I'm thinking about opening up my 22-250 chamber to an AI not for velocity but to get away from case trimming so much but I don't want to prematurely shoot out my barrel fire forming brass. Who is using or has tried the cream of wheat and pistol powder method of forming cases, does it work ok and if so what is a recommended charge for the 22-250. The downside I hear about this method is premature case head separation, is that a real concern?
thanks

I wouldn't dork around with Cream of Wheat for something so minor. Get your chamber Ackleyized properly -- emphasis on PROPERLY -- and work yourself up a good shooting load. Hunt with that load through the batch, and then you'll have your fireformed cases.

so what are the cornerstones of a "properly" AI'd chamber?
I don't want any mistakes if I decide to go this route

I have yet to not find a good hunting load for fireforming.

A properly chambered Ackley should have zero headspace on virgin brass.

I used 17 grains of 700X without cerial, but a 1/4 square of butt wipe rolled up and stuffed in the case.

Dude, Six and aalf are about right.
You should "feel" some snugginess with virgin brass (preferred) or FL-sized cases. Not "cranking" the bolt down shut, but you should definitely be able to feel the camming surfaces doing the job on final close.
If the bolt just closes without any feel, then you might have a headspace issue, which is something you want to avoid.
You will know if you have a headspace problem if the primer moves out from the case base and/or there is a ring near the base and inside the case that you can feel with a bent paper clip. If you have factory ammo, one or two rounds test firing will tell you immediately whether or not the AI was done correctly.
When going for "feel," I keep my bolt lug faces lightly moly-greased to prevent long-term galling of the surfaces -- but that's just me. Don't let the grease slop around anywhere else, however.

I use a similar method but use a plug of soap and a fast pistol powder instead of cream of wheat.
Experimenting with the charge weight is fun, use only enough to get a full case blow out and sharp shoulders. The risk of high or excessive pressure is very slim, if not at all.

Cheers.

I did the cream of wheat method when I first got my 7mm08 Improved but I doubt that I would again. It was messy and slow but It did produce good results. Now I think that I would just load some bullets and go shooting. miles

Load a max charge, seat a bullet and go shoot.

An Ackley chamber should have approximately .004" less headspace than it's SAAMI parent, that allows factory ammo to work and provide a crush fit. That crush fit prevents the case head from moving back and stretching in that area.

Cream of wheat is great if you're forming cases with a larger neck diameter, such as making .250 AI cases from .22-250 cases.

But in this "case", making .22-250 AI from standard .22-250, the others have given good advice - just load the standard cases and shoot.

I'll agree with just firing standard rounds in an improved chamber, but there is a small niche where fireforming with COW (or something of that ilk) has a place.

I shoot an old pre-war wildcat, a .22 Maximum Lovell built on an altered single shot Krag action. The cartridge is an improved version of the R-2 Lovell, based on the old .25-20 Single Shot case. Brass is rare and/or expensive, and I don't like to start the countdown clock for case life ticking any sooner than necessary, so I fireform first as gently as possible (after annealing) with pistol powder and COW. A bit messy and case fill-out isn't quite 100%, but I achieve a case that's not stressed by its first full charge firing, gaining me (I think) one more notch on the case life tally. Am I all wet in this approach? My gut tells me no, but I have been known to be wrong once or twice in my life!

Rather than go through the rigamarole of providing a pic of this cartridge, just Google .22 Maximum Lovell to get an idea of whence I speak. I do have a pic on file of the rifle:



Note the Pacific double set triggers. Push the front trigger forward to set the rear trigger. (It won't fire un-set.) Rifle was built by Hervey Lovell himself, and marked as such on the barrel and under the buttplate. A bug hole group maker, with ballistics in the .221 Fireball/.222 Remington realm.

I use pieces of waded toilet paper & pistol powder to blow out cases. Wouldn't suggest this over a field of very dry grass!

Dude, if you are not already confused, a "properly" reamed AI chamber will have a "crush" fit on new brass. You WANT to feel some resistance. I am repeating Jim and others on this statement so you will understand that you want to repeat to the gunsmith that you absolutely want a Crush fit. DO NOT mention that you want to shoot factory ammo, or the gunsmith may botch the job. I tell my gunsmith that I want the crush fit to the point to where I do not want factory ammo to chamber...you get his attention with that statement. If he does not know what he is doing, he act confused...hint.

I have a lot of AI's in different calibers. I work up a fireforming load and hunt with it. The FF load will be hotter than a load for a std 22/250.

I would not AI a Barrel that has a lot of rounds down the tube.

I fire formed 1000 cases in an afternoon with cream of wheat and bullseye in a factory barrel that was intended to be used for forming cases only. I got the barrel so hot, I just dipped it into a 5 gallon bucket of water to cool it. After all that fire forming, I cleaned the barrel and just for grins, worked up a load in 12 shots using Win 760 and Sierra 55g BTHP, killed a bunch of coyotes with that barrel.

As I said earlier, I now hunt with fireforming loads, instead of the cream of wheat FF. If you feel that you are less of a man by hunting with fire forming loads, then by all means, use the cream of wheat/bullseye and have at it.