I have a preban poly with a threaded brl. It is not like my other poly preban threaded brl's because it does not have the device that you push in on the sight tower base like my others  to captivate the muzzle nut. No,  it has not been mechaniced on.So what did it leave the factory with a compensator or just a threade brl protector that had no indexing on it? Would it have used a slant and a crush washer or what? The reason I am asking is that it is bare and I want to put what is polytech correct on it to protect the threads! If someone understands this problem I may be using the wrong terms so please correct me if possible. 20+yrs. of collecting and still don't know everything. What's wrong with me? ha, ha! Hammer

drill the FSB for the detent and the retaining pin, drop one in.  simple as that

I don't have my camera this week. Everything is normal about it. It is the poly that has the folding bayo, full blonde wood. It has the threaded brl. in front of the sight tower cause it is a pre-, It's just that the sight base ain't drilled and tapped with the plunger and spring. I thought this may be a model that used a factory comp or  some sort of crush washer and a break or just one of them smooth thread protectors? Is there a place I can research different poly models with pics? I could put any break or muzzle nut on there but I would have to tighten it against the tower base and I don't mind doing that if some were done this way. I just like some weapons to be correct. Thanks, ..............Hammer

Well if you get it sorted out and need some parts here you go:
www.globaltrades.com/ak_sights.html

Oh come on, I know somebody has seen this!