Re: For those w/o time in the military:
"a rifled barrel is not easy" - Oh yes it is. Very fucking easy.
In terms of repeatability of the fired rounds grouping accurately at predetermined target ranges, from;
a) The same barrel and or;
b) A group of barrels made by the same maker the same way.
And most killing is done at short to modestly short ranges.
But it's possible to have a not very good barrel group reasonably accurately, where most of the shots land 3 meters to the left at 100 meters...
Just dial the scope in....
Watching videos of the 3 and 4 and 6 inch smoothbore cannon with the round balls on Youtube - they are placing fairly accurate shots at human sized targets, like a mile away or more.....
And smoothbore guns......
The only real differences are incremental improvements, in the bores, the ammunition, the rifiling and propellants, that give flatter trajectory, better targeting, higher accuracy at greater ranges....
While a really really good barrel and overall gun for say a sniper, may in fact be a fabulous piece of work, not many people are shot by snipers in the workplace, or at night clubs, or in criminal acts or in reprisals by people with sniper rifles....
Even a shit gun with a shit barrel will do nicely thankyou.
But a really good barrel, is actually fairly straightforward to make.