[bushmaster1313]

It seems like the older riot guns traditionally had 20" barrels. This makes sense for the Winchesters in order to clear the six shot magazine. But the Remingtons and the Stevens could have had shorter barrels.

Today we see 18 and even 14 inch barrels

[CajunBass]

Probably because they were thought of as short enough. Back in the day, shotgun barrels were longer generally, probably a carryover from the black powder days. Even when I was younger, 28 and 30 inch, barrels were the norm, so 20 inches was a shortie.

[Virginian]

That was before the internet and the loss of good taste in the land.

[KarbineKrazy]

What about all the old sawed off doubles that helped win the west?

[Youngster]

Really short barrels are "blasty" and don't point all that well IMO, it's not all gravy. I own one and I tend to think of them as sort of being the shotgun equivalent of a sub nosed barrel on a handgun, more of a specialized item.

[oneounceload]

What about all the old sawed off doubles that helped win the west?

Most weren't that short - muzzle blast and lousy control-ability would result

[4sooth]

Shotgun barrels are/were shortened to make them handy in confined places. Imagine try to maneuver a 30 inch barrel in a narrow hallway during a SWAT raid or just confront a bad guy in your house. Or get in and out of an auto quickly.

[ArmedBear]

Bear in mind that a "riot gun" was not designed for SWAT, but to stop prison riots in a time when the guards would not have incurred any unnecessary risk to avoid shooting people. If in doubt, I'm sure they just stood at the end of the hallway and started firing buckshot rounds if things got ugly.