Switch-Barrel: How Do They Work?

[killshot44]

One pin or two, you're still "locating" the lug in relation to the lug recess. No reason why one wouldn't work. Same principle.

Granted, I've never seen a one-pinner but it should achieve the same result.

[ar15barrels]

Switch-Barrel: How Do They Work?

One pin or two, you're still "locating" the lug in relation to the lug recess. No reason why one wouldn't work. Same principle.

One pin locates the lug as well as a lug alignment tool locates a non-pinned lug.
It does not locate well enough to switch barrels in a fully bedded gun though unless the barrel is fitted perfectly inside the lug.
See the illustration above for how the lug can get out of alignment if there is play between the lug and barrel while tightening the barrel into the receiver.
It won't matter in an un-bedded chassis, but if the lug and receiver are epoxy bedded, it will matter.