Locking back

[Foxhunter]

So when I was ready to throw my r51 in the lake, due to constant jamming due to rounds diving into the loading ramp, I found this site. I found instructions on how to trim the magazines and polished everything. I put the gun back together, but every time I fired it the slide stop would engage and lock it back. As a last resort, I disassembled and reassembled. It racked and shot perfectly. No more jamming. I am happy, but I still can't figure out what was making the slide stop engage. Anyone know what I did wrong?

[scouts owner]

There is a very small spring on the left hand of the slide that causes this problem. On reassembly it must be properly engaged to prevent  locking open. Several youtube vids on the subject..
Its the first thing I check after disassembly. .

[sebvox]

Foxhunter - glad you kept the R51 and took the time to fix the issues.  Scouts Owner is correct that the slide release was the culprit.  When reassembling, the catch must be under the little spring or it will lock back on every cycle.  Here is a video that shows the issue: https://www.youtube.com/watch?v=jwUyxp0kNQg

[Foxhunter]

Thanks guys. I actually feel comfortable enough th carry it again. It won't shoot 9 mm rat shot, without jamming, but most semiautomatics wont, so I am happy

[Zenshot]

Once you get the hang of disassembly and reassembly, it's easy and reliable.