Umarex/Colt M4 .22 LR Carbine

The Black Rifle has a "not-so-little" Brother

Reviewed by Steve Clark for M1911.ORG

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Our Forum also has an area for the discussion of weapons which are not of the 1911 type. This section of the forum generates many different threads, as well as interesting discussions concerning these guns. To this end, this gun review will be the first in a series of articles about various weapons which our members and guests might find enjoyable.

The renowned firm of Carl Walther (in Germany) has entered into a licensing agreement with the New Colt Holding Corporation to produce a series of M16/M4 type rifles and carbines chambered for the .22 Long Rifle cartridges. Umarex U.S.A. Incorporated is the distributor and warranty/repair center for these newly manufactured guns.

Two photographs of the new Umarex/Colt M4 .22 LR Carbine showing the retractable buttstock extended to its full length.

The Rifle

The concept is simple. Produce a rifle/carbine that looks, feels, and functions as closely as feasible to the venerable Colt Model MT6400C. This is the civilian version of the Colt M4 battle rifle used not only by the U.S. military, but by several other countries in the world. But concept and reality are two different breeds of cat. Add unquestionable reliability and accuracy to the mix, and it’s easy to see why Colt turned to Carl Walther of Germany to come up with a viable, marketable weapon.

Umarex distributes several variations of the Colt M16/M4 rifle, but Justin Biddle of Umarex Inc. sent the M4 version to Downing’s Guns in Cleburne, TX. As it turns out, Todd Downing had purchased one of the first available M4s for his personal use, and he was pleasantly anticipating my reaction to seeing the gun for the first time. Neither he nor I was disappointed!

The rifle is packed in an extremely heavy-duty cardboard box, with “Colt” emblazoned on the top.

Inside the equally strong partitioned box is found the rifle, a cable lock, hex wrench for bolt adjustments, a wrench for compensator removal, various leaflets, and the owner’s manual. One thirty round magazine is also anchored in an immobile position within the package.

The Umarex/Colt M4, at 6 lbs. (2750g), is only about one pound less than the genuine article, but picking up and shouldering the weapon doesn’t reveal that difference. The heft is the same, as is the balance of the gun. In fact, the weight difference can be attributed to the blow-back functioning of this rim fire mechanism, as opposed to the gas-impingement system and locking bolt found on a typical M16/M4 rifle. From the back of the telescoping butt stock, to the end of the compensated/flash-hider equipped 16.2 inch (412mm) barrel, the rifle exhibits its Colt parentage.

Nowhere is this parentage more apparent than on the left side of the rifle. The magazine well sports the Colt logo and Rampant Colt, M4 Carbine, and caliber .22 LR designations.

The view in the preceding photograph also illustrates the stunning similarities between the Umarex/Colt and a weapon chambered for the traditional .223 Rem./5.56mm rifle. The removable carrying handle/rear sight is the A-3 type. This allows the addition of multiple after-market sights or optics on the flat top of the rifle. The spring-loaded ring holding the hand guards is also the same as used on a standard M16/M4 rifle. Thus, custom hand guards, or those manufactured with top, side, and/or bottom rails (for the mounting of all the paraphernalia that some M4 owners love to hang on their weapons) can be added to the rifle.

There is the left side mounted two position safety above the trigger, and the familiar take-down button located immediately aft and above that safety. It must be noted, however, that the bolt-catch/release button is non-functioning. While the bolt IS held open after the last round is fired from the magazine, the rifle has an internal bolt catch which must be released with the magazine removed, and the charging handle pulled back to release the bolt.

The three other pins located above the trigger are FALSE pins, and removal MUST NOT be attempted, as all that will be accomplished is the marring of the rifles exterior. This is also mentioned in the owner's manual, and tampering with these false pins will void the warranty.

Moving to the right side of the receiver of the rifle reveals the familiar controls found on the numerous M16/M4 type weapons on the market. The magazine release functions as intended, but the rest are mostly cosmetic in nature. The bolt assist (added to the M16 during the Vietnam War) moves, but is non-functioning. The dust cover (over the bolt) does not have the spring and plunger mechanism found on true M16/M4 rifles. While it will close (as illustrated in the preceding photograph), it is easily dislodged. The nature of the blow-back operated bolt makes the need for a dust cover overly redundant, therefore the inclusion of the part was for authenticity more than function. The cartridge/casing deflector (to the rear of the bolt opening) MIGHT occasionally prevent a .22 LR casing from coming toward the shooter, but again we see a cosmetic addition to allow the Umarex/Colt to more closely resemble the original rifle.

Please note that the use of the term “cosmetic” is probably deceiving. This weapon is intended to be an exact replica of the M4 battle carbine, but chambered for the very much milder .22 LR cartridge. Accoutrements which were added to the M16 over the years were done out of necessity or by recommendations from those using the rifle in combat. A bolt-assist is necessary on a battle rifle, so the inclusion of this part on the Umarex/Colt is for authenticity rather than function. I happen to like the fact that these things are a part of this weapon.

The front and rear sights are exactly the same as those used on the A-3 equipped M4s being used by soldiers, law enforcement personnel, and civilian shooters.

Side Note: It is important to point out the charging handle of the Umarex/Colt. This handle functions in exactly the same manner as those found on standard AR15s, M16s, and M4s. The only variation comes from the fact that the charging handle is not a part of the take-down system, but remains in the rifle during field stripping.)

The preceding photographs show the rear sight, fully adjustable for both windage and elevation. Only a minor amount of “fiddling” was required to dial the sights in for the various types of high velocity .22 Long Rifle cartridges used during the shooting evaluation. While the various knobs are fairly self-explanatory, the excellent owner’s manual gives a complete description of the methods necessary to sight-in the rifle.

Those who shoot standard M16/M4 rifles are aware of the fact that elevation must sometimes be “fine-tuned” by moving the front sight up or down. True to the original, I adjusted the front sight to allow for some long range shots. Once again, the owner’s manual gives good instructions on how to perform these sight adjustments.

In the mid-1970s I bought my first AR15 Colt rifle. Those days the gun was equipped with the standard solid butt stock. While never uncomfortable to shoot, there were many times that the rifle was a bit ungainly while walking in the woods. I also wished, on occasion, that I could shorten the “pull” slightly. The advent of the telescoping butt stock solved a myriad of problems in the military, and for me as well. The Umarex/Colt M4 .22 rim fire comes standard with this feature.

There is also a sling swivel attached to the stock, as well as a similar swivel forward of the hand guards. These sling swivels accommodate many of the after-market slings available from several sources.

The thirty-round magazine is shown from both sides in the previous two photographs. To one familiar with the usual ten round magazines found on some commercially available .22 rifles these days, this magazine was a delight! The extensions on both sides of the magazine (for the placement of a thumb and finger) made for an ease of loading which was greatly appreciated. Thirty rounds can be inserted in far less time than it takes to talk about, and the spring pressure never caused any discomfort while loading. The magazine inserts into the rifle's magazine well with a positive "click". Pull the charging handle, move the safety to "Fire", and you're ready to burn some powder!

The magazine fully loaded with thirty rounds of Remington High Velocity .22 Long Rifle cartridges.

Disassembly, Cleaning, and Adjusting the Bolt Speed

The Umarex/Colt M4 .22 LR Carbine is cleaned by placing the safety in the “SAFE” position. Then an empty magazine is inserted and the bolt locked to the rear by operating the charging handle. Remove the magazine and brush out any fouling from the chamber and bolt area with a clean brush and cloth. The bore may be cleaned using a proper solvent, but to insure thorough cleaning, and to avoid damage to the barrel, this must be done from the breech to the bore. I’ve found the easiest way to accomplish this task is to insert the cleaning rod (without a patch) into the barrel, apply a soaked patch through the open bolt, and pull the rod through the barrel. Dry patches will follow this routine until they come out without noticeable fouling. Then all surfaces can be wiped with light gun oil.

Occasionally, the bolt speed might have to be adjusted, to accommodate various types of .22 LR ammunition. In the preceding photograph, the take-down pin is located slightly above, and to the right of the safety lever. This is the same location as the take-down pin on a standard AR15/M16/M4.

Pushing the pin from left to right, the upper portion of the rifle is rotated down, exposing the rear of the mechanism underneath the charging handle. When separating the two sections of the rifle, take care not to lose the bolt-catch/release button. It merely slides into a slot on the receiver, and is held in place by the upper portion of the rifle.

This photograph shows the area where the Allen wrench/hex wrench is inserted to adjust the bolt speed.)

Using the hex wrench provided, the screw is turned clockwise to reduce the bolt speed when using high velocity ammunition. For standard velocity ammo, the screw is turned counter-clockwise. While I did use some standard velocity loads during the accuracy portion of the test, I experienced no problems. Therefore, I saw no need to adjust the bolt speed.

While the rifle is in this opened position, fouling and dirt can be cleaned from the trigger mechanism of the gun.

The Firing Line

A day or two after I had picked the rifle up from Downing’s Guns, my friend and fellow forum member Jason Oliver came by the farm to shoot his newly acquired Colt New Agent. After a period of shooting the handguns, I brought the Umarex/Colt outside. I had around 300 rounds of various high velocity .22 LR ammunition on hand, so we proceeded to put the M4 through its paces. After twenty or so rounds had been fired, we determined that a little sight adjustment was in order. With that minor task out of the way, we shot paper targets, soda cans, gallon plastic milk jugs, and any other inanimate objects that came into view. The only malfunctions were ammunition related. (Someday I’m going to go through a box of Remington .22 ammo without a “dud”!!!!! Yeah, right!)

After Jason left I cleaned the rifle, and made plans to do some accuracy testing with a variety of .22 ammunition. Having fired most of the .22s I had on hand, I went to town to get some more. Hmm, I guess I hadn’t bought any in a while, because the price had doubled from what I had paid for the cartridges I’d fired with Jason. But, I grabbed two 100-round boxes of CCI High Velocity Mini-Mags, two 100-round boxes of Remington High Velocity ammo, and one 100-round box of Remington Standard Velocity loads. Although the owner’s manual suggests the exclusive use of high velocity ammunition, I figure if the standard velocity rounds didn’t cycle the action, I could try cranking up the bolt speed.

I am anything but a rifleman! With my advancing age, I’m fortunate to see 100 yards, much less hit anything at that distance. This holds especially true with .22 caliber ammo, as I don’t own a spotting scope. Without that scope, I would have to do some serious hiking, back and forth, to determine how I was doing on target. So, I set up my targets at fifty yards. With the rifle sand-bagged on my shooting bench, I began the test. I must have misjudged my abilities, because I got some fairly decent groups. I did notice that as the afternoon wore on, I began getting some vertical stringing of my shots. Figuring that it might be due to the fouling of a dirty barrel, I cleaned the weapon, and the good groupings returned.

Please note, I said “good groupings” considering my abilities. I am confident this rifle is capable of much better accuracy in the hands of someone who knows the platform better than I.

Ammo Group inches Group mm
Remington Hi-Vel .22 LR
CCI/Speer Hi-Vel .22 LR HP
Remington Std. Vel .22 LR

For the record, I fired ten 5 shot groups per ammo type, in an effort to get some groups which I felt would be representative of the rifles actual accuracy.

Earlier in this review I mentioned the "false" pins on the receiver. These are located where the pins would be on an actual M16/M4 for removal of the trigger group. Insofar as this rifle is a departure from that design, I could find no similarity between the trigger groups of the two rifles. I utilized the schematic drawing in the owner's manual for this evaluation.

The trigger pull on the test rifle measured an average of 8 lbs. (3,629g), which placed it about midway between the projected trigger pull weights predicted in the owner’s manual. While there was some minor “creep” to the trigger, it did break cleanly. That much weight on the pull probably had an effect on the accuracy. For an example, I would place three shots within a quarter of an inch of one another, and then experience a couple of shots that spread the group out. Most of the shots felt fairly good, but after two hours of trying to get consistent results, I settled for the best I had, to that point. My apologies go out to Walther, Colt, and Umarex for my poor marksmanship.

One other problem that occurred with the Remington ammunition was the frequency of rounds which did not fire. While I previously mentioned the “duds” which occurred during the “fun” portion of the test, I did not keep track of the number. During accuracy testing, I had seven bad rounds in the standard velocity ammunition, and five with Remington’s High Velocity rounds. Luckily for me, those “duds” didn’t reveal any flinching on my part!

Impressions and Evaluation

Take one more look at the Umarex/Colt M4 .22 LR Carbine, with the telescoping butt stock retracted to its shortest length.

The Carl Walther produced Umarex/Colt M4 .22 LR Carbine is made of the same quality materials that set the Colt Model MT6400C apart from the AR15 pack. This is not a statement for debate, as I had the opportunity to compare both weapons side-by-side. I pointed out these similarities in the first part of this review, and nothing in the shooting tests, dismantling, or clean-up of the rifle can lead me to any other conclusion. While there are always markets for firearms which are superior in quality, the question remains if there is enough of a market to continue to produce this weapon. I can’t answer this question except with my own personal opinion.

I have, in the past, spent over $1,000.00 for a Colt M4 type weapon. Later I realized that I never shot it, so it was sold to someone who appreciates the platform more than I. On the same subject, I no longer own any .22 caliber rifles. This is not a condemnation of those guns, as I learned how to shoot with a .22 Marlin rifle, and went on numerous outings with that faithful weapon. Over the course of the last 50 years, I’ve owned a multitude of .22s. Some were great, while others were abysmal. I just realized, at some point, that I no longer enjoyed shooting .22 rifles, so I got rid of them.

The Umarex/Colt ignited in me feelings I hadn’t had since my youth. I got a genuine “kick” out of shooting the rifle, and even enjoyed the repetitiously boring job of testing the weapon’s accuracy. It is a wonderful gun to go out in the woods with. Since there are no large predators in my part of Texas, the thirty round magazine was more than adequate for whatever problems might arise. I obliterated a fire ant mound at 35 yards, which accounted for the total extent of my hunting with the carbine.

To anyone shopping for a look-alike carbine to the Colt M4, I highly recommend the Umarex/Colt. After the initial outlay of funds, the ammunition for the weapon couldn’t be more economical, and the pleasure factor is priceless.


Umarex/Colt M4 .22 LR Carbine
Caliber: .22 Long Rifle
Action: semi-automatic blowback
Overall Length: 34.4" (875mm) (w/buttstock extended)
Overall Height: 9.1" (230mm)
Weight: 6.0 lbs. (2750g) (w/out magazine)
Barrel Length: 16.2" (412mm)
Magazine Capacity: 30 rounds
Price: $450-$630 (dependent on features and retail location)
The various states within the U.S.A. which still have assault weapons bans in effect, may not allow the sale or possession of this rifle.

You may discuss this article


Justin "JB" Biddle is the driving force behind the M1911.ORG E-zine staff getting a crack at reviewing the new Umarex/Colt M4 .22 LR Carbine. Were it not for his enthusiastic conversations with the editors, the decision to publish a non-1911 review might not have been made. Thank you, JB, for your trust in us, as well as the confidence you show toward your company and the fine products Umarex offers to the consumer public.

I can only speak for that portion of Texas from Waco to the Red River, and from Abilene to Texarkana, but in my humble opinion, The Downings run the best gun shop in my small section of the state!


Umarex U.S.A. Incorporated
6007 South 29th Street
Fort Smith, AR USA 72908
Phone: 479-646-4210
Fax: 479-646-4206
Web Site:

Downing's Guns and Family Treasures
516 N. Main Street
Cleburne, TX USA 76033
Phone: 817-641-9999