong please speak up. Ruining the brass at a buck a case is not cost effective:

1) Deprime all the cases with a punch (carefully). I'll make a base on the lathe to hold the case with a hole to allow the primer to fall out.

2) Mark the case shoulder with a 700 degree temperature crayon all the way around.

3) Set a pan of water on a home made turn table

4) Set the case in the pan of water vertically so that more than half of the body of the case is in the water and the case shoulder is out of the water.

5) Using a propane torch on the case shoulder while rotating the turn table, heat the shoulder until the crayon indicates 700 degrees F is reached.

6) Immediately tip the case over into the water to completely submerge it to cool it.

Anyone see a problem with doing it this way?

How much of a download should be used to fire form the case in the gun, if at all? 50BMG case wall thickness is 0.024 inches on the Once Fired brass I just bought.

Will a propane torch do it or will I have to use my acetylene torch? I am only going to do 50 cases.

And yes, I'll remove the primer crimp.

LDBennett

[jdon72]

LD,

Talk to Gearheadpro or pyro. He is working on an annealing device. He also has videos on youtube and it is being professionally done. It impressed me. Just search his threads...there was one a few weeks ago. GL

J

[LDBennett]

jdon72:

I know about the device but I only have 50 case to do. His device would be good if I did this all the time. In 25 years of reloading I have never had to anneal case before and I suspect after doing these 50 case I'll probably never have to do it again (??). But thanks for trying to be helpful.

LDBennett

[jdon72]

No prob

[The_Rifleman]

I would just use the lowest charge recommended for that cartridge.

I use a propane torch set fairly low. I put my case in a deep-well socket on a 10 inch extension and hold the case so the blue point of the flame touches the area I am annealing. I then turn the socket apparatus until I see the flames turn orange, I then make sure I rotate it a whole turn then dump the case into water.

Many will wait until the case glows orange but I don't heat mine as much.

[JLA]

I anneal tha same way rifleman does it except I chuck my cases in a drill via the LEE trimmer stud and turn them fairly quickly while heating. this gives me an even heat, and i dont bother quenching. I believe it makes the brass brittle.

Getting the .50 BMG chucked in a drill may be a daunting task. I dont know if LEE offers a trimmer for it...

[jdon72]

LD,

I just remembered that gearhead will do the annealing for you...I do not know how much he charges, but he may do yours for a promotional deal. However, it takes the fun and pride out of one owns work.

GL

J

[LDBennett]

JLA:

My understanding and experience is that is copper [and brass is supposedly 30% zinc and 70% copper (??)] becomes softer (anneals) with heating and quenching. Quenching will not make it more brittle but will freeze the crystalline structure in the soft state. Slow cooling will allow the brass to return to a harder state than annealing with quenching. Maybe slow cooling removes most of the work hardening but annealing with a cold water quench will make the cases softer. That is my understanding and what I have observed over the years when annealing copper gaskets for motorcycles.

jdon72:

If what I proposed is all the work I need to do to anneal cases then I WANT to do it my self for the very reasons you suggested. If the process is much more complicated then I might choose to have others do it for me.

But thank you for the thought that the "guy" may do it for others. I did not know that. I thought he was just going to sell the machine when he got it done(???).

LDBennett

[Gearheadpyro]

LD:

Your process is pretty right on, except you don't need to quench brass. Quenching steel will affect the crystal structure. Quenching brass does nothing but get the case wet.

750F or so is about as hot as you can get it without making it too soft, 700F is a good target.

Try to turn the case fast enough to keep the heating even, the big key to annealing is consistency. If you have access to a power screwdriver try chucking a socket that closely fits the case and using that to turn it.

Once I have my machine (I.C.A. 2000) built I will anneal other's brass if they would like, but it is not running yet. I do also plan to sell the machine, however, it will not be able to handle the big 50's. Due to the nature of the induction heater I will use the work coil will need to be close to the case. If I build the machine to work for the big 50's it will have difficulties with the far more popular .223's.

[howlnmad]

Originally Posted by JLA

I anneal tha same way rifleman does it except I chuck my cases in a drill via the LEE trimmer stud and turn them

Getting the .50 BMG chucked in a drill may be a daunting task. I dont know if LEE offers a trimmer for it...

Yep, they do. Midway has one listed for 14.99.

[JLA]

Thanks LD, I did look into that since posting here last. Next go round with annealing ill quench and see how it goes.

[LDBennett]

JLA:

In an old article from the 1950's the writer points out that you can not allow the base of the cartridge to get any heat at all or it will be so soft that it will loose its required strength. That is why you stand them in water. If you allow them to air cool as suggested by some, the heat from the shoulder will eventually get transfered to the base and MAYBE effect it (??). Quick cooling by tipping the heated case over into the water assures that the shoulder heat never gets to the case's base.

LDBennett

[Gearheadpyro]

LD,

Brass changes its crystalline structure (softens) at around 450F, if you apply enough heat quickly enough to the neck area you will never get the base up to that temperature. Annealing a case should only take a few seconds regardless of the method used.

There is nothing wrong with standing the cases in water to prevent heat transfer, it's just not essential.

[JLA]

I think ill just keep doing it the way i do it. I can touch the base after annealing, thats how i get it out of the trimmer stud. then I stand them up in a plastic loading block and it doesnt melt. Thatll save me from having to wait til they dry to proceed... Thanks gearhead and LD.. Hey gearhead, hows that case annealing inductor thingy going? been awhile since i looked it up. Any new developments since the timer???

[Gearheadpyro]

Lots have happened since then, JLA. I've got a new induction heater in that costs only 1/3 of the Mini-Ductor, but I haven't fired it up yet. I'm waiting on a few more parts for that.

I've been controlling the heater with a micro-chip that I flash a code on.

I've made a lot of progress on automating it, but am not there yet. I've had several major setbacks in automating, but it's in the works. I've got lots of updates and pictures on my blog if you want to check it out.

[muddober]

LD: May I caution you on what you are going to do with the brass once you anneal it. I was making 6mm/284 out of new 284 winchester brass and thought it would go easier if I annealed the brass first and I used the exact method you intend to use. The propane torch works just fine, however I found that it made the brass so soft that it crushed/wrinkled at the shoulder before it would neck size. As for fire forming I shoot standard factory 375 H&H loads in my 375 Ackley and have never had a problem.

Ron

[LDBennett]

muddober:

We here in California are ruled by a bunch of gun hating liberals who passed a law against 50 BMG guns. But the dummies didn't just outlaw 50 caliber guns they outlawed "50 BMG", expressly. Californians have become good at finding ways around such laws (we got around the assault weapons ban to the point that they are probably the hottest selling guns in most CA gun shops today). So we build the guns chambered for 50 DTC, which is a 50 BMG case with the shoulder pushed back about 0.150 inches, the shoulder angle is changed by about 3 degrees, and the case OAL about 0.060 inches shorter. It is no longer a 50 BMG and is perfectly legal. Of course, the powder charge has to be cut down from the 50 BMG levels (I think, but I have not gotten that far yet). Supposedly it has similar performance to 50BMG. It still uses the 50 BMG case (reformed), the 50 BMG primer, and the 50 BMG bullets.

I'll take this annealing one step at a time and do one case to see if it collapses but the brass is so thick I doubt it will collapse. Thanks for the heads-up.

LDBennett

[JLA]

Originally Posted by Gearheadpyro

Lots have happened since then, JLA. I've got a new induction heater in that costs only 1/3 of the Mini-Ductor, but I haven't fired it up yet. I'm waiting on a few more parts for that.

I've been controlling the heater with a micro-chip that I flash a code on.

I've made a lot of progress on automating it, but am not there yet. I've had several major setbacks in automating, but it's in the works. I've got lots of updates and pictures on my blog if you want to check it out.

Truly awesome work gearhead. I like it