Fits arsenal - just barely - FAB Defense AK/AKM Picatinny Scope-Mount Dust Cover

Installing on an Arsenal milled receiver it seems the forward lip was just a micron too thick to allow it to go fully forward. Did not want to touch it with a file, voiding any return. Gave it a few whacks with a firm rubber mallet, so close but no luck. Took it to my gun guru. He fiddled a while, then finally grabbed a nylon hammer and started giving it the baby seal treatment. I was beginning to freak out a little, but relieved when it snapped into place. Followed up with very light file work. A bigger hammer is always the answer.