When a pistol upper is sold as a 10.5" is that measured from the bolt face with a dowel pin dropped in or in some other manner?

All the 10.5 pistol barrels I see on here appear to be kind of long


I ask because I was considering having a barrel cut down on my .22LR upper to add to a dedicated Pistol lower. If I ask for 10.5", how much will actually stick out past the barrel nut? Is there a "too short" length?

Blow me some crap if you must, but I may add a Spikes fake can and I do not want a 16" overall length barrel when done. The can I am looking at shrouds the barrel a few inches and I plan to factor that in. The 22 upper is a cheap Chiappa that I don't mind messing up. That said I don't want to completely destroy the upper or get in hot water by having cutting too much off.

Many people will say go for the 4-4.5" range so that bulk HV .22lr stays subsonic, in case you want to add a suppressor later.

On a standard 10.5" barrel, there is ~2.5" of barrel in front of the carbine gas port location, plus a muzzle device.

There is only a difference in external length if you go with a dedicated .22 barrel that has the integral collar, so the breech is actually further to the rear than on a standard AR barrel.

Stated a different way, the same length (yea, I know) .22 barrel is shorter by the difference in chamber length between a .22 and a 556 round.

Got it, many thanks!