If you’re a fan of retro AR’s and M16’s, you know that some of the most iconic ones are the XM177 series models that came out of the Vietnam War. In those heady, early days of the M16 a number of variations were made in an effort to make a more compact version of the M16 service rifle.
The XM177 series, with its big sound moderator, is one that most military buffs and gun enthusiasts think of when you think Vietnam. I’m no different, and it was inevitable that I eventually had to do my own build.
A Quick XM177 History
The XM177 and XM177E1 both came about in late 1966. They had 10-inch barrels and a 4.5-inch sound moderator. The XM177 was the Air Force issue variant and lacked a forward assist. The XM177E1 was the Army version and was equipped with a tear drop pattern forward assist.
These early guns had some reliability issues with the short barrel and gas system, which lead to the introduction of the XM177E2. The XM177E2 model developed in 1967. It used an 11.5 inch barrel, which provided better reliability and accuracy, and again a 4.5 inch moderator. Later versions also had the addition of a grenade ring behind the moderator.
My XM177E2 Build
Although I like the look of the shorter barrel on the XM177/E1 version, I opted to do an E2 build just to avoid any possible reliability issues. I thinks that’s much less of an issue today since teh AR/M16 platform has had a chance to evolve over the intervening decades, but I figured I’d play it safe. I researched what parts I’d need at Retro Black Rifles. It’s a great source for getting the details on an M16 based clone build.
To start my build I picked up a stripped XM1777E2 lower from Harrington and Richardson. H&R never made any original XM177’s, but the current H&R’s are accurate reproductions. They have the correct A1 profile lowers, US property markings, and XM177E2 markings. I added a gray 2 position buffer tube from Linemount, like the originals. I initially used a plastic CAR stock, but I swapped that out for a rubber covered aluminum one from DoubleStar Arms, which is the style the original guns would have had. I used a B. King Firearms lower parts kit although I sprayed the trigger guard gray with Norrell’s Moly resin, and swapped out some visible parts with older, gray ones and an non tick marked safety.
I had a gray anodized A1 upper that I had picked up in a trade available for the build. I added am A1 rear sight kit, ejection port cover, and a teardrop forward assist from Luth AR. I picked up an 11.5 inch barrel from Brownells as well as their flash hider and grenade ring. I got the CAR handguards from H&R. They’re as close to the original shiny Colt’s as you can get with a current reproduction.
As mentioned, the original XM177 actually used a sound moderator. It didn’t actually moderate sound that well, but it’s enough that the ATF considers it a suppressor, so most folks doing clones use a flash hider like the Brownells one. It has the right look, without being classified as a suppressor. The barrel I used is a 1-7 twist, not a 1-12 like the originals, but it was the correct profile and what was available at the time of the build. It also gives me a bit more flexibility with ammo. It came with a flat slip ring, but for the XM177E2 the Delta ring was more correct so I swapped that out. To round out the upper I used a chrome Microbest bolt carrier group from AR15 Discounts. Although in hindsight, a phosphate BCG would be more correct, so I may swap that out at some point.
For the grip, I found an original H&R bakelite grip from Numrich Arms. Being that the overall length with an unpinned moderator is under 16 inches, I e-filed a Form 1 to SBR the build. With the blissfully short turn around times right now I only waited about a week for approval. Yeah, the NFA sucks, but if we have to deal with it for now, at least the wait times are down.
To finish things off I added a US general purpose cargo strap for a sling and paired it up with some old GI 20 round mags. I have a small stash of mags that my brother got from a friend of our dad’s that he brought home with him from Vietnam. Can’t get more original than that!
XM177E2 Handling
I was pretty pleased with the finished product. Some of my clones are more correct than others. But this one is pretty darn close. I can see why the XM177’s were popular with users. It’s a very tight, compact package and points and handles easily. At a weight of only 6 pounds, it’s also easy to carry. Operation is the same as any other M16 or AR so nothing new there.
I was pleased to find that my XM177E2 worked right out of the gate with no tweaks needed. I didn’t even need to adjust the sights. That was pure luck, but I’ll take it. I ran a mix of 55gr and 62gr loads through it over the summer with no issues. I didn’t bench rest it but it was plenty good for shooting at milk jugs and my Caldwell reactive targets.
I also used the XM177E2 with the CMMG .22 conversion kit that I picked up over the summer. It’s an easy conversion just by swapping out the BCG and using the provided .22 LR mags. It made for cheap, fun plinking and I didn’t have any issues with it either.
Functional History
The XM177E2 is definitely a historical piece, coming out of the Vietnam War as it did. With that said, they continued on in US service at least into the 1980’s and I’ve seen some comments online indicating some may have been around in Air Force and Guard units even into the early 1990’s. Even today, it’s still a light, handy carbine for the farm or camp, and it’s a lot of fun to shoot. If you like your AR’s with a bit of nostalgia, the XM177E2 is a good option to look at. You can build your own like I did, or buy a complete E1 or E2 model from Harrington & Richardson.
Close but no cigar.
Hello shootingnewsweekly.com admin, Thanks for the well-structured and well-presented post!