My fire form load is 22 gr. of H-110 behind a cheap 150 grain bullet - buy them in bulk from Midway. Any bullet weight will work, just make sure the charge is high enough to give a crisp angle to the shoulder juncture. I never have been real big on using cotton balls and/or corn meal to fire form.

Make sure the headspace is set properly - so that a virgin brass case or factory round chambers with a little "umph" on closing the bolt. Otherwise, the firing pin can move the case forward a short distance before the pressure blows out the body and shoulder. This will cause the case to weaken at the web and separate after a few firings. Cure is to simply set the barrel back a little - usually about .006 to .008 if the gunsmith tried to headspace it with standard .280 go/no go gauges.

The powder to use, once you get casesfire formed,is RL 22.