Its easy to strip and then reassemble them its the balancing out the non regulated guns I've had most problems with. But the ones I've had have all been fiddled with and 2 of them came in carrier bags and a third one had the safety played with and the daft sod who sold it to me wasn't using the trigger to fire it but the safety, and he thought that was OK. That was the only one that beat me as I sold it without the safety operating, the guy who bought it said he had a few and one of his other guns didn't have a safety. I searched high and low for a replacement sear but never found one, even Geoff at Gunpowder didn't have any spares as it was a very early gun and the sears or parts of them changed through the years.
Now I have fitted a reg to one I wouldn't hesitate to do it again if I had another, you get more consistent shots and the power doesn't fluctuate.