I know what I know but I don't know what I don't know. Have two Ingrams but know little to nothing about the STEN market. The MAC family is pretty forgiving in that (with the exception of the Texas M10) parts are readily available and the guns are easy to work on; hard to go wrong. Is it the same with the STEN or are there ones to be avoided? Looking at one built on a CATCO tube but it looks pretty home made which has me a bit apprehensive. Anything I need to be mindful of?