You have the same problem with your recoil reducer as I had with mine. My Merkel .500NE had a round steel bar in the butt to add weight and balance. It was held in by a steel tab screwed to the weight and screwed to the wood with one small wood screw. Recoil caused my wood screw to work loose. I replaced the attachment tab with a heavy piece of steel flatbar and replaced the wood screw with a much larger lag screw. Problem solved.

Don't fill in with epoxy or anything of that sort. You need to be able to remove the steel weight from its recess if you ever intend to remove the butt stock. It's attached by a through bolt that is accessed in the hole that houses this weight.

As for your ejector problem, it sounds like your rifle is doubling when fired first with the left barrel. For an experiment put a primed case in the right barrel and fire a full load in the left to see if the right lockwork is falling. That's almost certainly the problem. It should be an easy fix for someone with the skill necessary. Alex Beer certainly can do it.

Good luck.
Curl