You guys sure got the right answer, and right away too. I saw a 30 Kurz conversion of the M1icon carbine back in the 70's, had a new longer barrel
installed and the bolt face opened-up. I thought it was too much for that carbine action and would never even consider shooting one. The Johnson
and similar 22/30M1 carbine conversions work out without much trouble (3000 fps from a 40 gr bullet). Another conversion was the Vulcan pump
action M1 carbine in 44 Magnum !