AR15 and Ruger .22 Mk II nomenclature question

[Continental Op]

The AR15's upper receiver is analogous to the Ruger .22 Mk II's receiver in that it carries the barrel and bolt. The AR15's lower receiver is analogous to the Mk II's frame in that it carries the magazine well and fire control parts.

Can anyone explain why the Mk II's receiver is the serial numbered 'firearm' instead of the frame the way it is the AR15's lower receiver that is serial numbered?

Thanks for your help on this puzzler.

 

[rbrbrb6]

I believe it is simply a matter of where the manufacturer decides to serial number the gun.

 

[flundertaker]

the way the AR is designed with the lower being the firearm is superior. You can get 1 "gun" and have limitless variations due to the removable upper receiver. Its especially nice if you have a NFA stamp. The Ruger Mark series is dumb in its design (although I am lusing after a Mark II Government Target model) with the barrel, essentially, being the firearm.

 

[Beemerguy53]

the way the AR is designed with the lower being the firearm is superior. You can get 1 "gun" and have limitless variations due to the removable upper receiver. Its especially nice if you have a NFA stamp. The Ruger Mark series is dumb in its design (although I am lusing after a Mark II Government Target model) with the barrel, essentially, being the firearm.

I've had a Ruger MK678 Government Model Mark II for many years...it's terrific! Well-balanced and accurate, easy to shoot well. It's a pain in the neck to take down for cleaning, but I can live with that...