Got a M3A1 barrel for a project. But I think that the chamber look...a little short. 



Is there anyone here who would provide a pic of a chambered round in a known good M3/M3A1 SMG barrel ? 

Thx ! 

That's not right. I just took a look at mine, and the base of the cartridge protrudes .190" from the end of the barrel, when chambered. (About even with the front of the cannelure.)

You have an unfinished barrel -- barrel nut not installed, and chamber not finished reamed. I once saw one of these barrels, in similar condition, that had no chamber at all.

How do you plan to install the barrel nut?

I drilled the old pin from the barrel and I milled the new barrel for a slightly oversize pin. I still have the old barrel on hand but the chamber is bulged to the point the headspace gauge will not enter. I think I will cut the barrel in half to measure the length of the chamber :-)