You're right. From, say 1961 or so onwards, when all of the initial in-service teething troubles had been worked through, such as crap method of attaching the gas cylinder, razor sharp edges on the cocking handle slide plus a few others it was a good reliable work-horse. I just left my gas regulator fully closed, max gas and it just banged away constantly and reliably - like my first girlfriend.
At the end of their life there were some pretty-well worn out ones floating around that were really beyond salvation
Added later....... I thought a few more would add a 'thanks', if only to smile about the banging away reliably like my old girlfriend comment. Oh well......