doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Annealing brass

Is annealing necessary? The pressures of .410 are considerably lower than rifle pressures. Gil

Why not cut the parent cartridge to length, anneal as required and expand the case with the appropriate diameter mandrel? Little or no fire forming required.

Scratch the trimming idea. The parent case is just shy of 3”. I still think the neck can be expanded to sufficiently…..I may try that in a few days.

I've never reformed brass cases, but I'm a metals nerd, and, from what I've read, when expanding a bottlenecked rifle case into a straight-walled case of larger bore diameter, annealing is necessary to prevent the cartridge from cracking or splitting at the case mouth. Because the simple act of bottlenecking what was originally a straight-walled tube during the case--forming process at the factory, has already work-hardened the brass somewhat. De-bottlenecking it means stretching already-stressed metal. It might not like it without being stress-relieved first.

Nothing to do with the chamber pressures.

I of course invite correction from those who've done it. I'm here to learn.

Going from 9,7 mm to .410 (10.414mm) is an expansion which isn't that significant considering that 9,7mm is the round's diameter and not the case's mouth diameter. A buddy and I fireformed over 200 5.56mm rounds to 7mm without annealing. We shot the 7mm TCU round in competition. I don't recall any problems. Gil

If you are worried about consistency, and have a thermometer, you can do the old stove pot, filled with sand, on a camp stove or hot plate. You can control the temp., depth, and time if you want? I'd hold it in my fingers, and I would drop it in water, again for consistency. Whatever you do to the case, will stop on the spot.

I'd lean towards lesser annealing, maybe like Ken's picture? With good brass spring back, you may never have to figure out how to resize the long case. I'm assuming overshot card, maybe needing a relatively heavy crimp, so just a bit of the mouth may appreciate regular annealing. Only thoughts, best of luck with it.

When expanding .30-40 Krag cases to .38 caliber, found the shoulder would collapse if annealed beforehand.
Expand neck (Good lube in required) first, then anneal, then size cartridge.
Chuck

Stan,
If you hold the cases in your fingers, by the head, and turn(twirl) them in the flame of a torch it is not possible to hold them until the heads are hot enough to anneal. Steel and brass work differently when annealing. Somone mentioned annealing cases causes them to buckle at the shoulder. This is a valid consideration, especially if the necks and shoulders are overheated and they are being expanded with the sizing die's expanding button. If overheated, but fireformed, buckling will not occur during the initial expansion. In severe cases of overheating and fireforming buckling may still occur when the expander enters the neck during the sizing for loading. This can be reduced by lubricating the inside of the neck and/or using a tapered expander. Generally, this sizing and the subsequent expansion when the cartridges are fired causes enough work hardening that buckling is not likely to occur afterward.
Mike

Thanks again, my friend. I do intend to expand the necks by fire forming, so shouldn't have any problem with buckling as the forces involved will be acting in different directions than when using an expander button in a die. I had watched a video showing how someone used a torch and did it as you say, by hand. That is the method I will use. I may do a few this morning, load them up, and try the procedure. To be continued ........

Just a thought, I'd fire form by shooting the way it's intended. Even if the payload is less than when the case blows out, it can still be shot at clays or what ever.

A cousin, an inventive guy, converted a 94 Winchester to 2.5" .410 and used Marlin .4xx brass. AIR, he only needed to trim the case length - no annealing or fire-forming.