Thompson chose to use Trijicon RCO he uses on his standard M4 carbine.

Thompson chose to use Trijicon RCO he uses on his standard M4 carbine.

Shooting .22 handguns or rifles has always ranked high among fun shooting—plinking, if you will. Small game hunters have continued to use .22 arms to good effect, too.

But cost isn’t the only factor that has made .22-caliber copies of service pistols or rifles appealing. Many law enforcement agencies do much of their training on indoor pistol ranges, which makes carbine training difficult. With .22-caliber versions of tactical carbines, though, it is possible to do a substantial amount of training indoors and at a lower price. There still needs to be outdoor training or qualification with the duty weapon and full power loads, but a lot of muscle memory, reaction, and scenario training may be carried out with the .22-caliber versions of duty weapons—if they duplicate feel and functioning closely enough.

As the M4 carbine has become more popular for law enforcement, the usefulness of .22 Long Rifle versions has become more apparent. A fairly common solution for armorers or other shooters who use an AR-15 a lot has been to acquire a conversion unit which may be used with the standard service weapon. Another option has recently become available as well, in copies of the M4 carbine dedicated for the .22 Long Rifle.

Colt/Umarex with adjustable iron sights supplied with it. Magazine has thumb button for easy loading and displays the rounds.

Colt/Umarex with adjustable iron sights supplied with it. Magazine has thumb button for easy loading and displays the rounds.

One of these that has garnered quite a bit of interest is the Colt/Umarex M4. This carbine looks like an M4 and retains many, but not all, of the operating characteristics. The version I tested— the M4 Ops—has a 16.2-inch barrel and adjustable telescoping buttstock. With stock extended, overall length is 34.4 inches. The carbine incorporates an A4- type flat-top receiver, A2 flash hider, and A2 pistol grip. The M4 Ops tested has a rear BUIS (backup iron sight) and a free-floating aluminum Picatinny rail handguard. Weight of the carbine is around six pounds—very close to a standard M4. The difference in weight is obviously because a full 30-round magazine of .22 Long Rifle rounds will be lighter than a full 30-round magazine of 5.56mm NATO.

Let’s talk first about the features that make the Colt/Umarex a useful training tool for users of the M4. The charging handle and stock work in the same manner. Because it has a top rail, the shooter may use the optical sight of his choice.

I want to editorialize on two issues here, though. The front sight is fixed, which means that some popular optical sights will be difficult to mount. I would much rather have seen a detachable or folding front sight.

My other point relates primarily to those who plan to use the Colt/Umarex for training purposes. There will be a tendency for some to choose an inexpensive optical sight since this is a .22 carbine. If using it for training, this is a mistake. The same sight used on one’s M4 should be used on the Colt/Umarex.

In my case, I use the USMC Trijicon RCO (Rifle Combat Optic) on my primary LE M4, so that is what I mounted on the Colt/Umarex. As a result, any training I do reinforces the use of that reticle quickly. I know that this optic costs quite a bit more than the Umarex carbine itself, but for training purposes, any other optic would be a compromise. For those who purchase the Colt/Umarex as a fun rifle or a rifle for the kids to shoot, then choice of optical sight can be determined more by budget.

One-hundred yard group fired during zeroing process is fairly typical of Colt/ Umarex’s accuracy.

One-hundred yard group fired during zeroing process is fairly typical of Colt/ Umarex’s accuracy.

There are features of the Colt/Umarex M4 which I feel make it less useful for training purposes. The two I find most annoying relate to the safety and the bolt release. The safety requires full 180-degree movement to release or apply it, as opposed to the 90-degree movement on semiautomatic AR-15s. This completely messed me up in testing, as I would raise the rifle from the low ready, pull the trigger and get no result (since I had only pushed the safety halfway), then go into a malfunction drill.

It is also impossible to fully disengage or engage the safety without shifting the hand on the pistol grip. The bolt release is a dummy and will not release the bolt, so anyone who normally uses the release will stand there pressing a lever that does nothing. The charging handle must be used to release the bolt. The dust cover is also cosmetic and may not be pushed into place.

Although it does not affect training, the takedown procedure for the Colt/ Umarex creates some issues. On the version I received, the manual does not have all the necessary information for disassembly. This was rectified on later manuals, and users can also go to the website for a video on disassembly and cleaning.

The procedure requires that the flash hider be loosened two turns before driving the cross pin out with a punch and hammer. Unlike standard M4s, the takedown pin may not just be pushed out and it is not captive, so care must be taken when driving it out not to lose it. Once the pin is driven out, the upper rotates as on a standard M4. But be careful, as there are two small parts that will fall out and can easily get lost. One is the fake bolt release.

For cleaning purposes, there is not a removable bolt. The actual operating system is a combo chamber/bolt unit that is fixed in the upper. Cleaning of the chamber must be carried out using a pull-through. Other parts may be cleaned and oiled with the upper open as well.

The feature that has caused me the most problems is a hex screw on the rear of the chamber/bolt assembly designed to regulate bolt speed. The instructions state that it is to be used to regulate for standard velocity or high-speed ammo. With standard velocity ammunition, I was having a few malfunctions, so I tried to adjust bolt speed as per the manual.

Instead, I made it worse and was not smart enough to count how many turns I had taken on the hex screw to return to the original setting. There are also no witness marks to assist returning to any setting. I felt very stupid until I was at a seminar with a group of other gun writers and found that two others testing the Colt/Umarex were in the same situation.

Accuracy was fairly good with the Colt/Umarex. Two inches at 100 yards is usually considered rather good for most .22 rifles, and I was getting some groups in the two- to three-inch range. At 50 yards, where I did a lot of shooting, I was generally in the 1.5- to 2-inch range. I found the accuracy acceptable.

Colt/Umarex with upper rotated open— note dust cover is merely cosmetic. Bolt and chamber are self-contained unit in the upper.

Colt/Umarex with upper rotated open— note dust cover is merely cosmetic. Bolt and chamber are self-contained unit in the upper.

Reliability was not 100% even before I adjusted the bolt speed and was worse afterward. I am now using high-speed ammo and adjusting the hex screw one turn at a time until I find the most reliable setting. Unfortunately, since the carbine has to be disassembled to adjust the bolt speed, I am reluctant to do much adjusting at the range because I may lose one or both of the small parts that fall out.

Overall, I’m giving the Colt/Umarex M4 .22 a mixed review. On looks I give it good marks, as it does look very much like an M4. For many, the Colt logo on the side will mean quite a bit as well. The feel of the Umarex is close to that of an M4, and the flat-top rail allows me to mount my RCO in the same position as on my Colt LE M4. Accuracy is good enough for shooting out to 200 yards.

The trigger pull is a bit heavy, which impacts on accuracy to at least some extent. I dislike the fact that the safety and bolt release do not allow me to operate them in the same manner as a standard M4. I also would prefer that I could just push the takedown pin out and open the upper receiver rather than have to loosen the flash hider and use a hammer and punch. I don’t like the idea that I have to carry special tools to disassemble the carbine in the field and may lose small parts if I do.

Since .22-caliber weapons usually get quite dirty, the need to use a pullthrough to clean the carbine would not be my choice, but with care you should be able to get the chamber and bore clean. The problem with the hex screw that adjusts the bolt speed is to some extent my fault, but the lack of very clear instructions about when to adjust the screw and by how much will lead many to make the same mistake I did.

For those of you who are considering purchasing a Colt/Umarex M4 .22, I offer the following advice:

  • Go to the Umarex website and watch the demonstration of how to disassemble and clean the carbine.
  • When disassembling the carbine, be aware of the small parts which may get lost.
  • Be very careful about adjusting the bolt speed control screw.

Prices vary a bit on the Umarex M4, but seem to run about $600. A .22 M4 should make a great contemporary rifle for the young shooter who wants a military-style rifle. It also offers possibilities for training as I’ve discussed above.

Umarex USA
Dept. S.W.A.T.
6007 South 28th St.
Fort Smith, AR 72908
(479) 646-4210

Trijicon, Inc.
Dept. S.W.A.T.
49385 Shafer Ave.
Wixom, MI 48393-0059
(800) 338-0563

About Author

Leroy Thompson

Leroy Thompson has trained hostage rescue, close protection, counterinsurgency, and anti-terrorist units in various parts of the world. Prior the Operation Desert Shield he trained U.S. Army protective teams and hostage rescue units. He is the author of over 50 books on weapons and tactics and somewhere between 2,500 and 3,000 magazine articles.

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