Me too. Except that it was a bit difficult to retract the bolt on the simplified later version M3A1 when wearing gloves. That was a problem during my first hitch, as a young tank crewman in Germany, less so my second time out of the cage during my tour of the spas and cathouses of Southeast asia.
The only real problem I had with the things was that the GI issue 3-cell magazine pouches were in short supply. In germany we used an *engineers bag* pouch with eight mags to cure that problem. After I found out how much ammo I could go through when I missed a lot, I started carrying 15 magazines in a GO *buttpack* on a wide strap sling over my other shoulder.
He missed riding in tanks in the SEA festivities, so didn’t have to deal with keeping the M3 fed in times of serious need. By that time he had gone Army Aviation and flew Caribou out of Can Tho. Don’t know what he kept in the cockpit, just thinking about it, and he’s not around to ask (he came back from VN, died after retirement).
Your answer on keeping the M3 fed looks like a good one to me!