Brownells .22 rim fire AR-15 Conversion unit By Peter M. Reiff Sr.

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Brownells .22 rim fire AR-15 Conversion unit
By Peter M. Reiff Sr.

Download PDF for an easier to read and print version complete with photos.

The past three years has been interesting for firearms owners in the USA. One of the current political administrations “babbling heads” made an off the wall comment about “banning ammunition” being a Democratic Party agenda. The resultant hysteria justifiably resulted in pandemic purchases of said product by the citizens of our fine country. Many of whom had been mistakenly supported for election to office the above clowns based on Demo Party Dogma, and their media saturation catch word “CHANGE”.

About the only ammo that could be readily found was cheap .22 rim fire, all else disappeared in pallet sized lots as soon as it hit the distributors in most regions.
That ammunition which was obtainable was marked up to astronomic prices by bottom feeding scalpers and fear profiteers. For those of us who are required to continually re certify to remain authorized to legally carry a firearm life became just a wee bit more challenging. Qualification ammunition often required hours of phone calls and travel to obtain “enough” to simply shoot a mandated course of fire….

Those whom view regular firearms training as a necessary combative skill to stay alive obviously practice far more found even more hardship just to keep the edge. If you seriously train more often, you should perform in a superior manner during a sudden unexpected horrific event.

Like it or not firearms are the “Martial Art” of the new millennium for the vast majority of people. Simply put, no matter how “BIG” or “Bad” your fighting prowess a precisely placed projectile will negate all deadly hostilities quicker and with less risk of personal injury than any other combative system. BUT, you must remember the old adage “Perfect Practice makes Perfect Skills”. Especially should other citizens/clients depend on your skill to survive they have to be done EXACTLY right the first time.

My employer has a strategically located placard in one of our classrooms which reads “If you knew you would be fighting for your life tomorrow, would you change the way you train today?” For me personally this means practicing as regularly as possible with multiple typologies of handguns, a couple shotguns, and AR-15 carbines came to a dead stand still. No ammunition resulted in a screeching halt to regular training………..

Recently I obtained a .22 rim fire conversion unit for my AR-15 platform from Brownells, Inc. The kit is made for Brownells by CMMG, Inc. whose rim fire conversions have a deserved reputation for both reliability and accuracy.

The largest selling point for me being the kit came equipped with three 26 round magazines! Normally .22 conversion kits are shipped with a solo 10 round magazine and often “Good Luck” finding additional magazines for practicing various courses of fire or tactical drills.

These magazines are made from a light weight synthetic and have a number of neat “engineered ins”:

Smoke colored synthetic body allows for quick verification of rounds loaded or remaining. Integral structural braces help to keep the magazines together should they be dropped, or rammed home with a little too much panache.

The high visibility follower incorporates a rounded anti tip follower and linear coil type spring which aids in preventing the rounds from becoming misaligned while loading or discharging the magazine. These magazines lock the action open when empty too!

An Integral window in the base of the magazine body allows for the floor plate to be removed easily for cleaning or periodic maintenance.

The high visibility floor plate can be removed with a pen tip or any similar object and easily slides into the molded slot in back of magazine base.

The Magazine body can also be taken apart by removing six recessed hex screws (that thread into corresponding molded in brass inserts!)

All of these features make field testing and practice sessions far less tedious with more time spent shooting. The only thing missing is a numerical round count molded into the body, but that can be easily remedied.

The practical applications of this conversion unit for training are vast.
Economy - .22 rim fire rounds can often be purchased for less cost than top end air gun ammunition. It can also be readily found in almost any region of the USA should you be hosting or attending a seminar or just travelling “well heeled”. The .22 rim fire cartridge has a low noise signature allows training to take place in times and places utilization of conventional AR-15 platform center fire ammunition would be intrusive.

How it works- Direct blowback mechanism is simple and reliable and can be stored in the original shipping tube, or your choice of rigid case.

To install the kit in the field as needed for practice or training purposes this is what you do:
Clear the rifle while pointing it in a safe direction

Remove the bolt carrier, replace it with .22 conversion unit, close the receiver, then load and shoot. That simple!

A dedicated .22 rim fire AR-15 platform rifle can be set up giving familiar piloting controls to all end users. If it needs to be redeployed as Center fire, simply swap out carriers and re zero.

No need to purchase, or carry a secondary brand or typology of rifle, and all of the peripherals for operation. The need for an additional “specialized” rifle (aka integrally suppressed Ruger 10/.22) fades to simply swapping a dedicated (and pre zeroed) upper receiver which can be carried with minimal space and inconvenient.

Specialized environmental applications such as pest removal, guard animal negation, vehicle tire neutralization prior to a raid, or removing undesired illumination can all be taken care of with one rifle / training platform. If necessary removable low noise signature devices can be fitted to the muzzle of most AR-15 series rifles via either the OEM muzzle brake or the existing ½-28” thread. There are a host of them legally out there for the price of a tax stamp and some necessary paperwork.

The use of either .22 LR Subsonic rated, or the newer generation “CB” hollow point type ammunition can almost make the use of low signature devices a moot point depending on ambient environmental noise conditions, and without the worries of administrative regulatory paperwork, transfer taxes, local potentate approvals, additional tags, and the supersonic crack.

Price - normally first question asked $ 199.95 (the local retail equivalent to100 rounds of generic .223 ball ammunition.)

The total cost for the first five hundred rounds of ammunition used during the evaluation of this conversion kit was less than the cost of filling the gas tank of my car for two trips to the gun club.

Accuracy- I evaluated the Brownells unit for accuracy and reliability with a number of ammunitions at distances of 7 to 50 yards. The ranges could have been stretched to 100 yards or more but the optimal ballistic parameters of such a conversion rapidly lose value.
This Brownells conversion unit was as accurate as any out of the box non customized semi-automatic .22 rifle that the author has tested. While not within the accuracy parameters of a custom or “tuned” rifle, still well within reason shooting a total aggregate average of about .680” for the first five hundred rounds fired. Groups were fired at about a one round per ten second cadence, with cooling and cleaning between ammunition brands.
Many of the premium .22 rim fire ammunition groups were VERY good averaging under ½” c.t.c. at 25 yards and hovering around 1 ½” at fifty yards. This unit seemed to prefer either Eley Club or CCI Sub-Sonic rounds over all else.

Rapid fire testing and a number of tactical drills all could be performed with no reliability issues and with either iron sights, or optics. With the rifle “locked in” it was errie to not have the sights recoil shift during move and shoots exercises.

Installing a true match trigger unit, and re-parallaxing the top end scope for closer range to improve accuracy will be discussed in a follow up article once the weather breaks in my neck of the woods.

Figure .22 LR CCI Sub-Sonic Hollow point by chamber area
Before you dismiss these findings remember the projectile must travel a free throat distance of about 1.640” before engaging the rifling of the actual .223 rifle barrel. That folks is a fair amount of jump for a round that headspaces off the rim!

Additionally the carbine rifling twist rate is a very quick 1:9” as opposed to the conventional 1:16” used in the firearms industry.

Also the primary affixed test scope a Leupold 3.5-10x40 MKI is parallax corrected for 100 yards and was not recalibrated for 25 or 50 yard shooting resulting in a slight distortion of target and reticle affecting precision aim.

25 yards - Five 10 shot groups BEFORE zeroing the Brownells conversion unit

Reliability – Often a very BIG concern with a conversion unit is will it work when needed? The very early first generation Atchisson .22 rim fire conversion units had less than a sterling reputation for reliability. Partially due to sloppy manufacturing tolerance, partially due to cleaning and maintenance, and partially due to poor engineering design of the magazines or using ammunition which did not generate enough of a recoil impulse to cycle the action….

The Brownells conversion had VERY few bobbles, a total of five rounds failed to feed while seating the unit as fitted directly from the shipping tube. The same box of older Remington bulk ammunition also failed to fire in a number of other .22 rifles and pistols.
In addition to the Mfg. recommended high velocity rounds, I tried a number of sub-sonic variations from Eley, CCI, Remington, RWS, and Winchester. Contrary to the instructions there was only one failure to extract with a Remington Subsonic round out of over three hundred fired. No other malfunctions occurred with any of the full powered evaluation ammunition for the first part of the testing.

Primer only powered .22 long rifle “CB” rounds from CCI, and Remington was tested but the lack of recoil energy effectively made the carbine a repeating single shot when the rounds could be extracted. The audible report was comparable to a high end pellet rifle and accuracy at 25 yards ran .643” CCI /.588”Rem

If you are on a budget, or want a multi purpose carbine without having to purchase a dedicated .22 rim fire upper the Brownells packaged unit certainly worth looking into.

Download PDF for an easier to read and print version complete with photos.


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