The front trunnion is below the RSB on the inside of the receiver. I have a WASR that has the same issue, same scraping of the carrier. Still shoots fine, so Im in no hurry to fix it. I did though, put mine in a vice with blocks and hammer the hell of the RSB (rear sight block) and moved it back a good bit. The real way to correct the issue involves a press, if you have one then no problem. There is a pin on the bottom side of the RSB you knock out, then press the RSB off, redrill the hole for the pin a little larger, adjust the RSB correctly, press back on, then use a new larger pin to drive through your newly larger pin hole. Seems like a lot of work, so I went with a vice and blocks and a 3lb sledge wrapped in an old tshirt. AAHHAHAH did the trick though. Its not perfect, but using the irons, I can hit dead center at 200 yds