My experience with a Irwindale made AMT Back-Up was in the early 90's and it was a jamb o matic, I really wanted to like this solid gun, but I just couldn't get it reliable. Some have had good luck so I would say for $100 I would give it a try. AMT has been sold many times and now High Standard ( IIRC) Has now bought them, not sure if the internals are still the same as the earlier ones so parts may or may not be available for it, just so you know.
NCH