The M16 was six inches shorter than the M14, but it still wasn’t short enough. At least it wasn’t short enough for Vietnam. The dense jungles pressed in on you from all directions. It dominated the field. For the special operation snooping and sneaking the rifle was a bit too much. The troops demanded a shorter rifle, one easier to use inside of the dense terrain, especially when suppressors were being fielded. They received a weapon formally known as the Colt 605, a unique carbine that would eventually enter modern rifle parlance as the Dissipator.
Not Technically a Dissipator
We’ll get into the history of the name DIssipator a bit later. Technically it’s a brand name, and the original Colt 605 was never called a dissipator. It was a name slapped on the rifle retroactively and would become the name applied to all of these unique carbines. The Colt 605 more or less laid the groundwork for what would become the Dissipator.
Colt chopped the M16’s 20-inch barrel to 15 inches, and that’s about it. They threaded the barrel and added a muzzle device, but not much more. They kept the FSB, the rifle-length gas system, the M16 handguard, and the M16 stock. Trimming a little length off the front of the gun was enough to make it fairly short and light.
A modern M4 carbine features a 14.5-inch barrel, so the difference in practical length is quite small. We can start seeing the elements of what would become the CAR-15 carbines and later the M4 series through the Colt 605. The 605 was the original carbine length AR.
The 605 went to Vietnam and served with special operations troops, but it didn’t last super long. The gun had reliability issues. Trimming the barrel to 15 inches reduced dwell time significantly. Dwell time is the amount of time the bullet stays in the barrel past the gas block. If you look at Colt 605 photos, it’s clear they had next to zero.
This caused reliability issues, and the fix was to add a suppressor, which increased back pressure. The 605s were pulled from service. Colt would go on to release carbines like the Model 607.
Benefits of the Dissipator Design
The first was the fact it was shorter than the M16. Shorter rifles are easy to maneuver with, and in dense jungles, you don’t have much room to maneuver. That’s true today, as well as most military forces have switched to carbine-length rifles. They are easy to use indoors, inside and outside of vehicles, and of course, in the rice paddies.
Compared to other carbine designs, they do offer a distinct set of benefits. First, the rifle-length gas system provides a much smoother recoil impulse and less violent reaction. A longer gas system results in a just a much smoother overall experience.
With iron sights, the guns have a longer sight radius, which makes accurate shooting easier. A longer sight radius doesn’t matter a whole lot in the world of optics, but it deserves mention.
You can also use a longer handguard with a front sight base. A longer handguard is better for ergonomics and allows for more accessory mounting. However, in a day and age of low-profile M-LOK handguards and low-profile gas blocks, that’s not a big deal either.
What about the reliability issues the 605 had? The commercial market found a way to clear that up. It turns out that making the gas port bigger was the way to handle that. This helped clear up the reliability issues and was the same way the Mk18 works so well.
The Commercial Dissipator
The Colt 605 was never called Dissipator by Colt. That name came from Bushmaster, who produced a very 605-like rifle. It features a 16-inch barrel to avoid the NFA, but they did use a carbine-length gas system rather than open the port. The Dissipator namesake came from the longer handguards.
These handguards were apparently reinforced with metal inserts. These inserts and handguards were said to Dissipate heat. Thus, the gun became known as the Dissipator. This catchy name stuck, and now anytime we have an FSB pushed to the front of a barrel, it’s referred to as a Dissipator.
Brownells’ Retro line included a Colt 605 clone. I, unfortunately, missed my chance at acquiring one of these guns, and Brownells has mostly killed their retro line.
To this day, several companies produce Dissipator designs. Palmetto State Armory makes a neat one with a MOE handguard, but it’s got a mid-length gas system. It’s also quite affordable and well-suited if you want an iron-sighted carbine.
Windham Weaponry produces what they call the Dissipator M4, which also has a false gas block and shorter gas system. It comes with a carry handle and FSB, as well as the lower-priced M4 furniture.
Del-Ton actually makes the best option, in my opinion. The Del-Ton Dissipator uses a rifle-length gas system. Not only do you get the longer sight radius, but you also get a smooth recoiling system combined with a shorter barrel. It’s the only rifle-length gas system Dissipators I know that’s on the market.
The Appeal
The appeal to a Dissy these days is the something different factor. Carbines are boring, right? Everyone has one of those. Twenty-inch rifles are cool but fairly large. The Dissipator, though, that’s different. It’s compact but doesn’t look, feel or handle like any carbine. A rifle-length gas system makes it a much smoother shooter than a standard carbine., It’s somewhat sad only Del-Ton produces a Dissy kit. I would love to see other takes on the design.
With that said, it’s likely a small market for weirdos like me who like odd things and still enjoy shooting with iron sights. Even if the concept isn’t for you, the Colt 605 is a stepping stone to the M4, which is often considered the pinnacle of Eugene Stoner’s rifle design. It’s the most popular among military forces, and it’s led to many a dead bad guy.
What do you think about the Dissipator rifle design? Let us know down below, and I’m going to add a Del-Ton Dissipator to my shopping cart.
