Marcum

There are a few ways to diagnose the problem and multiple things could cause the bolt catch problem. First thing to try is take out buffer and spring and bolt carrier. See if bolt catch moves as it should with upper on the lower. If it does then the problem is buffer, buffer spring, or buffer tube. An AR10 /LR308 carbine buffer tube is longer than an AR15 buffer tube. One that works is mil-spec UTG pro AR308 extension tube. Cheaper than dirt has them. The buffer should be 3.8 oz. and 2-1/2" long. Back to the bolt catch. If the bolt catch doesn't move as it should without bolt carrier in place the bolt catch is hitting the upper. To correct the problem either take it to a gun Smith or use a drimmel tool and carefully take off the material where it is touching. Make sure you put a rag in chamber area to prevent anything intering barrel. Keep checking to see if bolt catch starts moving so you don't take material that doesn't need removed. Most likely it will be in the areas where the rounded corners are above the bolt catch. I bought 5 buffer tubes that claimed to be for LR308 AR10 before I bought the one that works by UTG.