I was given a Remington 31 pump gun in 12 gauge the was held together with electricians tape at the take down barrel nut deal. I took the tape off and found that it was missing a pin/screw thing which I had to make as Numrich did not have them. So I am trying to put it back to gether and find that I cannot get the barrel to lock up properly and think that I may be missing some other parts as well, maybe a spring. What I have now is the mag spring, the mag spring retainer, the home made cross pin/screw and the knurled "nut" thing. There are two pins on the barrel lug that seem to want to line up with holdes in the knurled nut thing but I can't get the "nut" to move forward enough. I have not been able to locate any exploded drawings on this gun. Anybody have any links to a diagram or any other insight that might be helpful to me? Thanks!