Training with sub-caliber firearms

With a sub-caliber trainer, an officer can shoot a whole day for the price of a box of bullets, with trigger time concentrating on skills drills

As we continue our focus on training products, I just got back from the range after using a product that every department should have in their inventory: a sub-caliber training device. Since I needed to train on my AR-15, the best sub-caliber is .22 LR. I went to my friends at Franklin Armory after checking to see if they had a CMMG sub-caliber converter I could borrow.

Franklin Armory is a manufacturer of quality carbines based out of Morgan Hill (Calif.), which is about an hour south of the PoliceOne headquarters. You’ll hear more about Franklin Armory products when I review products from ERGO Grips in a month or so.

There are plenty of drills appropriate for using a sub-caliber conversion. These drills all have a common goal: trigger time. Combined with deliberate dry-fire training, trigger time (or time on trigger) is the way to achieve competency levels necessary for lethal engagements. For a great discussion on dry firing with a handgun, see Ron Avery’s article on high-performance dry-fire training concepts.

A CMMG .22 Conversion Kit takes seconds and is as easy as swapping the bolt carrier group for the drop in kit. (Image Courtesy of CMMG)
A CMMG .22 Conversion Kit takes seconds and is as easy as swapping the bolt carrier group for the drop in kit. (Image Courtesy of CMMG)

Cheaper by a Bundle
With a sub-caliber training device, an officer can shoot a whole day for the price of a box of bullets. Recoil is significantly reduced and shooters can concentrate on skills drills. The more time on trigger, the better the shooter becomes.

Shooting statistics show that when officers shoot under time pressure, their accuracy diminishes, at least with the things we know about field shootings with handguns. If we were to compare shooting qualification rates with actual shooting hit rates, which include time- and emotional-pressure, there is a severe disparity. However, training data in any agency can consistently show that trigger time improves accuracy and the ability to deliver accuracy faster. If combat accuracy numbers are a subset of training accuracy numbers, it is a logical step to increase shooting speed and accuracy by getting trigger time. The next step in logic is the fact that agencies almost cannot afford to employ sub-caliber training.

I do very simple drills with sub-caliber AR-15s. A couple of weeks ago, I used a 25-yard range with an open floor and target stands I could rearrange. I put two stands seven yards apart, one in front of the other. Using good movement techniques, I approached both stands, firing controlled pairs at the front target, then sliced the pie into the second, finishing with a controlled pair. In another drill, I use the front stand as a barricade and fire left and right side, under and prone in smooth transitions. Last, I practiced moving and shooting, transitioning to my handgun.

One can shoot at a faster cadence with a sub-caliber trainer, which offers powerful psychological reinforcement.

Sub-caliber training should be deliberate, with the focus on smooth techniques. These drills cost me about a dollar in targets and two dollars in bullets for three hours of practice. I have three bricks of .22s in my closet (1,500 rounds) so I anticipate that I may spend a little of my time off this week behind my Franklin HSC-15.

Conversion Kits
CMMG makes .22 LR conversion kits for gas-impingement type AR-15s. The drop in kits can generally convert a duty AR-15 to a .22 LR in less than a minute, provided the user selects the correct conversion and follows the instructions carefully.

The CMMG conversion, and most similar products, uses a replacement bolt that engages the chamber, and a bolt group, which replaces the original bolt carrier group. It is essentially one-piece and field strips the same way. The sub-caliber group turns the gun into a blow back set up. It uses a magazine which operates in the well, with a smaller inner body and follower. I recommend that the agency purchase several magazines for realistic training. I didn’t experience any failures, except my ability to X the target.

There is no more a couple thousandths of an inch between the bullet diameter of a .22 LR and .223. The .22 LR bullet diameter is .222 and the .223 (and 5.56) diameter is generally .224. Although a .22 LR generally needs a slower rate of twist than the larger cartridge, generally around 1/16 (see Dennis Hayworth’s discussion on twist rate), the 25 yard training distance for a sub-caliber trainer is forgiving enough for most variations in twist rates used by LE. With my set up, I could easily shoot 1/2-- inch groups at 25 yards, exactly where the .223 bullet would impact, regardless of the 22LR bullet.

I recommend using plated .22 LR bullets, simply because they will respond to the same cleaning agents as the .223/5.56 to which the gun is accustomed. No user has ever reported a leading issue or any concern with fouling of the LE firearm.

Three Alternatives
There are three distinct routes to sub-caliber training: Drop in conversions, dedicated uppers, and dedicated firearms. I prefer the dedicated upper that fits on the officer’s lower without modification, provided the same optics and fixtures are on the sub-caliber trainer. Most agencies cannot afford to duplicate the optics and fixtures on a dedicated upper and will likely use a drop in conversion.

Regardless, use the closest thing to a set up to the actual duty firearm. It would be foolish to train in the saddle for years and go into battle riding a different horse.

I viewed some of the forums about drop in conversions before beginning my research on this article. Many users, including LE agencies, report that companies that make sub-caliber conversions are notorious for marginal customer service. I don’t know if this is true, but I can attest to the fact that two of the companies have not returned calls, despite six messages, followed by emails over several weeks.

I know a solution for this: Brownells sells a variety of conversions and AR-15 parts, answers customers questions promptly and is the “LE-friendliest place around. In fact, they even have an address just for us:

One final thought: Now that PoliceOne Senior Editor Doug Wyllie knows that there is a carbine manufacturer within an hour of his office, I expect he’ll want one too, since he has a penchant for fine carbines. I’ll meet you there Doug!

About the author

Lindsey Bertomen is a retired police officer and retired military small arms trainer. He teaches criminal justice at Hartnell College in Salinas, California. He has a BS in Criminal Justice and an MS in Online Teaching and Learning. Lindsey has taught shooting techniques for over a decade. His articles on firearms tactics have appeared in print for over a decade. Lindsey enjoys competing in shooting sports, running, and cycling events.

Contact Lindsey Bertomen

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