It looks really good and it feeds! I don't mind at all that you welded the pivot on but I am dissapointed that you didn't keep the combination red carry handle and pivot pin. (Mustang Carry Handle). LOL
As far as the gas relief holes in the gas tube, on all three of my belt feeds I had to have a very gas tight joint there and relief holes almost at the end of the stroke. You basiclly have to convert a short stroke gas system to a long stroke system in order to push the BC back all the way and actuate the feed cam. You might be able to do the same thing with a large gas port in the barrel. The 308 is a lot higher pressure than the 7.62x39 and may have enough impulse to through the BC back all the way with the standard setup. I believe DTM has some experance with this in his XT74 which shoots a high pressure cartridge.