Shooting the AR15 22LR Conversion Kits

[M-Tecs]

No need Tecs, I found it. This is what I found:

There was also a .22 rimfire conversion designed by U.S. Air Force Master Sergeant Julius V. Jurek. The “Air Force” conversion had a rifled chamber insert, and was gas-operated.

Question arises as to why?

As too the why I don't have a clue. Same for how they compare to the standard M261. The AF versions are the only ones that I have experience with. They did what they were designed to do but compared to a dedicated 22LR upper accuracy and reliability was lacking. I keep my three units mostly as a novelty item for my retro builds. Seeing that the standard M261's are currently selling for more than $350 I may have to rethink that.

My guess is they are 12 twist since they would match the twist of the M-16's they were designed for. The question I've always had about the rifled insert was the effect of having the bullet engraved with two sets of grooves since chances are the insert rifling and the barrel rifling most likely didn't line up.

[Moleman-]

My M261 barrel is a smoothbore.

[TD1886]

As too the why I don't have a clue. Same for how they compare to the standard M261. The AF versions are the only ones that I have experience with. They did what they were designed to do but compared to a dedicated 22LR upper accuracy and reliability was lacking. I keep my three units mostly as a novelty item for my retro builds. Seeing that the standard M261's are currently selling for more than $350 I may have to rethink that.

My guess is they are 12 twist since they would match the twist of the M-16's they were designed for. The question I've always had about the rifled insert was the effect of having the bullet engraved with two sets of grooves since chances are the insert rifling and the barrel rifling most likely didn't line up.

My thoughts exactly. From what I have read the Air Force conversion units were the better ones.

Like Moleman's M261 my Colt unit is a smoothbore.

Another thing I've noticed in pictures of the M261 is it doesn't appear rigid like CMMG or Colt's. In other words the front of unit flexes and you can bend it sort of.

[Larry Gibson]

It's been a long time since I worked with other devices so any remarks I may make regarding them are from memory. However, my comments regarding the quality of manufacture of the M261 as compared to the others back 30 years ago remains consistent. The quality and performance of the m261 is what sold me on its selection for my own use. Also, the magazine inserts working with standard 5.56 mags was a plus.

Also, the reason I wanted an M261 for use with a 12" twist AR was the versatility. My use for it is casual plinking or small game hunting. I had no illusions of it being as accurate as any of my 5 bolt action 22LRs or either of my 10/22s. I've no need or desire to have a dedicated upper or a wannabe 22LR AR look alike. No criticism for those who do, just not what i want. The M261 with a couple mag inserts weights little and doesn't take up much room in my shooting box or in a "bug out" bag if necessary. With it I can quickly convert my suppressed 5.56 AR into a suppressed 22 LR. I don't use it for combat practice as I've plenty of 5.56 for that. What the M261 device does is just what I wanted it for.

As to accuracy, the last zero/group test with the EOHteck(?) sighted AR (12" twist) I ran was an informal 20 shots of swaged Winchester bulk at 50 yards off the bench [forearm hand laying on sandbag, no rear rest]. That group was just under 2" which is close enough for me. Tomorrow morning at first light will find me at the range to test the accuracy of various different 22LR ammunition. Some I will test both out of the box and swage while other will be just out of the box. The reason is swaged does distort the bullet nose and some rounds will not feed reliably if swaged enough to bring the drive bands up to .225 diameter.

Note from the pictures the chamber insert is pined to the rest of the assembly on the left side. This can seemingly be a problem, but it isn't. The m261 chamber insert fits solidly in the barrel extension and chamber. Note also the neck of the insert is about 1/3 the length of the chamber neck as compared to the cartridge next to it. The throat on the chamber part of the M261 is smooth and pin gauges .225 - .2245 at the muzzle end.

[TD1886]

It's been a long time since I worked with other devices so any remarks I may make regarding them are from memory. However, my comments regarding the quality of manufacture of the M261 as compared to the others back 30 years ago remains consistent. The quality and performance of the m261 is what sold me on its selection for my own use. Also, the magazine inserts working with standard 5.56 mags was a plus.

Also, the reason I wanted an M261 for use with a 12" twist AR was the versatility. My use for it is casual plinking or small game hunting. I had no illusions of it being as accurate as any of my 5 bolt action 22LRs or either of my 10/22s. I've no need or desire to have a dedicated upper or a wannabe 22LR AR look alike. No criticism for those who do, just not what i want. The M261 with a couple mag inserts weights little and doesn't take up much room in my shooting box or in a "bug out" bag if necessary. With it I can quickly convert my suppressed 5.56 AR into a suppressed 22 LR. I don't use it for combat practice as I've plenty of 5.56 for that. What the M261 device does is just what I wanted it for.

As to accuracy, the last zero/group test with the EOHteck(?) sighted AR (12" twist) I ran was an informal 20 shots of swaged Winchester bulk at 50 yards off the bench [forearm hand laying on sandbag, no rear rest]. That group was just under 2" which is close enough for me. Tomorrow morning at first light will find me at the range to test the accuracy of various different 22LR ammunition. Some I will test both out of the box and swage while other will be just out of the box. The reason is swaged does distort the bullet nose and some rounds will not feed reliably if swaged enough to bring the drive bands up to .225 diameter.

Note from the pictures the chamber insert is pined to the rest of the assembly on the left side. This can seemingly be a problem, but it isn't. The m261 chamber insert fits solidly in the barrel extension and chamber. Note also the neck of the insert is about 1/3 the length of the chamber neck as compared to the cartridge next to it. The throat on the chamber part of the M261 is smooth and pin gauges .225 - .2245 at the muzzle end.

Not that I want a pat on the back, but thought you would say something about my initial testing just to see what I was working with. Also about the modification I made. After that mod, plus swagging, the 7 twist looks (and I say that with a big if) proming. I made a post here waiting on your opinion if I should post that modification. I will be moving the target out further and now I have a parameter, your two inch group at 50 yards. I personally think that is pretty good with an AR15 and using the device.

[TD1886]

Was talking to Larry Gibson through pm's and he asked I post the pics of my Colt conversion. So here they are:

[TD1886]

As per my pm conversation with Larry Gibson he said he saw no reason why I couldn't post the modification I made to my conversion unit. What I did was open the bore (lack of description) up with the proper size reamer to match the size of my swaged bullets. As I mentioned this made the largest improvement in accuracy on my intial first testing, by which means not conclusive. I will be further testing out to 50 yards. I just hope it holds up at that distance.

It's been brought to my attention that the "bores" on these devices vary pretty much. M-Tecs brought to our attention that the Air Force devices are rifled! He is correct about that as I didn searches on that to find it. Both he and I wonder why the did this. Larry said he couldn't figure it out either.

So Tecs you have your answer.

I edited to add that it makes no sense to swage if the "bore" of the device squeezes the bullet down smaller then the groove diameter of the 5.56/223 barrel.

TD

[barnetmill]

Was talking to Larry Gibson through pm's and he asked I post the pics of my Colt conversion. So here they are:

Apparently from what i understand the colt system uses some sort of modified M16 magazine for the .22 lr. The cmmg unit uses a specific mag that I think takes 25 rounds. They work ok for training, but not for anything where a malfunction is absolutely a no no. I have a loader specifically set up for reloading the CMMG mags.

CMMG .22LR 25 Round Magazine, Black - 5 Pack on sale for $54.99 marked down from 129 or so dollars.

[M-Tecs]

Thanks for the answer.

I looked closer at mine. The rifling in the insert is much shallower than normal rifling. I'm just in the process of bringing another lathe into my basement shop and everything is a mess. When I get things organized I will do some measurements.

[TD1886]

Apparently from what i understand the colt system uses some sort of modified M16 magazine for the .22 lr. The cmmg unit uses a specific mag that I think takes 25 rounds. They work ok for training, but not for anything where a malfunction is absolutely a no no. I have a loader specifically set up for reloading the CMMG mags.

CMMG .22LR 25 Round Magazine, Black - 5 Pack on sale for $54.99 marked down from 129 or so dollars.

Colt has some kind of 22 steel magazine inside that plastic outer sheall that resembles a 20 round AR15 magazine. It's basically a piece of junk, but it works. I'm like to know what brand Colt grabbed for that steel magazine insert as I know damn well they didn't make it themselves. Colt was good for farming out parts.

[TD1886]

Colt has some kind of 22 steel magazine inside that plastic outer sheall that resembles a 20 round AR15 magazine. It's basically a piece of junk, but it works. I'm like to know what brand Colt grabbed for that steel magazine insert as I know damn well they didn't make it themselves. Colt was good for farming out parts.

That's great, would like to know what you find out. Soon as this damn rain stops I'll be testing at 50 yards. I have a parameter that Larry Gibson didn't really set, but he said his 12 twist AR15 shoots 2 inches at 50 yards. BTW he was out this morning before the birds even get up shooting his again for a big report on here. So I have to at least get 2 inch groups at 50 yards. As I said it really shrunk my groups at my intial testing at 25, which basically was to see how this unit functioned in my rifle.

[TD1886]

I braved the rain and did some quick shooting as conditions weren't ideal. I had three different brands of ammo. PMC, Remington, and Browning. These were all swaged. Sorry M-Tecs didn't get to test the non swaged rounds YET.

30 rounds total. Okay what I'm noticing is that there are fliers, not many, but they are bad. There are so many things that can influence this as inconsistency in swaging, movement of the devive in the chamber, even the ammo. Alright I can tell you my old HBAR 7 twist shot mos, that's minute of squirrel at 50 yards. The target distance was measured with a Nikon range finder. I met that 2 inch goal at 50 yards I set for myself. Another thing that affected my shooting was that I'm a stickler for not wanting to adjust my scope for the 22LR conversion kit. I have it sighted in for the 70 gr Speer Semi Point which it shoots better then good. I was shooting almost six inches to the right and six inches low. So I used the horizonal reticle where it goes from the fine crosshair and then turns into the thicker duplex. I wasn't concerned about elevation as the target was big enough that way to catch them all, but not catch them shooting six inches to the right. So using that plex definitely moved it to the left. When I go again I will make a target that I can aim at the bullseyes with the crosshairs and catch them all.

I had some tight groups out of those 30 rounds. One group was 3/4 inches. There were also 3 bullets into 1/4 inch in another group. Aiming with that duplex junction isn't the greatest for accuracy. Tomorrow it's supposed to be nice.

As it is with insufficient testing the 7 twist isn't hurting the 22LR too much AS LONG AS THE BULLETS ARE SWAGED FAT! It remains to be seen what my modified device shoot unaltered non swage 22 LR ammo as M-Tecs request. Sorry Tecs I'll get to it I promise. Do out of the 7 twist, the .224 groove diameter, and the 22LR bullet being up to speed when it hits that 7 twist groove angle, I'm going to say early it's the .224 groove diameter doing the most in inaccuracy, couples with the 7 twist rpm amplying it. If that undersized bullet isn't straigh in the bore the 7 twist will tell the most.

[Larry Gibson]

Was at the range at 0520 as dawn was breaking. Was 89 degrees. This test is a simple one with 10 shots of several different makes/styles of 22LR ammunition. Some were tested both as OOB (Out Of the Box) ad as swaged with the Waltz die which refoms the HP along with uniforiming the drive band diameter at .225. The M261 device was installed in my AR15 with a 12" twist milspec M16A1 barrel. A Gemteck Suppressor was on the 20" barrel. Sighting was done with and EohTeck mounted forward over the handguards. Sight picture was putting the 1 moa dot in the middle of the 2.25" aiming black at 50 yards. All groups were 10 shot groups with the target at 50 yards. I shot 12 different groups with the 12" twist AR/M261.

When finished with the 12" twist AR/M261 testing I switched the M261 to my 9" twist Colt HBar. It is a heavy barrel match rifle with a floating barrel inside a tube fore end. It has a 1.5 - 4X Leupold scope on it. With quality jacketed bullet ammunition, it shoots 10 shot groups about half the size the 12" twist AR does. I attribute a lot of that better accuracy to the use of the scope vs red dot. Anyways with the HBar, I selected three different loads to test for comparison of accuracy to the 12" twists accuracy with the same loads.

As soon as I had sufficient light to shoot accurately, I began the testing. I completed the testing about 0730. By then it was 92 and the Sun was shining onto the firing line. I swabbed the chambers of both rifles out with a 30 cal patch and then ran a 22 cal patch through the bore. The CF 5.56 BCGs were put back in and 10 rounds of M193 was fired through each rifle. No malfunctions occurred.

The test groups with the 12" twist milspec M16A1 barrel;

Federal ValuePak 36 gr HV HP Waltz

Federal Valuepak 36 gr HV HP OOB;

Winchester SuperX HV HP OOB;

Winchester SuperX HV HP Waltz;

[Larry Gibson]

Continued;

CCI Standard Velocity Target Waltz;

CCI Standard Velocity Target OOB;

Remington Golden Value Pak Waltz;

Remington Golden Value Pak OOB;

[Larry Gibson]

Continued;

CCI Velocitor OOB;

CCI Stinger OOB;

Remington Yellow Jacket OOB;

Winchester 525 Bulk Pak Waltz;

[Larry Gibson]

Continued;

Loads tested with Colt HBar with 9" twist;

CCI Velocitor OOB;

Remington Golden value Pak Waltz;

CCI Standard Velocity Target OOB;

Note the increase in group size compared with the same load fired in the 12" twist. This why the 12" twist suits my needs. Six of the 12 ten shot groups were well under 2" with one right at 1". That load is subsonic and quite quiet with the noise mostly heard is the action functioning and the bullet whapping into the target.

[TD1886]

I noticed something that your rifle does that mine does. With the regular HV 22LR's and there are those fliers. Mine starts grouping, then there will be some fliers. As I mentioned there are so many things that can influence then when using the conversion kit. You take my 22 bolt rifle and there are not fliers even with the HV 22LR fodder. I need to determine what is causing that in the converson unit. I had three Brownin'gs 22LRs that didn't fire. You know that AR15 hits that firing pin dang hard too.

I'll get out when it's nice and do the test in a more professional manner. I don't have any target 22LR ammo and not going to buy it either.

[barnetmill]

Larry G.
I see that a bare lead standard velocity load did the best. The legend said CCI SV target load and I assume it is what most of us try to shoot in our S&W model 41 pistols for bullseye. There is also a match version of it I believe.
I just put in an order for 5,000 rd case of it that will last me for about 53 bullseye matches at about 7 cents around.
Good to know how well it can group in a rifle.

[Larry Gibson]

TD1886

I believe you're missing the obvious. Your bolt guns do not give flyers with the same ammunition because they have a 14 or 16" twist. The results the guy had in the video are because of the 8" twist of his AR. My 12" twist shoots 22LR better than the 9" twist because of the slower twist. In the past I have shot enough 22LR with M261 devices (multiple devices in multiple different ARs/M16s) with 12, 9 and 7" twists with the 12" twists always giving better accuracy than the 9 and 7" twists rifles. The 9" twists always gave better accuracy that the 7" twists. You are using a 7" twist so there in ls the answer. With sufficient testing you may find a particular lot of 22LR ammunition that may do reasonably well enough for some types of shooting as did the author of that video. However, finding consistent accuracy useful enough for minute of small game may prove very elusive with your 7" twist rifle.

It is the twist.

Don't let that "Target" designation on that CCI ammunition fool you. I got it last year in several Walmart stores and Sportsman Warehouse in Vegas last year. I paid $4.99 and $5.99 a box for it. I see in the just received Natchez flyer they have it for $3.99 a box.

As to misfires. I've found that the use of lead bulleted 22LR with a wax lube leads to a residue buildup on the bolt face around the rim area. This prevents the bolt from completely closing. The rear of the firing pin doesn't stick out very far on my M261 and if the bolt is even slightly not closed it will also misfire. This is a common issue with my 10/22s and other semi auto 22LRs. It's why I prefer to use only copper plated non lubed 22LR....much less buildup of such fouling on the bold face. The Remington Golden, the Federal ValuePak and the Winchester 525 Bulk are such and are what I mostly use in my AR/M261. I also prefer the CCI MiniMag and Remington Yellow Jacket in my 10/22s for hunting. The CCI Blazers and other lubed lead bulleted 22LR ammunition I use in my bolt guns.

[Larry Gibson]

Larry G.
I see that a bare lead standard velocity load did the best. The legend said CCI SV target load and I assume it is what most of us try to shoot in our S&W model 41 pistols for bullseye. There is also a match version of it I believe.
I just put in an order for 5,000 rd case of it that will last me for about 53 bullseye matches at about 7 cents around.
Good to know how well it can group in a rifle.

I certainly was pleasantly surprised as I bought it mostly for the stated subsonic velocity for use with a suppressed bolt action rifle.