I had 1 M1 carbine in supposed 5.7 Johnson. Wildcat by the time I had it. Pain in the ***. Had to make brass , had to figure out loads. Note none of the published data worked, They blew cases to the point I worried about the guns safety.
Finally experienced trial and error loads the was working the action and not showing pressure signs. By that time the loss off brass hard made became to much. I sold the gun.
I thought it would make a sweet little varmint rifle but it was fantasy. I replaced it with Mini-14 and downloaded the rounds to the point the action still worked. It weighted 8 ounces more than the custom M1 carbine.
I still have an M1 carbine for my son. He does not shoot it but it's in his safe.
I also had a Winchester M2 carbine on an NFA stamp. That gun was useless IMHO 3-5 round clime would be over a 12 foot backstop. Sold it for a big profit. Don't miss it whatever.