M-16 tribute accuracy

[LRRPF52]

I've been a big fan/student of the AR15 family since I was a kid in the 1970s. At that time, that was all there was that we ever saw, in addition to the Colt Commandos.

Along the way, I've learned about a whole assortment of variations in both production and prototypes that you don't normally see.

I've built several retro ARs as well, with a focus on purism externally, but performance internally.

Here are my Colt 727 and Colt 605 clones:



The 605 was the first carbine production model, made in very limited numbers. It was supposed to be an Infantry Leader's carbine, basically a rifle with a 15" barrel and everything else the same. Since it had 15" barrel + RLGS, they had reliability issues with them in cold weather. Extending the barrel even .75" seems to take care of the dwell time, but a lot of people open up their gas ports to over .100", whereas a normal rifle port is .0935".

I've been thinking about converting the 605 to 6.5 Grendel, and I have another 605B in pieces but not complete, using an 80% lower to get the markings and 4-way fire control group represented.

The US Navy had a lot of 602s and 604s, which were both slick side (no forward assist). The USAF specifically demanded that their M16s not have any forward assist, like the original production models, whereas the US Army insisted on a forward assist.




One thing that really sticks out with the early AR15 military rifles is how lightweight and handy they are. Once you start putting in heavy barrels, they become much more stout. Interestingly enough, the prototypes had rather large barrel diameters under the handguards, but were fluted, and then had very thin fore ends in front of the FSB.




The most popular retro clone build is the Colt 603 (M16A1), with forward assist, 20" pencil barrel, triangular handguards, one of the Type D or E buttstocks, a full fence lower receiver (but nit later A2), the original pistol grip, etc.