I tried the vari-flames. The Mustang would not ignite the primer. My brother-in-law's Knight Disc would not set them off either. We tried both CCI small rifle and Winchester small pistol primers and never got a pop. Don't know what the problem was. Was thinking it had to do with the shape of the firing pins in those particular guns, but that can't be the case because the Mustang sets off the CCI's just fine with 25 ACP's. Maybe we got a bad batch of vari-flames. Pretty sure we had the primers seated right in them.