I was thinking about the cartridge case and yeah there usually is air space more if you do a low grain load, when I made my own loads, saved a ton on ammo, anyway you have low grain load medium and high. I would do the low since I was usually making target loads. Met a guy at a gun range and we good talking about reloads and told me he never got a reloading manual. So I said how do you know how much powder to put in. Told me he would fill the case to the top and force the bullets down. Wow I said isn't that dangerous. Yeah he said blew the barrel off his gun, damn did you lose any fingers. No he says got some first degree burns got lucky and learned a lesson and bought a reloading manual. Used to be so great the great western gun show used to be local got huge deals on guns and ammo. But California cracked down on gun show's and the gun show moved to las Vegas.