Having a 338 Lapua Imp and 6.5 x 47 Lapua Imp built and need some load data to fireform brass without sending bullets down the tube. Plan on using cornmeal for filler on top of powder charge. Any help would be awesome.
I can't help you much on this , other than to say I think guys are using pistol powders like Unique. Having said that, I just shoot my brass while doing barrel break in and load developement and fireform it then for my wildcats. Also shoot fireform rounds for fouler shots.
Also, I find that my fireforming rounds are just as accurate as my one fired.