We had what I assumed was a Canadianlegal M-1 carbine come through the shop. It has 2" of free-bore barrel added (welded) to make it over 20"
On another note, I replaced the Mini-30 factory firing pin with one with a .045" protrusion from Firingpins.com to have 100% ignition on Russiansteel cased ammo. The primers are inset a tad to prevent slam-fire on full auto. Mine gobbles up anything! It is a 584 series, so it has the heavier barrel and front post and wing front sight and ghost ring rear sight. Sight picture is identical to M1 Carbine, M16, M14
, M1 Garand. Much better than the old mile high front ramp and folding leaf rear the PRE-2006 Mini-30s used to have. Takes Ruger receiver mounted scope rings like the Ranch rifle, too.
Besides the M1 Carbine and Mini-14 and 30, I have AR-15s, and have had AKs. I have to say, my first choice to grab as a WTSHTF defensive carbine would be either the Mini-14 or Mini-30. I just shoot them really well....