I have come into a Merkel Model 8 12 ga. It is rather ugly in all ways and is missing the Greener top bolt. The gun locks tight and has been used this way for some time. This gun already two bites locking below. In anybody's real world opinion, are the Greener bolts really necessary and is it safe to shoot as is. This is not a gun I want to put any money into. BTW, I have a spare Mod 8 receiver I could cannibalize for parts if necessary, but would have to shop out the labor to a competent mechanic.