08-19-2020, 02:51 PM
K39,
the pin also keeps the barrel extension, and barrel, from rotating during use. when the big fire lights off, the bullet hits the rifling and starts to rotate to the right, assuming right hand twist. due to Newton's second law, the barrel is trying to rotate to the left at the same time. i don't know if the barrel nut will keep the barrel extension pressed into the upper with enough friction to counter the rotational torque placed on the barrel when the rifle is fired. i wouldn't count on it myself. if you try any welding, you'll need to get the extension, and perhaps the barrel re-heat treated. i would suggest, as A5B noted, that you do need the pin. since i don't have the tooling myself to install a new one, i would take it to a gunsmith if it were me. ymmv.
-tdbru
the pin also keeps the barrel extension, and barrel, from rotating during use. when the big fire lights off, the bullet hits the rifling and starts to rotate to the right, assuming right hand twist. due to Newton's second law, the barrel is trying to rotate to the left at the same time. i don't know if the barrel nut will keep the barrel extension pressed into the upper with enough friction to counter the rotational torque placed on the barrel when the rifle is fired. i wouldn't count on it myself. if you try any welding, you'll need to get the extension, and perhaps the barrel re-heat treated. i would suggest, as A5B noted, that you do need the pin. since i don't have the tooling myself to install a new one, i would take it to a gunsmith if it were me. ymmv.
-tdbru