Anyone been able to get one of these apart?

I've got a brake from a 110 FCP that I want to screw on here, and it came with a crush washer for timing the brake.

The problem is... I can't get the corresponding original washer *off* the gun, and not for lack of trying. Penetrating oil, gripping it as gently as possible with pliers, tapping with a cold chisel at the seam between the 'washer' and the barrel... nada. It ain't coming off.

I'm starting to wonder if the dang thing isn't really a shoulder machined on the muzzle tenon... which makes little to no sense as to *why* they'd machine a tenon that looks like a crush washer?!? It would make sense that they used a crush washer to time the 110BA brake like they do the 110FCP... but that thing is on there like its all one piece.

Anybody?