So I picked up a Rob Arms M96 off gunbroker which arrived a day ago. After handling it for about 10 min I noticed a hole that someone has drilled through the upper. Kind of irks me that I didn’t notice it on the GB listing. Any ideas on why this was done? The bolt rides behind the hole so anything that was through the hole would prevent it from cycling. Any ideas on a patch repair to clean it up? My first thought was to get a pin, like the ones on the gun, and use it to plug the hole. However, as stated the bolt will not allow it..