AERO precision: Enhanced Series Upper Receivers – “Enhanced” really means enhanced.
 

Ease of Rail and Barrel Installation
Simply insert your barrel assembly into an Enhanced upper, tighten it using the provided barrel nut and wrench, slide your rail on and tighten the rail screws. Within minutes you have a modular, free-floated rail.


http://aeroprecisionusa.com/ap/enhan...kaArmoEALw_wcB

Not sure how long they have had this out but pretty darn slick. No more pain in the ass lining stuff up crank her down and done. :thumbsup:

https://www.youtube.com/watch?v=5ZN1qiyJYiM

Lewis Machine & Tool has had their LMT® patented Monolithic Rail Platform for some time. While its set up for a piston gun, barrel changes are easy as 2 cross bolts.