fireforming question

[mikeym1a]

A few weeks ago, I bought a Belgium Comblain rifle. I ordered some 470NE cases to make cases for my new guns. This afternoon, I proceeded to cut off the first case, and mangle it into a faint facsimile of a rifle case. I tried fireforming it with 3 different loads, and the forming did not remove all the 'mangle' marks. I successfully fired the gun 3 times, with the same case, and it, the gun, and I survived.
How do you select a powder, and a load for forming a case such as this? The case is .45 cal. 88gr water capacity. And as the case was a 470 Nitro Express, the side walls of this case are quite thick, .020 at the present mouth. What powders are suitable for a case this big? The case is .575 at the base, and doesn't taper much until you get to the neck, approx 1.6in, then necks down to a very short .454 dia neck.

Any ideas? Thanks.

[Bullshop Junior]

Got pics of the case? You may need to anneal the case before forming.

[mikeym1a]

yeah, thought of that, and did it. No picture of it yet. I'll post one tomorrow. Time for bed. g'nite.

[enfield]

Definitely anneal the cases. As an example I just fireformed some 8x56r to fit the 8x58r rolling block and I used 10 grains red dot ( because I have quite a bit of red dot ) I put about a quarter of a cotton ball on top of that and about 1 to 1.5 cc corn meal on top then use the case like a cookie cutter and fill the neck with wax/lube ( about the same stuff I use for BP lube ). In the big cases you are using you will have to increase the powder for sure but you may have to use some trial and error. ( start on the safe side ). also I don't use as much filler, like corn meal anymore, because it does turn into a solid compressed mass when its fired and could cause some damage, moreso in bottlenecked cases. hope this helps.

[Mod42]

What loads did you use?
Some pictures also. Some types of damage will not be removed with fireforming such a creases in the shoulder.

[paul edward]

Anneal the cases. Softer brass will fore form more easily.

You made no mention of the powder or amount used. Full strength charges ought to fire form your cases eventually.