Threads were significantly more expensive, both for the pin and the caps. Guns were made to highly competitive price points. Even a small cost saving on a lagre lot of guns was worthwhile for the maker. Remember, also, that we are using many guns way, way past any timeframe imagined by the maker. The more ordinary original quality grades of guns were just not envisioned as being kept in service for a very long time.
Disposable shotgun? Well I suppose that could be. Perhaps we'll eventually have a disposable automobile and a removable crankshaft won't be required.
Jim
