My nephew LOVES his Moose ... but then he also loves LOUD music and RAP. So far, he has turned me down twice on my offer to fit him up with a spare longer barrel.
Go figger ...
Personally, I can't see the tactical roll of a .223 cartridge in a barrel under 16". When I chronoed 55 Gr Win NATO spec BALL I got 3100 from the 20", and 2200 from the shorty. In the AR platform, I'm moving over to .300 Whisper. Better ballistics all around [ especially from the shorties ]... without the five gallon pail of fire and noise hanging off the muzzle with each shot.
[;{)
LAZ