Re: Need loads for 22-243 AI w/ 75gr AMAX
Wayne McD, About 35 years ago, my gunsmith advised me when fireforming cases in an improved or wildcat chamber to use what would be a maximum load in the parent case, and seat the bullets to firmly engage the lands. Since then I have fireformed at least 2000 case using that principle, but acknowledge that many have fireformed cases successfully without using a bullet.
One thing you will notice that if the fireforming load is not stiff enough, then the shoulders will not be formed correctly, and you have to do it again, which is a pain.
Also in the fireforming process the cases will shorten, and probably between .010 - .015 inches, so don't trim the cases before fireforming, unless you have to do so to chamber them.
I would have thought that a load of about 43 grains of Re 22 with the 75 grain Amax should be ok for fireforming. That load is about maximum in my 22/250 AI, with the 75 Amax, so it should be safe enough in the larger 22/243AI.
Once fireformed, Re 22 will probably give good accuracy and velocity with the 75 Amax, however, I would also be trying slower powders such as Re25, H1000, VihtN170, to achieve a 95- 100% loading density, which from my experience makes it easier to find an accurate load. Regards, Brian.