AR-15 .22LR Conversion Kit: Worth It?

Is a .22LR conversion kit a reasonable purchase for a prepper, or is it better to get either an actual AR-15 chambered in .22LR or a dedicated .22LR upper? 

Let’s take a look at my experiences with a conversion kit and perhaps it will help you decide what is right for you.

Conversion Kit = Lower Cost Per Round

The idea behind the kit: train with your own gun, but at a much lower cost per round. 

On the surface, how much money you save depends largely on how many rounds you shoot with your AR-15… While this is true, it doesn’t tell the whole story.

I’ve long held the opinion that people will train more if the cost of training is lower. Here’s an article I wrote recently about this concept.

I’ve shot an AR-15 two weekends in a row now, looking into various ways of “going cheap” with training ammunition. Last weekend we shot only the cheapest “rot gut” steel cased ammo we could find, Tulamo .223. I’ll be doing more with steel cased import ammo in the near future, but for now let’s look at today’s shoot and compare/contrast it from both a financial and shooting point of view.

The Numbers

I’m going to use the actual cost of what I paid out of pocket for each of these three ammo types as my comparison to see if a .22LR conversion kit is worth it’s cost.

Today I shot 250 rounds of Remington Thunderbolt High Velocity .22LR, my prefered “cheap bulk” .22LR ammo. I picked up four 500-round boxes when I stopped by Midway USA a couple of weeks ago (I love picking stuff up their in person). Cost of the boxes were $14.99, and sales tax was $1.33 making the cost-per-round .03 cents (I’m rounding but it was close so let’s stick with whole numbers). 

The Tulammo I was $200 for 1,000 rounds shipped from an online source (Sportsman’s Guide), making it (not hard to figure this one) .20 cents per round.

Normally I shoot Federal American Eagle, the most recent batch I bought for $50.34 for 150 rounds from Sportsman’s Guide, shipped (I am a member of their “club” so shipping is free on orders over $50, a good deal for heavy stuff like ammo). This is good, high quality re-loadable brass, but it slots in at .33 cents per round.

Bottom line? I can shoot an entire magazine’s worth of .22LR for the price of two Federal .223 rounds.

OK, fine, it’s cheaper to shoot… what is thing conversion kit anyway?

There are several different ones out there, but the basic models contain two components.

• A .22LR specific drop-in bolt carrier group (BCG) that replaces the standard BCG in an AR-15 upper receiver.
• A .22LR specific magazine

Optionally, a lot of kits include a separate charging handle, but in all honesty you don’t need that. I’ve tried them both ways and found no difference in reliability. 

The conversion kit I have is the CMMG Bravo, it’s about three years old but it hasn’t been used much. Why? No, it’s not that I dislike the kit, I just didn’t own an AR-15. When we switched our main personal defense carbines over from our Windham Weaponry rigs (excellent guns) over to Tavor X95 bullpups, we sold all of our AR specific stuff except the conversion kit.

Honestly, it was stored away and I forgot about it until I opened that bucket up about six months ago to break out some fresh P-Mags. 

Salty’s Note: Truth to tell, I’m not a big fan of the AR in general, I don’t find them particularly comfortable to shoot, nor do I care for their balance. The only reason I purchased another AR-15 is a project I’m working on that I will share here on 3BY in the future. 

Wait A Minute… Shoot a .22LR Bullet Down A .223 Barrel? Seriously?

Yes, seriously. The AR in question today is a Del-Ton Echo 316L flat top wearing a Sig Sauer Romeo 4H red dot. The gun features a 16-inch barrel with a 1/9 twist and is chambered in .223/5,56 NATO.

While the 1/9 twist is a great barrel for a 45-77 grain light-to-mid-weight bullet, it’s not what one would pick for a higher performance .22LR round. For comparison’s sake, a Ruger 10/22 will come stock with a 1/16 barrel.

A 1/9 twist rate is sometimes used in a .22 round, generally for the slow, subsonic rounds (ones that might not have enough force to cycle an AR-15 action).  

If you are unfamiliar with barrel twists, what this means is how far a bullet will travel in inches before it rotates one time.

Does Size Matter?

If you look at the two bullets, a .223 shell is MUCH larger than a .22LR, so how can the bullets from both of those shells go comfortably down the same barrel? Well, it turns out that while a .223 round is much more massive, it’s only SLIGHTLY bigger across the base.

A .22LR round is actually .223mm wide, while a .223 round is actually .224mm wide (don’t blame me, I didn’t name this stuff). A 5.56 NATO bullet is also .224mm wide, the differences between that round and the standard .223 are real, but not relevant to this article so… yeah, let’s skip those.

Does that .001mm make much difference in accuracy? No, it doesn’t.

Having said that, the barrel twist rate does.

A .22LR conversion kit will not be quite as accurate in a .223/NATO upper as would a purpose built .22LR gun with a 1/16 twist rate with standard .40 grain high velocity ammo like the Remington Thunderbolt I was using.

How Close Is “Not Quite”

To give you an idea of what “not quite” means I fired 100 rounds into a target today placed at 50 yards. I fired off of a bench rest, while seated, using the previously mentioned Del-Ton, an inexpensive mass-market AR-15 with the Romeo 4H optic. The optic isn’t magnified, so one limiting factor is the shooter’s old eyes.

Here’s my 100 round group (Note: The one flyer at the top is my fault, not the gun’s. A mosquito landed on my shooting hand and was preparing to chow down on ole Salty. I pulled the shot, and the mosquito had an even worse day).

Another thing to note is that the Romeo was sighted in last week on Tulammo .223 at 100 yards. I made no adjustments whatever. Discounting the mosquito flyer, the group was about 4 inches at 50 yards without magnification… a better shooter (or me with a scope) could undoubtedly put together a much tighter group at 50 yards.

Manual Of Arms

The manual of arms (operation of the gun) is, not surprisingly, very close to the same as when using the standard .223 bolt & magazine. There are several noticeable differences, however.

• The bolt hold open is based on the magazine, so when you pull the mag, the bolt snaps shut.
• This means that training to use the bolt catch button (the big button on the left side of the gun that allows a locked-back bolt to close) isn’t going to happen with this conversion kit.
• The charging handle pull is about one-third of what it takes to pull a regular .223 bolt.
• The trigger has a “funky” feel to it during reset… there’s a definite strong catch to it that you don’t feel with a standard BCG.

Other than these items, it’s the same gun so all of the ergonomic stuff just works.

Reliability Of The Conversion Kit

I have shot many thousands of rounds through this CMMG conversion kit, and I have found it to be as reliable as most .22LR guns are. 

It’s not perfect, but the .22LR round is far from perfect.

Today I shot 250 rounds of $14-per-500 ammunition through it, and I had one jam. It came on a failure to eject at around 200 rounds. Here’s what it looked like.

The jam was inside the BCG so to clear it, I simply popped open the back of the gun and pulled the BCG out.

The Del-Ton has been a very reliable gun, and I’ve been somewhat surprised by the reliability of the CMMG conversion kit.

As you can see from the picture below, it gets really, really dirty from .22LR ammo.

I don’t mind the occasional jam in a training gun, it allows me to work through clearing the gun in a safe, efficient manner. That’s good training as well. Where I start to not like jams is if they occur enough to bust my groove.

This rig jammed once in 250 shots. I can live with that.

Wrapping it up

Is it worth buying one of these conversion kits if you have an AR-15? The CMMG one featured here retails for $199 but you can find it cheaper on the internet. This is one item I would never buy used, since it’s something that, if dropped, can get really messed up. 

In light of the fact that you can buy, for double the money, an actual AR-15 designed from the start to be a .22LR AR, it’s hard for me to recommend this conversion kit unless somebody wants to use one gun and only one gun.

Me? I’ve got it so I will use it, but if I were buying today I would probably just get an Smith & Wesson AR-15 .22 unless I had a fancy optic like an ACOG that it’s too expensive to buy multiples of.