Actually the bayo lug extension was designed to be shorter than the barrel.
The MK1 military barrel was the only factory 21 inch barrel (improved choke) that remington ever made.
When people install them on non mk1 shorguns they tend to stick them on factory 20 inch barrels, which winds up with the bay nub hanging out too far.
The police 3 shot factory extension was essentially the 3 shot extension used in the bayo lug for the mk1 but modified with a little clamp instead of the big reinforced armature to take the bayo lug.
The 2 shot factory extension was modified from the 3 shot factory extension tooling so it kept the stepdown even though it doesn't really do anything.
I actually have some oriinal MK1 parts, two forend's, and the bayo lug extension... (if you ever want to get rid of yours I would LOVE to do up two matching MK1's) ..... I just ordered the corect era sage stock to duplicate the look from the classic photo.
On my MK1 clone's I use a factory 30 inch barrel and then cut it down to 21 inches to get the 'correct' look, even though it gives me a cylinder bore not an improved choke like I really should be running.
