The clone wars continue. I’m slowly but surely working my way through cloning all of the early M16 and M16A1 variations I can reasonably do. This one took a while to come together and get right, but I’m finally calling it finished.
The Colt 605 was the first attempt by Colt to make a carbine out of the M16 platform. They did it in the simplest manner possible: they just chopped the barrel off right in front of the front sight base. That knocked the barrel down from 20 inches to 15 inches.
The 605, later referred to as the Dissipator, was only made in small numbers as it didn’t prove to be reliable. Still, it has a distinctive look that Vietnam War and M16 buffs have been enamored with ever since. I’ve wanted one for years and decided it was time to build one.
The Saga Begins With Mayhem
Mayhem Machine Tool makes high quality uppers for classic AR builds. In particular they make hard to find one, like the upper I used on my M16K and Colt 635 clones. They’re the only ones I’m aware of that make the correct style upper for early Colt 605’s.
Colt initially used Model 603 upper forgings, but milled off the area where the forward assist would be installed. That left a distinctive hump in the upper receiver, just behind the ejection port. Later they just used slick side uppers. Either is correct for a 605 build, but the Mayhem Machine 603 style, which they call the “Secret Weapon,” is the most unique.
I decided if I was going to make a 605, this was the upper I wanted to use. I got my upper in the raw since I wanted to finish it with Norrell’s Moly Resin using their “Grayish-Black Colt Flat” color. These are currently showing as out of stock on the Mayhem Machine website, but they make batches of them periodically.
I then picked up an H&R Model 604 partial fence lower half. This was complete with the early Type D style buttstock and gray finish. H&R’s 604 lower is the correct configuration for a 605, but obviously has H&R markings rather than Colt, and is stamped simply M16.
I swapped out the grip with an original one that I had picked up from Numrich back when you could could by the grubby ones for under $7 a pop and clean them up yourself. I got a set of really nice condition original handguards off of a buddy in the Spring and set those aside while I waited on a barrel. I also had an original seatbelt sling that I picked up when I visited the CMP North store last Fall.
After painting the upper with Moly Resin, I assembled it with a Luth AR A1 rear sight kit and Brownells ejection port door. I also picked up a slick side chrome bolt carrier group and three prong flash hider from Luth AR. The barrel was the hardest part to source since correct profile Dissipator barrels aren’t super common. Brownells makes them, but they hadn’t been in stock in a while. When I got a restock notice in the late Spring I immediately ordered one.
Round One Build
With all of my parts in hand I finally got down to assembling my 605. The result was, well, okay. It was a neat a rifle. It was handy and it had the 605 vibe, but it wasn’t correct. Due to dumb NFA laws, the Brownells barrels are 16 inches, then you add the flash hider making the whole assembly a lot longer than a real 605 would have been. Plus the front sight base has a bayonet lug, which 605s didn’t.
Then there was the color mismatch. The Norrell’s gray was a good bit lighter than the H&R gray. Initially I justified it as reasonable since many military guns didn’t match up either. That’s true enough, but tell that to my chronic case of OCD.
I sat on the gun like that for a few months and while perfectly functional as it was, I wanted it to be better. I’d gone through the trouble of getting the right profile lower, the right upper, a slick side bolt, and some other odds and ends to have a decent 605. I was pushing for a clone, not just a “Dissipator-style” rifle.
After some reading and looking at other builds on Ar15.com’s retro forum, I decided to send my upper off to John Thomas at Retro Arms Works and have him make it right.
Round Two Build
John Thomas comes highly recommended by anyone who has used him. I’ve seen his name pop up a lot over the years in the retro forums, and guys always praised his work. He’s the go-to guy for this kind of thing. I reached out via email and got a prompt reply.
To make my 605 correct he would remove the bayonet lug and forge flash lines from the front sight base, and re-parkerize it. He also needed to cut the barrel back to 15 inches, crown, and thread it. Then he’d have to install the muzzle device and pin and weld it in place to bring it back to 16 inches to stay in NFA compliance.
John’s prices were reasonable for the work done, especially factoring in his knowledge of the retro guns and how they should look and be configured. He works super-fast, too. I had my upper back within two weeks including shipping time both ways.
When I got my barreled upper back, everything looked perfect. Folks weren’t exaggerating when they said John does amazing work. Not only was the work great, but he actually called me to point out some things he noticed on my upper, including the thin finish and some corrosion that had started because of it.
He gave me some great tips on cleaning it up and ways to improve on future builds. Super-nice guy, and I definitely appreciated the heads up and knowledge sharing. I’ve cranked a lot of AR’s together at this point but have no formal training (other than one time through the GLOCK armorer’s course, which doesn’t really help much here) so I’m definitely open to tips.
Between the quality of work and taking the time to help me out on my builds, I can see why everyone recommended Retro Arms Works so highly. I know that’ll be my go to the next time I have work that needs done.
The Final Build
With everything back in house and recoated, I put it all back together. Other than the couple of rough finish spots I mentioned, I think it came out darn nice.
It’s mostly repro parts, but there’s a smattering of original stuff in there as well. I even pulled out my old Colt and Adventure Line 20-round mags to go along with it.
This was another grail build for me. I’ve been fortunate to be able to knock a few of those off my list over the past couple of years thanks to the companies and small businesses that cater to the clone market, and folks like John Thomas at Retro Arms Works who can correct the rest of it. I know it’s still not 100% perfect, but it’s far closer than I expected to get when I started the process. I’m calling this one done. It’s time to move on to my next build.
Nice build Tim.