I had a 5" Hardballer. Bill Thompson did a trigger job on it for me. He fitted a barrel bushing and a new barrel link on it. It shot fairly well after that. Never had any problems with it after that.
It's kinda hit and miss with the older AMTs if you got a good one it was great,if you got a bad one it was a nightmare.
I don't have any experience with the pistols made after the original company went broke and change hands 3 or 4 times. They were sold as IAI and other names too.