My response is DON'T!!! The rule with the Nylon 66's is, NEVER disassemble. You'll never get it re-assembled. Clean bore from the muzzle. Any disassembly requires the services of a qualified gunsmith.I've taken off the center cover, but don't want to dis-assemble any more unless I have to. Thanks.
Sounds like your firing pin was stuck in the forward position from powder residue, or something like that. AFAIK there are no nylon parts on the gun that could cause a slamfire. The receiver was nylon and incredibly durable, and the bolt and internal fire control parts were steel.Got rid of mine when it started slam firing 3 round bursts (full automatic).
Guess the nylon parts weren't as reliable as touted back then, and why they are no longer made. Think R51, etc...