I wouldn't be so hard on the CURRENT Charter Arms company,..as they are not the same company that made your AR-7. The company has change handes a couple time since, and the current folks probably won't even know what the AR-7 is.......much less be able to provide service for it.
What you have is exactley what it is,..or is not. Some were good,..some not so good. Most were bad. I have one that works well with the one factory mag I have for it,..but not worth a pound of bat scat with any after market mag. Many of us have been playing with the AR 7's for years will little success in making them a workable gun.
They were basically a great theory and concept, but one that was poorly executed. It's one of those things you really want to see work,....and ya just keep on trying.
Rumor has it the newer Henry's are better,..but I have yet to see the proof.
I actually tried GenTJWilly's mod with mine,..it seemed to work quite well. I will spend some more time playing with it,..trying to make it work,..and if it does,..I'll be pleased,..if not,..I'll put it away for a few more years,..and try another idea as one comes to mind,..or is brought out by others.
Good luck on YOUR quest for the solution!!