Help with the right chamber

[luke79]

Thanks for the info Kmon I follow ya on the mag deal. I'm actually considering modifing my CZ mag a slight bit my plan is to mill out an aluminum block that is the same deminsion as the inside of the mag shape as well only I'll make it the length I want and put a slight taper on it so it'll start in. Then heat the very front of the CZ mag in hopes it'll stretch as I press the block mold thru it till it reaches the top. I'm only talking from 2.3 to 2.45 possibly. Hey its an idea this is a custom gun that's all mine it may screw up the mag but they make more. I thought it would be worth a try. I'm hoping to push the 130gr JLKs fast enough to reach 1000yrds supersonic. Do you guys know the velocity needed to keep a 123gr Amax supersonic just beyond 1000 and the SMK as well I imagine there both the same or very close.