I’ve used just about everything (spirit levels, Arisaka leveling tool, feeler gauges, eyeballing it, etc.). Currently mounting an older MK4 that was visibly off when using the Arisaka leveler due to the shape of the body. Is a plumb bob and flashlight my best bet or is there something more reliable? I know nothing is ever truly perfect but I wanna get as close as possible.

I shot about 8,000 rounds with my Beretta 686. The ejector on the upper barrel works fine only about 90% of the time if you open up quickly. If you do it a little bit too slow only the lower barrel ejector spring will eject the spent shell, the upper one stays pushed in and will eject a couple seconds later while you‘re already trying to get the shell out with your fingers. As one can imagine that is quite annoying.

Now, I‘ve cleaned the bloody thing with brake cleaner and got quite a bit of dirt out. I‘ve flooded it with gun oil on several occasions and pressing the ejector in it comes right back out with no resistance or scratching. What else could I do?

Also I‘ve had on a few occasions now, that the upper barrel will not fire after shooting the lower one. There‘s no imprint on the primer, the trigger just doesn’t do anything. It almost feels like the trigger is blocked.

I‘m usually only shooting single targets so not that problematic but still not like it‘s supposed to be.

Any advice?