^^^That's a cupseal, and has nothing to do with recocking issues.
Try replacing your striker o-ring as well, even if it doesn't look damaged, give it a try. 9 times out of 10 when my Zeus or WS-66 won't recock is due to a striker o-ring being bad.
UL'd Black DM5
I want clear DM5 eye covers, PM me if you want black covers.