I just got my SUB2000 back after being gone for 3 and 1/2 weeks for the recall. Went out to check function and site it in. After firing a full mag. 10 rounds. The collar that goes on the back of the grip frame had backed out till it was sliding on the receiver tube. I put it back on and it done it again before 10 more rounds were fired. What is supposed to hold that collar to the grip frame? Looks threaded but there is no threads on the grip frame. I hate to send it back again and have them keep it for no telling how long.