4 Retro-Inspired AR Rifle Builds You Can Build, Too

I had last summer off and I did a frenzy of AR building. Going back to work in the fall slowed me down a bit, but I still managed to get a few projects in. All of these builds were retro themed, and most were SBR’s. Just for the heck of it, let’s look at them from shortest to longest.

The N-23A1

The first build I did was based on the Recoil N-23 concept. The N-23, or Never Was (W being the 23rd letter of the alphabet), was a “what if” concept. It was based on the idea of imagining that the military had made a PDW during the Vietnam War and used features from some of the prototype M16 carbines and survival rifles from the era.

The N-23 was a 7.5 inch 5.56 with a slick side upper, short buffer tube, chopped CAR stock, and short CAR style handguards. It’s a slick build and probably quite the flamethrower. My local NFA shop, CDS Arms, had one they were working on and I determined that I really needed one, too.

I decided to build mine in .300 Blackout, figuring that it actually was much better suited to the short barrel than the 5.56 is. Since I was already deviating from the original concept I rummaged around my parts bin to see what I already had on hand that I could use. For a base, I had a Palmetto State Armory lower that was already SBR’d that I could use.

It was a typical modern A2 profile with black anodizing so I wasn’t going to get too hung-up on being Vietnam clone-correct, especially when I was basing this on a gun that never was. Since I was using a newer lower I found a C7 upper in my stash that I figured would work perfectly too.

I used a set of Luth AR A1 sights on the upper, and a teardrop forward assist and ejection port door assembly from JSE Surplus. I also had a bolt carrier and GI spec charging handle lying around from other projects.

For the barrel I went to Ballistic Advantage. I asked CDS Arms, for recommendations and that was who they suggested. BA was the only source we knew of where you could readily get a .300 barrel with a GI Front Sight Base.

When you order a barrel from BA you have the option of adding an FSB and either a round or triangular handguard cap. Eight inches was the shortest .300 barrel they had so I went with that length and the FSB and round handguard cap. I ordered the barrel through CDS, and grabbed a pistol-length gas tube from them while I was at it. The barrel came quickly and had the barrel nut, Delta ring and spring installed. I added an A2 flash-hider that I picked up from JSE Surplus.

For a short buffer tube I ordered the LWRC PDW assembly with stock from Midway USA. It’s a good setup, but if I was doing it over again I’d get the Mini MilSpec buffer tube assembly from KAK Industry. I didn’t really need the stock from the LWRC kit and ended up using it on another project later. With the KAK setup I could order just the tube, spring and buffer and add the stock I wanted. The KAK setup is a lot cheaper too.

Since the LWRC PDW buffer (and KAK Mini Milspec) is shorter than a regular carbine buffer you need a shorter stock to collapse all the way down to the receiver end plate. The LWRC one does, but it was more modern than I wanted, even though I wasn’t going totally Vietnam era with my build. KAK does offer a chopped M4 stock, but I wanted a CAR stock like the N-23 build. I ended up ordering mine from Harrington & Richardson and cutting the stock tube shorter with a hacksaw and then cleaning up the edges. That’s what they did for the Recoil build too.

Handguards were trickier. On the Recoil build they cut down a set of CAR handguards and epoxied it back together at pistol-length. I was a little skeptical of my ability to do that and have it look decent, but luckily I found a 3d .stl file that had just dropped right when I needed it.

AR180 Parts offers 3D-printed handguards for $50 a set if you need them and don’t own a printer. I’m still fighting with my 3D printer, but luckily have a buddy who’s better at it than I am. He ran off a set for me out of ASA polymer filament which should be a little tougher and more heat resistant than basic PLA or PLA+.

The print-yourself handguards don’t come with a provision for a heat shield so I added reflective heat shield tape on the inside to help out. That’s probably not as good as an aluminum heat shield, but it’s better than nothing.

The printed finish was matte black and you could see the print lines if you look closely, so I added a couple coats of glossy black engine paint and a clear coat to mine. That did a decent job of approximating the early shiny CAR handguards.

The last thing I needed was a grip. Recoil used an A1 grip, which would have been fine, but I dipped into early M16 history myself for my grip. Some of the early carbines and survival rifle prototypes just used chopped-down, shorter A1 grips and decided to go that route.

I didn’t have a spare A1 grip lying around, but I had a plethora of unused A2 grips. I figured I’d practice on one of those. I ground the finger nub off on my belt sander and cut the grip down even with a 20 round magazine in the mag well. I intended to replicate the grip with an A1 grip if it worked out, but honestly, I didn’t end up minding the modded A2 grip at all so I left it on.

With the gun complete, I just needed accessories. I decided to add a GI universal cargo sling connected with paracord, which has been popular on the retro build forums for XM177 builds lately. I didn’t want a modern magazine either but I found that my Brownells aluminum 20-round mags fed .300 Blackout just fine and looked perfect in the build. They don’t make the 20-round mags any more, which is a shame.

The end result is a .30 caliber AR that’s just 22.5 inches in overall length with the stock closed. Weight is 5.07 pounds with the sling installed. I could have saved a little more using a slick side upper but I think it’s fine how it is.

The final gun is super compact, the 300 Blackout should work much better out of the 8-inch barrel than a 7.5 inch 5.56, and it has a really neat vibe for another gun that never was. Since I deviated from the original concept in both caliber and by adding an upper with a forward assist I’ve dubbed this the N-23A1, and it’s become my favorite build to date.

The H&R 635

My next build actually started at SHOT Show 2023 when I saw H&R’s prototype 635 9mm pistol build with CAR style brace. The 635 was a 9mm subgun based on the M16 that Colt made starting in the early 1980’s. They’ve seen a lot of military and law enforcement use over the years.

The 635 SMG has a 10.5 inch barrel and is chambered in 9x19mm. It’s a blowback system and uses a slick-side carry handle upper with a special gas deflector block and a short ejection port door added.

Being that they were blowback guns, no gas tube was needed and the uppers didn’t have a hole for them. The 635 had a 50m/100m rear sight with a bigger aperture than an M16A1 rifle peep sight. Early examples used CAR 6-hole handguards, a CAR stock and A1 grips. Later versions saw A2 grips and M4 buttstocks used.

The Colt 635 used a magazine based upon the Uzi mag pattern with a notch cut to accommodate the M16 style magazine release and a mag well adapter pinned in place to take the subgun mags. The 635’s were always neat guns and a buddy of mine had a semi-Colt version with a 16-inch barrel years back. It was nice, but the long barrel killed the subgun vibe. Colt’s more recent models still used a 16-inch barrel and have used a flat top M4 style upper and didn’t have the 80’s and 90’s look. When I saw the H&R version with its carry handle and 10.5 inch barrel though, it was love at first sight.

Not long after SHOT, H&R dropped complete lowers and I grabbed one right away. Unfortunately uppers proved to be a ways down the line. Between the ATF putting a damper on the original plans of offering a pistol version with a CAR style brace, and general manufacturing backlogs, uppers wouldn’t hit until mid fall.

I submitted my 635 lower for a tax stamp as soon as I got it because I knew I wanted it in a subgun configuration and at the time the brace issue was being litigated in court and there was no injunction on the horizon. ATF does what ATF does and it took 57 days for my Form 1 to be approved, but I wanted to be ready while I waited.

When I got my lower half you could get any color you wanted…as long as it was black. I picked up a complete lower half with CAR stock and repro A1 grip. The guns are engraved with the H&R lion in a circle, right where the rearing horse logo would be on a Colt. Below that it’s marked with a large “SMG” like the originals. Then MOD: 635 and CAL: 9mm NATO then the serial number which starts in SMG. Whereas the Colt’s used a standard M16  or AR-15 lower with a pinned magazine adapter, the H&R’s use lowers with dedicated 9mm mag wells cut for the Colt pattern magazines.

Since H&R didn’t have a timeline for uppers, I started piecing together my own. I picked up a Rock River Arms 10.5 inch barrel with FSB directly from Rock River along with an A2 9mm flash hider. I grabbed a Stern Defense bolt carrier from Brownells along with a GI spec charging handle. I got a set of old 6-hole handguards in a trade, as well as a GI surplus fat A2 grip.

Now, you can use any slick-slide upper and it doesn’t matter if it has a gas tube hole or not. I decided to go more traditional though and picked up an upper receiver from Mayhem Machine Tool called The Nuke, named after the Colt 633 subguns used by the Department of Energy for nuclear plant security. Like the originals, it lacks the gas tube hole. It’s a well-made upper and perfect for clone builds since the only markings are on the receiver lugs where you don’t see them when the gun is assembled.

I added a sight kit from JSE Surplus as well as a correct port door. The 635’s used a shorter ejection port cover that was cut off straight from a full-sized door. Newer 9mm port doors have rounded edges. They work; they just don’t look right depending on your particular  level of OCD. I initially got my port door kit from Brownells and while the pic showed the correct style door it came with the newer door. I believe they’ve since corrected the pics.

I reached out to JSE when I was ordering other parts and they actually pulled one from stock and took a pic of it to send me before I ordered to be sure it was the right style. You can’t argue with customer service like that.

Once my tax stamp finally was approved, assembly was straightforward. Not having to line up a gas tube with the barrel nut made things even simpler than usual. The only thing I ran into was that with the gas deflector block installed on the upper, it wouldn’t fit my old Wheeler clamshell vice block and it wouldn’t work with my Otis reaction rod since the 9mm barrel doesn’t have locking lug cuts. I improvised blocks to hold the upper in place when I torqued the barrel on but later got a Wheeler Delta Series block for situations like this.

The Rock River barrel didn’t have a front sling swivel installed but I had one in my parts box. I picked up a correct rivet from JSE when I ordered the port door along with a set of A1 sights. I looked for a correct 50m rear sight but was never able to find one. I eventually swapped the A1 rear peep out for an A2 peep with the bigger aperture, which is closer to the 50m 9mm aperture. I found that it’s a common substitution since the 50m rear sight seems to be unobtanium at the moment.

I picked up three 20-round Duramags and two 32-round Duramags, and my wife got me three H&R 32-round mags for Christmas. I haven’t add a sling to mine yet. I was considering a long GI silent sling that can be used patrol style, but haven’t decided yet.

The HK MP-5 may have ruled the 80’s and 90’s as the law enforcement and military subgun of choice, but the Colt 635 still has a solid following. The H&R 635 makes for a viable clone to scratch that 90’s subgun itch, albeit in semi-auto SBR form. It’s a handy package with all of the familiar AR/M16 controls and is incredibly swift shooting in 9mm.

The Israeli IDF Menusar

My other build was a clone of the Israeli Menusar, also sometimes called the Mekut’zar, carbine. I’ve always liked the looks of these handy M16 carbines and started gathering parts in the early fall. I had a good library of research pics saved up to work from and with the terrorist attack on Israel in the fall of 2023, they’ve been popping up in a lot of news photos again.

Back in the early 1970’s Israel received tens of thousands of M16A1’s as aid from the United States. They later bought more on their own. These were initially traditional fixed-stock, 20 inch barrel rifles, but as time went on and Israel needed a shorter, handier platform they began to convert those M16’s by swapping out the fixed stocks with a carbine buffer tube and CAR stock, and by shortening the barrels. They chopped the barrels down just behind the gas port, drilled a new port and shifted the front sight base back.

The new barrels were slightly under 13 inches with the original A1 flash hider installed. CAR handguards were then added. The new carbines were light, particularly with the cut-down A1 pencil barrel, short and handy. They were also a fairly cheap conversion.

While the Menusars have long been replaced in active service with Tavor bullpups, and newer M4 carbines, you still see a lot of them showing up in the hands of reservists. Some show impressive amounts of finish wear but they’re still soldiering along. While the CAR stocks and A1 grip were the most common initial configuration you’ll see some with M4 waffle stocks, A2 grips and A1 and A2 style Lone Star grips as well. Many still sport iron sights, but others will have a Meprolight optic on a dogleg mount.

When I first started my clone build I was thinking I’d either need to find a Colt lower or just accept that my lower wouldn’t be clone-correct. Thanks to some great pics in the Reddit Retro AR group, and some info from guys in Israel, I found out that H&R and GM Hydramatic guns were part of that initial aid package from the US and were turned into Menusars, so they’d also be clone correct.

With that in mind I picked up a current production H&R M16A1 lower half to use for my build and immediately submitted a Form 1 to SBR it. Once again, while guys were getting one week or less turnarounds on their e-file Form 1’s I had to wait 80 days for mine. Thanks, ATF.

In the mean time, I picked up an A1 upper from AR15Discounts, a Brownells 12.7 inch pencil barrel with FSB, and A1 flash hider teardrop forward assist and Luth AR A1 rear sight kit from JSE Surplus. I got a phosphate BCG and a basic charging handle from Palmetto State Armory. I had a set of old 6-hole handguards that I picked up in a trade and swapped out the repro A1 grip that came with my lower for a Clone Star grip from Onyx Arms. I don’t see Onyx showing these grips any more, but rumor has it that B5 Systems will be doing a version soon.

I ordered a TDI IDF sling from Atlantic Firearms and an IDF accessory kit from Zahal in Israel. I also ordered a mag carrier like the IDF reservists use when off duty, but they’ve been backordered so I’m still waiting on that.

Once my stamp came in, I finished the assembly of my Menusar and have to say it’s one of the handier AR’s I’ve used. I can see why it’s been a popular service rifle for working in urban areas and around vehicles and armor. The 12.7-inch barrel is enough to give the velocity it needs to be effective, too. You aren’t getting the velocities you would from a the 20-inch barrel that the Menusars started with, but it’s a good jump over 10.5 inches and still a bit handier than a 14.5-inch M4.

The Fallout New Vegas Service Rifle

The other build I did was one I started last summer. It was my take of the Service Rifle from the Fallout New Vegas video game. Initially I had built a Dissipator setup with a C7 upper and brown plastic Brownells A1 retro stocks. It had the general feel of the game gun but was missing a lot of details.

I ended up picking up a Service Rifle-marked lower from Bad Attitude Department to replace my basic PSA lower, swapped out to a more correct 20 inch pencil barrel from Brownells, added a chrome BCG and polished trigger and, most importantly, a set of Battle Worn black walnut stocks from American Icon. I covered the stocks HERE and talked a little bit about the build there already so I won’t dive in too deep here.

There may be a few quibbles on the details but, being that I was cloning a gun that doesn’t actually exist outside a video game anyway, I think this one comes pretty darn close. It definitely captures the feel of the game gun and makes for a really slick retro gun that also never was, but maybe should have been, just like the N23A1 that we started this article with.

Spring is likely going to have another crop of builds, but that will be another story for another time.