I have done some searches, just want to make sure I have the "recipe" right. I want to fire form some .375 AI cases from .375 H&H cases (and am trying to avoid doing reduced loads with bullets to form). Sounds like you take a primed .375 H&H case, add 15-20 grains of Bullseye, then Cream of Wheat to the neck. Where I get a little confused is, some folks say to just take toilet paper and stuff in the neck, others say seal the neck with wax, soap or Crisco, and others say stuff it with a piece of a packing peanut. Does it matter which of the methods you use to fill the neck? Also, some say shoot vertically others imply that it makes no difference how you shoot. Do you need to hold the rifle vertically? Thanks.

Mike

No, it makes no difference if you use toilet paper, wax or a little cardboard cutout to hold everything together, and top the end off with. 15-20 grs of Bullseye is good, Cream of Wheat, or similar, I use corn meal myself for such duties. It's all a mess, but very effective in many cases. No, you do not have to hold the rifle vertical to do this, but you do need to point it in a very safe direction, as the load is rather destructive at close range, just shoot outside into the dirt bank or berm.

I have a little instruction page on the B&M website below is the direct link, it might help some.

http://www.b-mriflesandcartrid...om/Case-Forming.html

Now, for the forming you want to do, I really don't think this is going to get your shoulders as sharp as you would like. While this is a very good method for blowing 375 HH out to say 458 Lott or 470 Capstick, something with shoulders does not get quite as sharp as I would like for them to be. Just give it a try, and see for yourself, maybe it will in your case.

Something else as well, I have heard a lot of crap about pressures being excessive--it's crap, I have done pressure traces on the 500 MDM blowing out cases, tried many of them and could not even get a reading, meaning little or no damned pressure at all. I did get a reading on one, it was around 12000 PSI or so, so unless you fill the case full of bullseye you won't have a problem. I use 15-18 grs.

Michael

I used wax when I started. Found it not needed unless you were going to really bounce your brass around not in a nice blastic box before you fired it. It would simply help keep everythng in place.

The shoulder might not be perfectly sharp but your new higher capcity will be there so load them as AIs and the shoulder will be perfect the scond time.

Parker Ackley said to just use a good "snappy" load.

First- Its a .375 H&H AI, right? Why not just shoot some factory .375 H&H in it? Thats the easiest way and you'll get sharp shoulders!
If you dont want to do that then first try bullseye alone. Start at 20 grs, nothing in the case and hold the gun straight upwards when firing. If the case doesn't fully form, go up 5 grs at a time till it does. If you reach 35 grs and if it still isnt working, back down to 20 grs add cream of wheat and "stick the case mouth in a bar of soap to close it off" Fire this pointing upwards. Again keep going up till you get a fully formed case. The shoulders will still be slightly rounded and won't fill out till you fire your first load in that case. Can't even remember how many wildcats I've done this way.

I've been doing this wildcat thing a very long time...longer than most, not as long as some. I've done just about all the things the posters have suggested and a few more...used 5-6 fast burning shotgun and pistol powders, 10-30 gr depending on case size...usually with cream of wheat, but also with several other hot cereal grains...grits, polenta, cream of rice...whatever grain or powder I happened to have on hand...THEY ALL WORKED.

I tried the wax thing way the heck back, then canning parawax, soap(Ivory seemed to work the best back then, but the little, thin bars from motel/hotels were even better) but finally settled on just a 1" square of paper towel rolled into a ball and pressed into the neck level with the case mouth...quick, easy to do, cheap and worked.

BUT...I never got a sharp shoulder fireforming this way...only on the second firing of a mid-range load during load workup OR if it was an Ackley chamber, firing a factory load.

TONS of fireforming data on this site and about a thousand others...do a search, it's fun.

Do what Rob says...point the barrel UP AND DOWN WIND...and wear a cap, otherwise you will need a hair shampoo.

Luck

Mike, I shoot a 257 AI, I don't like wasting time or powder, so I load new 257 brass with a starting 257 AI load for a recipe I'm building and it is off to the range. I come home with fire-formed brass and range data to continue developing the final recipe. It works for me.

The only reason I would consider the method you mentioned above was if I wanted to FF brass in my back yard.

+1

I'm fire forming for my 375 Weatherby (basically a 375 AI with a Weatherby shoulder), using full power 375 H&H handloads or factory ammo. Works great.

I have been shooting cast bullets (gas checked)in my Mauser. NEI mould, 310gr, 21gr of Unique. Quite a snappy load, and forms the case fully with one loading.

Rich

I prefer to use a two grains below book max loaded .375 with cheap bullets like Sierras or whatever extras I have around the shop..the make excellent break in loads, and off hand practice and they fully form the case..

I have used parafin over cornmeal and its OK if you want to go that route..