RE: New Mossberg 935
The malfunction of gas operated guns with locking blocks when you first get them is caused by collective tolerances causing the locking block not to lock up until you have fired several boxes of heavy loads thru them: i.e 1100's, 11-87, Mp-153, Mossy 935. I check this out after thoroughly cleaning the gun and reoiling lightly by moveing the the bolt forward slowly. If it doesn't lock up I hone on the end of barrel (tool marks) that goes into the receiveruntil it does lock up, then you do not have to break it in. I had to do this with one of my 1100's and the MP-153. Ned S