Shooting the AR15 22LR Conversion Kits

[TD1886]

Larry Gibson give your opinion on the questions I have asked please.
I wanted to discuss the 7 twist and these conversions. Let's say you have a velocity of a 22LR bullet using that kit from a 20 inch barrel of 1250 fps. That would be 128,571 rpm. What is your opinion that destroys the accuracy in the 7 twist, the incompadible diameter of the 22LR bullet to the .224 groove, the rpm of the bullet, or the fast twist is somehow ruining the very soft bullet to cause it be inaccurate. I also thought that some people get half decent accuracy with cast bullets, but they are usually longer, not as soft as the 22LR, and they fit the bore/groove much better. What do you think is the problem? Thanks in advance

[TD1886]

Larry wanted me to start a new thread on this in another thread I asked him about it, so I'm waiting for him to catch up.

[Larry Gibson]

Many irons in the fire here at home. My thoughts;

Using the M261 in 20" ARs with 7 and 12" twists; The difference between the two barrels given the use of the same 22LR ammunition at 1250 fps is substantial. While the 12,571 RPM with the 7" twist may seem sublime yet it still falls within the RPM Threshold range of 120 - 140,000 RPM. With the 12" twist AR the RPM is 75,000, substantially lower and well below the RPM Threshold range.

Additionally, a 22LR round in the M261 will have a 1.7" +/- free bore jump before it hits/engages the lead in the chamber throat. Obviously, the sharper angle of the 7" twist leade probably causes more damage to the bullet than will the shallower angle of the 12" twist. More damage to the bullet equates to more adverse effect the centrafugal force has on the bullet during flight. I'll leave it to the math garu's to figure out how much more effect the 42% more RPM may have on the centrafugal force.

As most all of the 22LR bullets I have measured run .224 - .225+ I find that not to be "incompatible" with a .224 groove barrel. Several builds of dedicated 22LR uppers I've seen built with 14" twist .224 CF barrels shoot as well as any with .222 barrels.

Back before the SF company I was full time with turned in our M16A1s (12" twist barrels) for M16A2s (7" twist barrels) we used our 50' indoor range using the M251s in the M16A1s for practice and alternate qualifications. We quickly found with the M16A2s and even a civilian 7" twist Colt H-Bars that it was difficult for Soldiers who fired expert with the M16A1s to fire a qualifying score on the same 50' target(s). We were able to retain two M16A1s in the SF company for use with the M261 22LR device for further qualifications on the indoor range at the armory. Also, given the inaccuracy with the then standard 7" twist M16A2s and M4s Big Army ceased use of the M261 devices.

Further testing at 50 yards with M16A2s and H-Bars with 7" twists further demonstrated the inaccuracy. However, using the Aguila heavier bulleted (60 gr?) subsonic 22 LR did give reasonable accuracy at 50 yards out of a 7" twist H-Bar and out of my 9" twist Colt Competition H-Bar.

[TD1886]

That's interesting. I too would figure that steeper 7 twist angle would do some damage to the soft 22LR bullet. I've love to know if the bullet didn't have that long jump to the rifling what it may have changed.

I had one of the Colt conversions. Is that same as the M261 and if so who did the Army purchase theirs from, was it Colt.

I remember shooting PMC HV 22LR ammo from mine and although not as accurate as a dedicated 22LR rifle. As I noted it was minute of squirrel easily at 25 yards. I can't remember if I shot it further. It was more of a novelty thing then a necessity. The PMC was a little bit fatter then the other 22LR ammo I had at that time. It was also copper coated, but that is such a thin coating I doubt it contributed to much.

As an aside I just recently bought some Speer 70 grain semi point bullets. Those are pretty old and Speer still makes them. I won't lie I'm not a Speer bullet fan. The only one I like way back is when that made a 150 some grain bullet in .313 diamter for the 7.65 Argentine. I believe they were the only company that produced a .313 bullet. Most were .312 or .311. It shot very well. Back to the Speer 70 grain semi point. I thought I'd shoot them from my old HBAR which had become pretty much a safe queen. I drug it out and while looking at it I though how old the style back then appeared compared to the new AR's. The lower receiver is so flat looking minus the protective ridges around the magazine release button. You know what I mean. I loaded those up with various powder burn rates and duty suprised when the old girl was wanting to shoot between 3/8's to just under 3/4 inch groups at 100 yards, velocity running 2900 fps to just making 3000 fps which is decent for that weight bullet. Not bad at all for an old 7 twist.

One of my good friends may donate me one of those old Colt conversion and I'll thoroughly test especially now that I know much more about what is going on. The one thing I definitely want to try is my 22LR bullet swage to see if the increase bullet diameter makes much difference. I'll swage them up till they barely fit, much more fatter then the fat factory one you may fine.

Thanks for replying.

[Moleman-]

Neat, I picked up one of the M261 kits back in the early 90's and occasionally plink with it usually with a 20" 1:14" mystery unmarked heavy barrel. Does fine on cans and steel targets. Never shot it for groups using 22lr though. What would cause the flat tension spring to fail? I'm using standard velocity rem or federal ammo. The original went flat pretty quick so I got a replacement. That one broke pretty quick. 3rd one seems to be fine now for 15-20 years or so. Figured I was doing something wrong. If it kept breaking them I was looking at modifying it to use a coil spring.

[TD1886]

Here's something y'all may or may not know. There is a device called a Bore Buddy that pushes your conversion unit deeper in the chamber of your rifle and takes the fore and aft play out of and supposedly making it more accurate. I haven't tried that, but if I get another conversion unit I'll make one and see if there is a difference. Here's the link and scroll down to 22LR AR Buffer pressure plug:

https://borebuddy.com/

[Larry Gibson]

Neat, I picked up one of the M261 kits back in the early 90's and occasionally plink with it usually with a 20" 1:14" mystery unmarked heavy barrel. Does fine on cans and steel targets. Never shot it for groups using 22lr though. What would cause the flat tension spring to fail? I'm using standard velocity rem or federal ammo. The original went flat pretty quick so I got a replacement. That one broke pretty quick. 3rd one seems to be fine now for 15-20 years or so. Figured I was doing something wrong. If it kept breaking them I was looking at modifying it to use a coil spring.

Interesting, I never saw a broken one. Actually, never saw any parts breakage on the devices. Shouldn't be too hard to fabricate a spring if it does happen.

[Larry Gibson]

Here's something y'all may or may not know. There is a device called a Bore Buddy that pushes your conversion unit deeper in the chamber of your rifle and takes the fore and aft play out of and supposedly making it more accurate. I haven't tried that, but if I get another conversion unit I'll make one and see if there is a difference. Here's the link and scroll down to 22LR AR Buffer pressure plug:

https://borebuddy.com/

The M261 is better designed and made than all of the commercial devices I've so far seen, including the CMMG device as shown in that site's video's. All of the problems [chamber part needing pushed forward, sloppiness of fit and gas blow back through the charger handle slot] are already addressed and are non-problems with the M261.

I would point out that at the closer ranges the use of 22LR devices in faster twist ARs the accuracy is certainly acceptable for the type of shooting demonstrated in that site's videos. However, the level of accuracy needed for 50' alternate qualification courses is just not there with 7" twist barrels as it is with 12" twist barrels. Nor did I find the accuracy to be there for small game/vermin at 50 yards as it is with the 12" twist ARs.

[Larry Gibson]

I bellieve the M261 devices were manufactured by SACO Defense, if memory serves me correctly. The Colt devices were different. The Air Force ones may have been the Colt device but it's been numerous years since I've used either the Air Force or Colt devices. They took a special magazine also. The M261 magazine inserts can be used in 20 or 30 round AR magazines and are easy to insert and take out w/o disassembly of the magazine.

Quality commercial jacketed bullets shoot fine through 7, 8 and 9" twist ARs. Never said they didn't, Not sure of the why for this "apples to oranges" comparison of quality jacketed bullets to 22LR ammunition in AR/M16s when it's not relevant?

[TD1886]

I bellieve the M261 devices were manufactured by SACO Defense, if memory serves me correctly. The Colt devices were different. The Air Force ones may have been the Colt device but it's been numerous years since I've used either the Air Force or Colt devices. They took a special magazine also. The M261 magazine inserts can be used in 20 or 30 round AR magazines and are easy to insert and take out w/o disassembly of the magazine.

Quality commercial jacketed bullets shoot fine through 7, 8 and 9" twist ARs. Never said they didn't, Not sure of the why for this "apples to oranges" comparison of quality jacketed bullets to 22LR ammunition in AR/M16s when it's not relevant?

The CMMG units in my opinion are junk. Thus why I haven't bought one. Waiting to see if my friend is going let me have the old Colt one. Today I located my 22LR bullet swage die so I'm all set to thoroughly test one again should I get one.

I only mentioned the jacketed Speer is because I never liked Speer bullet so never tried them. I was surprised they shot so good out of the old 7 twist HBAR. Remember that HBAR was old school, not free float forearml, match trigger, etc. Not a flattop either for lower scope mounting. Those free float forearms definitely increase the accuracy of an AR in my opinion.

[M-Tecs]

I bellieve the M261 devices were manufactured by SACO Defense, if memory serves me correctly. The Colt devices were different. The Air Force ones may have been the Colt device but it's been numerous years since I've used either the Air Force or Colt devices. They took a special magazine also. The M261 magazine inserts can be used in 20 or 30 round AR magazines and are easy to insert and take out w/o disassembly of the magazine.



I have three of the AF versions with 6 mags. They do take the mags pictured here plus more info and history below. The chamber inserts are rifled.

https://www.gunsinternational.com/guns-for-sale-online/parts---ammo---accessories/gun-parts----22-conversion/rare-air-force-22lr-conversion-kit-for-m16-ar15.cfm?gun_id=100489855

https://forums.g503.com/viewtopic.php?t=308557

https://www.rimfirecentral.com/threads/air-force-22-conversion-unit.1223349/

https://www.bing.com/images/search?q=air%20force%2022%20conversion%20kit&qs=n&form=QBIR&sp=-1&lq=0&pq=air%20force%2022%20conversion%20kit&sc=10-27&cvid=05F84C99F87942A48109FDD9C130640E&ghsh=0&ghacc=0&first=1

[Larry Gibson]

"Remember that HBAR was old school, not free float forearml, match trigger, etc. Not a flattop either for lower scope mounting."

Not sure where you got all that from.

The HBAR configuration matches that of the M16A2 thus it is still usable for NRA HP Service Rifle matches. The Colt HBAR I purchased in the early '90s (pre-ban) is a flat top and has worn a scope off and on since back then. I also put a float tube inside the handguards [available even back then] which free floats the barrel inside the forearm. The trigger from Colt breaks very crisply right at 4 1/4 lb, the legal lowest trigger pull for HP Competition.

When new it would hold moa for 22 shots at 200 yards [well within the X ring] with Federal 69 gr MKs. Now after numerous thousands of rounds it still holds MOA with 22 shots at 200 yards with the 69 MKs and Hornady 75 gr match bullets. That was not from a benchrest either but from a prone unsupported position w/sling. Now, since I no longer shoot HP Competition, I have replaced the fore end with a heavier aluminum tube fore end. I many use it now in suppressed mode when calling coyotes. A 55 gr Sierra Blitz King over H335 at 3100 fps still holding moa does the trick.

316429

To get back to the topic of this thread, here is the set up for use in my shooter AR15 w/12" twist milspec barrel. Been shooting this set up since '06 and it ain't broke so no need to fix it.

316430

Now, as to all the "improvements" in Leggo built ARs, I constantly see many show up at the range with ARs all "tricked out".

316431

Sorry, but that's not for this "old school" guy...........

[TD1886]

"Remember that HBAR was old school, not free float forearml, match trigger, etc. Not a flattop either for lower scope mounting."

Not sure where you got all that from.

The HBAR configuration matches that of the M16A2 thus it is still usable for NRA HP Service Rifle matches. The Colt HBAR I purchased in the early '90s (pre-ban) is a flat top and has worn a scope off and on since back then. I also put a float tube inside the handguards [available even back then] which free floats the barrel inside the forearm. The trigger from Colt breaks very crisply right at 4 1/4 lb, the legal lowest trigger pull for HP Competition.

When new it would hold moa for 22 shots at 200 yards [well within the X ring] with Federal 69 gr MKs. Now after numerous thousands of rounds it still holds MOA with 22 shots at 200 yards with the 69 MKs and Hornady 75 gr match bullets. That was not from a benchrest either but from a prone unsupported position w/sling. Now, since I no longer shoot HP Competition, I have replaced the fore end with a heavier aluminum tube fore end. I many use it now in suppressed mode when calling coyotes. A 55 gr Sierra Blitz King over H335 at 3100 fps still holding moa does the trick.

316429

To get back to the topic of this thread, here is the set up for use in my shooter AR15 w/12" twist milspec barrel. Been shooting this set up since '06 and it ain't broke so no need to fix it.

316430

Now, as to all the "improvements" in Leggo built ARs, I constantly see many show up at the range with ARs all "tricked out".

316431

Sorry, but that's not for this "old school" guy...........

Yup, everything but the kitchen sink on AR's today.

My pre ban HBAR made in early 80 wears a Japan rubber armored 3x9 Tasco and uses the COLT Marine A.R.M.S. mount on the carry handle and it's been on their since the 80'. Never taken off, transported in truck all around the country, dropped numerous time, and still ticking today. If you have a good barrel a free float tube and match trigger are the best improvement to an "old school" AR15.

I think I may have located one of the M261 conversion kits. You know how the M261 part that inserts in the chamber doesn't have the case neck section and CMMG does. Well those old Colt conversion are like the M261 in that respect. I've read where the elimination of that neck help keep from gumming the throat up. Don't know why CMMG insists on still using it and you can imagine how thin the metal is being it fits in the chamber neck area and a 22LR bullet has to pass through it.

[Larry Gibson]

Back in the '90s the issue 22LR ammo was Winchester white box match. The bullets had a generous coating of wax lube on them. One time we fired over 1k rounds through each of the two M16A1s on the armory indoor range. After about 500 rounds each the rifles began to malfunction once in a while. We found the failure to feed were caused by not making sure the mag insert was seated correctly in the magazine after loading. Failure to fully chamber malfunction was caused by the buildup of the wax lube and the normal powder fouling associated with 22LR blow back systems. A liberal application of BreakFree or LSA kept them running. I also found using copper plated 22LR ammunition greatly reduced the fouling problem. That's why I prefer the copper plated ammunition for the M261 device.

The M261 mag inserts in milsurp 20 and 30 round mags will also lock the bolt back after the last round is fired. Not sure any more about the magazines for the other devices.

[TD1886]

Larry I think another company that may have made those M261 kits was MAC Atchisson

[Larry Gibson]

The MAC Atchisson device evolved into the Atchison/Ceiner device for civilian sales. The M261 was designed by John Foote. This article is an interesting read on the 22LR devices for the M16 rifles; https://smallarmsreview.com/full-auto-rimfire-conversions-for-the-m16-rifle

A small excerpt from that article;

"John Foote, another former employee of the Military Armament Corporation, had also designed and built a .22 caliber conversion kit for the AR-15 and M16 rifle.His design competed with Atchisson’s for adoption by the U.S. Army. After the usual extensive testing and government red tape, Mr. Foote’s conversion unit won the competition and was adopted by the Army as the .22 Caliber Adapter, M261. The M261conversion was blow-back operated, with a 10-round magazine designed to fit inside a standard 20-round M16 magazine. The first production run was subcontracted out to Okay Industries, of New Britain, Connecticut. A second contract was awarded to Maremont of Saco, Maine. Mr. Foote later formed his own company, the U.S. Armament Corporation. Mr. Foote eventually sold the company and the rights to the M261 .22 caliber conversion kit."

It seems initially the M261s were manufactured by Okay Industries. There were 130,00 - 150,000 +/- of them manufactured and I do not know the breakdown of how many by which firm.

[TD1886]

The MAC Atchisson device evolved into the Atchison/Ceiner device for civilian sales. The M261 was designed by John Foote. This article is an interesting read on the 22LR devices for the M16 rifles; https://smallarmsreview.com/full-auto-rimfire-conversions-for-the-m16-rifle

A small excerpt from that article;

"John Foote, another former employee of the Military Armament Corporation, had also designed and built a .22 caliber conversion kit for the AR-15 and M16 rifle.His design competed with Atchisson’s for adoption by the U.S. Army. After the usual extensive testing and government red tape, Mr. Foote’s conversion unit won the competition and was adopted by the Army as the .22 Caliber Adapter, M261. The M261conversion was blow-back operated, with a 10-round magazine designed to fit inside a standard 20-round M16 magazine. The first production run was subcontracted out to Okay Industries, of New Britain, Connecticut. A second contract was awarded to Maremont of Saco, Maine. Mr. Foote later formed his own company, the U.S. Armament Corporation. Mr. Foote eventually sold the company and the rights to the M261 .22 caliber conversion kit."

It seems initially the M261s were manufactured by Okay Industries. There were 130,00 - 150,000 +/- of them manufactured and I do not know the breakdown of how many by which firm.

Thanks for the link.

[TD1886]

Larry I can't get that link to open in two browsers.

[Larry Gibson]

Opens right up for me.

Google "Full Auto Rimfire Conversions for the M16 Rifle" and the article site will come up.

[TD1886]

Opens right up for me.

Google "Full Auto Rimfire Conversions for the M16 Rifle" and the article site will come up.

Thanks

[TD1886]

Out of 3 browsers Chrome, Firefox, and Edge only Edge would open it. Very informative website.

[TD1886]

Ad that article talked about, did you ever manage to plug up anything in the gas system of the AR shooting those soft 22lr lead bullets? I never have. Here's another one for you the gas system. While in Nam did you ever see a plugged gas tube or carrier key?

[Larry Gibson]

No, never had nor saw any blockage in key or gas port in Viet Nam or in the years since.

Have not experienced any such with the use of the M261 device either. The manual says firing standard M193 will blow out any build up if there is any.

[TD1886]

No, never had nor saw any blockage in key or gas port in Viet Nam or in the years since.

Have not experienced any such with the use of the M261 device either. The manual says firing standard M193 will blow out any build up if there is any.

Good info Larry

[barnetmill]

Here's something y'all may or may not know. There is a device called a Bore Buddy that pushes your conversion unit deeper in the chamber of your rifle and takes the fore and aft play out of and supposedly making it more accurate. I haven't tried that, but if I get another conversion unit I'll make one and see if there is a difference. Here's the link and scroll down to 22LR AR Buffer pressure plug:

https://borebuddy.com/

Thanks for the information and I see it will work with my CMMG conversion kit. I am pleased my conversion kit. I never have had any expectation of accuracy other than hitting steel swingers at 100 ft. I use it for with an AR pistol that only has the currently legal bare buffer tube and the brace removed and disposed off. At the end of each session I fire a round of 5.56 through it to clean out the gas tube.

$52.50 – $61.50

Swap the collar on your bolt for this chamber adapter to shoot 22lr through any standard 223/556 AR. The chamber adapter is compatible with BoreBuddy/CMMG/RTB/Palmetto 22lr bolt groups.

[TD1886]

Thanks for the information and I see it will work with my CMMG conversion kit. I am pleased my conversion kit. I never have had any expectation of accuracy other than hitting steel swingers at 100 ft. I use it for with an AR pistol that only has the currently legal bare buffer tube and the brace removed and disposed off. At the end of each session I fire a round of 5.56 through it to clean out the gas tube.

$52.50 – $61.50

Swap the collar on your bolt for this chamber adapter to shoot 22lr through any standard 223/556 AR. The chamber adapter is compatible with BoreBuddy/CMMG/RTB/Palmetto 22lr bolt groups.

For what that buffer is you could make your own out of some form of plastic/nylon as it's just a spacer not a reciprocating buffer like the original when the rifle is put back into the 5.56x45 use.

[TD1886]

The M261 is better designed and made than all of the commercial devices I've so far seen, including the CMMG device as shown in that site's video's. All of the problems [chamber part needing pushed forward, sloppiness of fit and gas blow back through the charger handle slot] are already addressed and are non-problems with the M261.

I would point out that at the closer ranges the use of 22LR devices in faster twist ARs the accuracy is certainly acceptable for the type of shooting demonstrated in that site's videos. However, the level of accuracy needed for 50' alternate qualification courses is just not there with 7" twist barrels as it is with 12" twist barrels. Nor did I find the accuracy to be there for small game/vermin at 50 yards as it is with the 12" twist ARs.

I've recently noticed a similarity between the M261 and the early Colt device. That's the small flat spring at the rear of the device. That puts pressure on the unit and that is why the CMMG is sloppy because they elected to eliminate that part. CMMG makes a lot of really good things. Their Raidial Delayed Blowback bolt system is very innovative. They may have cut corners on the 22LR conversions to cut cost. When I had my Colt one I never got gas anywhere.

[barnetmill]

I've recently noticed a similarity between the M261 and the early Colt device. That's the small flat spring at the rear of the device. That puts pressure on the unit and that is why the CMMG is sloppy because they elected to eliminate that part. CMMG makes a lot of really good things. Their Raidial Delayed Blowback bolt system is very innovative. They may have cut corners on the 22LR conversions to cut cost. When I had my Colt one I never got gas anywhere.
Loose and sloppy might have other advantages relative to function or might not. But few will be used beyond plinking ranges and for me for combat training it is fine.
I would like to have a unit that would work in 300 black out or 7.62x39 uppers. The chamber would have to be extended in the 30 cal bore and be rifled.

[TD1886]

Loose and sloppy might have other advantages relative to function or might not. But few will be used beyond plinking ranges and for me for combat training it is fine.
I would like to have a unit that would work in 300 black out or 7.62x39 uppers. The chamber would have to be extended in the 30 cal bore and be rifled.

Kind of sounds like a smaller caliber device which is a steen chamber insert. Example: 32acp from a 30-06 insert. I have a 35 Whelen insert that shoot 9mm Luger. You wouldn't have to swap out your bolt, just insert the steel cartridge with the sub caliber round it. I think they your rifle becomes a single shot.

[barnetmill]

Kind of sounds like a smaller caliber device which is a steen chamber insert. Example: 32acp from a 30-06 insert. I have a 35 Whelen insert that shoot 9mm Luger. You wouldn't have to swap out your bolt, just insert the steel cartridge with the sub caliber round it. I think they your rifle becomes a single shot.

A single shot is not much good for combat training is the problem. But one can shoot for example 9mm in .410. So why not a cmmg chamber insert with rifling to allow use of .22 in a 300 bore rifle. Perhaps the rifled extension would not have enough wall thickness to be useful.

https://cdn1.bigcommerce.com/server1700/37586/products/90/images/1004/410_to_9mm_Luger_copy__42226.1688420515.500.659.PN G?c=2

[Larry Gibson]

https://www.youtube.com/watch?v=oXVXON95buM

Here's an accuracy test of various ammo with the CMMG Bravo device in a Ruger AR with an 8" twist custom barrel.

[Moleman-]

Interesting shooting results. At 50yds out of the 1:14" barrel it's easy to hit cans. May have to take it to the range next time and actually shoot on paper. No issues with the gas system either. I used to only run a chamber brush and bore brush through the barrel before switching to 223 if I've shot more than a box. One time I made the switch with it pretty dirty and the first round fired but stuck in the chamber. The rim was ripped off and the extractor pin bent. I keep a cleaning kit in the truck and have a spare extractor with spring and pin in my range box. Knocked the case out, replaced the extractor and pin, gave it a quick cleaning and it ran trouble free in 223 like normal. Just a fluke? Don't know but I make sure to run the chamber and bore brush though it every time now when switching back to 223.

[TD1886]

https://www.youtube.com/watch?v=oXVXON95buM

Here's an accuracy test of various ammo with the CMMG Bravo device in a Ruger AR with an 8" twist custom barrel.

I watched that. Here's what I got from it. When he was using the device with 22LR it shot the best with those 36 gr hollow points. If I had all the bullets he shot and could compare the bullet length, not the OAL, be interesting if seeing that the 36 gr bullet is shorter or not. If so, according to twist theorist, the shorter bullet should have shot the worse because of the too much twist for it. I didn't count the Stinger round becasue it's altogether a whole different thing then the standard Long Rifles and the velocity is much higher. I have had Stingers shoot exceptionally accurate in regular 22 LR rifles and pistol/revolvers. I'd have to say the CMMG device shot crappy. Looking at it out of the rifle is certainly looks very well made. I'm going to have either an older Colt device or a M261 device coming soon so I'll do a thurough test.

[Larry Gibson]

I was mildly surprised by the MiniMag group he got. That is until he said at the end, he said he had the custom 8" twist barrel on the Ruger AR. That made a bit more sense as his MiniMag group closely resembles the same size of groups my 9" twist Colt HBar with most HV 36 gr copper plated 22LRs that have been "Waltzed". The Colt's 50 yard 10 shot groups usually run 2"+ with a couple filers. The RPM using most "HV" 36 gr HPs with 8 and 9" twist barrels will run 100,000 to 113,000+/-.

I've got some MiniMag stashed away with other 22LR loads including some Rem Yellow Jacket, Stingers and some subsonic. If the weather cools a bit I'll also get out and run a test through my 12" twist milsurp barreled AR.

[TD1886]

I was mildly surprised by the MiniMag group he got. That is until he said at the end, he said he had the custom 8" twist barrel on the Ruger AR. That made a bit more sense as his MiniMag group closely resembles the same size of groups my 9" twist Colt HBar with most HV 36 gr copper plated 22LRs that have been "Waltzed". The Colt's 50 yard 10 shot groups usually run 2"+ with a couple filers. The RPM using most "HV" 36 gr HPs with 8 and 9" twist barrels will run 100,000 to 113,000+/-.

I've got some MiniMag stashed away with other 22LR loads including some Rem Yellow Jacket, Stingers and some subsonic. If the weather cools a bit I'll also get out and run a test through my 12" twist milsurp barreled AR.

When I get those devices I'll do a test. This will be with my old HBAR. I'm worried the gas port hole is large and might tear up those soft 22lr's. I have a 16 inch barrel carbine that's new. Might try it also and it's a 7 twist too. I want to get to the bottom of is it the twist or the over sized 5.56 barrel for the 22LR.

[TD1886]

So what could a custom barrel entail? It's still more then likely going to be a .224 bore and still be a 7 twist. Probably not chromed lined too.

[Larry Gibson]

Noting almost [at least I've not found any other twists] all dedicated AR 22LR uppers and replacement barrels have 14 or 16" twists. Hard to find any groove specifications for those barrels but I'm assuming they are the standard .222/.223 of regular 22LR barrels. You may have something on the barrel groove diameter affecting accuracy but the bullets in the video targets all went through point first demonstrating the bullets were sufficiently stabilized.

My previous testing Back in the early 'mid/late 80s using multiple military M16As (12" twist), M16A2s (7" twists) and commercial AR HBars (9" twist) showed definitely the 12" twists always gave better accuracy. That's why back in '06 when I found a new military contract refinished M16 upper with a new milpsec made M16A1 barrel I bought it immediately and built my AR "shooter" for use with M193 and Speer 52 gr HP reloads along with the usefulness of the M261 device.

The shooter in the video states at the end of the video that the Ruger barrel is a 16" factory barrel with an 8" twist. I must not have had my "ears" in when I first watched it and "heard" custom and assumed it was as I didn't know Ruger was useing 8" twist barrels as they are mostly used for competition rifles. Not on 16" M4 wanna be's. He also wonders if the inaccuracy, particularly with the higher velocity loads, has something to do with the fast twist. He's right, it does.

[rockrat]

IIRC, H&K had a 22 cal. conversion kit for their HK91/G3 rifles that had a barrel that fit down the 30 cal. bore. I just use a dedicated 22lr upper I got years ago.

[M-Tecs]

I understand why the AR15 22LR Conversion Kits came about for military usage and early AR 15 civilian usage. In the 80's and early 90's I had to qualify with them. I didn't care for them then and I still don't care for them now.

I did liberate 3 AF M-261's when the AF discontinued usage. I have mine paired with 3 retro builds I did but I rarely shoot they. I do have several dedicated 22 LR uppers that I love. I built a couple of Krieger barreled dedicated 22LR uppers that will give the best match rifles a run for their money.

What I don't understand is why folks spend $169 or more on a conversion kit when you can purchase a dedicated 22 LR upper for around $50 more?

https://www.bearcreekarsenal.com/22-long-16-parkerized-barrel-1-16-twist-15-mlok-scg2-nrail-branded.html

[TD1886]

I understand why the AR15 22LR Conversion Kits came about for military usage and early AR 15 civilian usage. In the 80's and early 90's I had to qualify with them. I didn't care for them then and I still don't care for them now.

I did liberate 3 AF M-261's when the AF discontinued usage. I have mine paired with 3 retro builds I did but I rarely shoot they. I do have several dedicated 22 LR uppers that I love. I built a couple of Krieger barreled dedicated 22LR uppers that will give the best match rifles for the money.

What I don't understand is why folks spend $169 or more on a conversion kit when you can purchase a dedicated 22 LR upper for around $50 more?

https://www.bearcreekarsenal.com/22-long-16-parkerized-barrel-1-16-twist-15-mlok-scg2-nrail-branded.html

When I bought my one and only first Colt unit I don't believe there were any dedicated uppers being made. It was just the idea of a novelty I believe.

Just recently I build a dedicated 22 Magnum upper. I've always felt and believe 22 mags weren't as accurate as 22LR rifles because the manufactured wouldn't do all the tricks to improve their accuracy. One which is a more match type chamber. So my match heavy barrel (Green Mountain 22 Mag barrel specifically made for the 22 Mag) AR15 with a special reamer I got made shoots very very small one hole groups at 100 yards. Then after I bought a Howa 22 Mag rifle, bolt action, and to my surprise it does the same thing. After that I bought an old Winchester 22 LR bolt rifle, one of the very few that Winchester made with a two front locking lug bolt with control feed. Forget the model number off the top of my head. I pulled the barrel and used my special 22 Mag reamer and put it back together as a single shot. Scoped it and with the stock trigger, standard 22LR barrel, and a 22LR bore and groove the .224 22 Mag bullet shot very well indeed. Not like the other two for sure, but let's say 1/2 inch at 100 yards. A lot of times I do things just to do them if you're wondering.

[TD1886]

Noting almost [at least I've not found any other twists] all dedicated AR 22LR uppers and replacement barrels have 14 or 16" twists. Hard to find any groove specifications for those barrels but I'm assuming they are the standard .222/.223 of regular 22LR barrels. You may have something on the barrel groove diameter affecting accuracy but the bullets in the video targets all went through point first demonstrating the bullets were sufficiently stabilized.

My previous testing Back in the early 'mid/late 80s using multiple military M16As (12" twist), M16A2s (7" twists) and commercial AR HBars (9" twist) showed definitely the 12" twists always gave better accuracy. That's why back in '06 when I found a new military contract refinished M16 upper with a new milpsec made M16A1 barrel I bought it immediately and built my AR "shooter" for use with M193 and Speer 52 gr HP reloads along with the usefulness of the M261 device.

The shooter in the video states at the end of the video that the Ruger barrel is a 16" factory barrel with an 8" twist. I must not have had my "ears" in when I first watched it and "heard" custom and assumed it was as I didn't know Ruger was useing 8" twist barrels as they are mostly used for competition rifles. Not on 16" M4 wanna be's. He also wonders if the inaccuracy, particularly with the higher velocity loads, has something to do with the fast twist. He's right, it does.

Well I'm going to try find out if he was right. I got some tricks to try. I think his CMMG unit may have been a little more accurate if it fit tighter or maybe if it that buffer spacer which keeps it pressed forward tighter. That may or may not stopped the gas blow back in the charging handle channel as the shoulder of the adapter would be pressed more to keep it's datum line up against the datum line of the chamber for a better gas seal.

[Outpost75]

Limited experience with M261 here. My reserve unit in 1980s had a dozen by Saco Defense which armorers mated up with older M16A1 uppers with 12" twist barrels. They shot acceptably for training purposes indoors at 25 yards with the Winchester white box ammo being issued. I had an opportunity to buy one, but firing outdoors at 100 yards with my 9" twist CMG2 barrel on Colt HBAR I was not impressed and passed.

[barnetmill]

I understand why the AR15 22LR Conversion Kits came about for military usage and early AR 15 civilian usage. In the 80's and early 90's I had to qualify with them. I didn't care for them then and I still don't care for them now.

I did liberate 3 AF M-261's when the AF discontinued usage. I have mine paired with 3 retro builds I did but I rarely shoot they. I do have several dedicated 22 LR uppers that I love. I built a couple of Krieger barreled dedicated 22LR uppers that will give the best match rifles for the money.

What I don't understand is why folks spend $169 or more on a conversion kit when you can purchase a dedicated 22 LR upper for around $50 more?

https://www.bearcreekarsenal.com/22-long-16-parkerized-barrel-1-16-twist-15-mlok-scg2-nrail-branded.html
my reason for the conversion is the trigger and sighting arrangement are identical since an AR pistol more of closer range combat weapon. 100 ft is my max .22 training range for now. If I want shoot further I will have to use 5.56.
Since it being used with rimfire full strength springs are required for the trigger - hammer group. Buy a dedicated upper and you need a new optic. The ATF forbids iron sights or fixed focus scopes on AR pistols.

[TD1886]

my reason for the conversion is the trigger and sighting arrangement are identical since an AR pistol more of closer range combat weapon. 100 ft is my max .22 training range for now. If I want shoot further I will have to use 5.56.
Since it being used with rimfire full strength springs are required for the trigger - hammer group. Buy a dedicated upper and you need a new optic. The ATF forbids iron sights or fixed focus scopes on AR pistols.

Good post

[M-Tecs]

my reason for the conversion is the trigger and sighting arrangement are identical since an AR pistol more of closer range combat weapon. 100 ft is my max .22 training range for now. If I want shoot further I will have to use 5.56.
Since it being used with rimfire full strength springs are required for the trigger - hammer group. Buy a dedicated upper and you need a new optic. The ATF forbids iron sights or fixed focus scopes on AR pistols.

????????????????????????

https://www.guns.com/firearms/handguns/semi-auto/heckler-&-koch-hk416-22-lr-semi-automatic-20-rounds-8-5-barrel-new?p=866896

https://www.impactguns.com/semi-auto-handguns/hk-416-pistol-22-lr-8-5-barrel-20rd-matte-black-642230257894-81000403

https://www.deltateamtactical.com/journeyman-75-ar-15-556-nato-complete-pistol.html

https://palmettostatearmory.com/psa-10-5-carbine-length-5-56-nato-1-7-phosphate-12-m-lok-moe-ept-sba3-pistol-kit-with-mbus-sight-set-romeo-msr.html

https://palmettostatearmory.com/psa-10-5-5-56-nato-1-7-nitride-classic-mft-battlink-pistol-kit.html

https://palmettostatearmory.com/psa-10-5-5-56-nato-1-7-phosphate-classic-shockwave-pistol-kit-black-51654489732.html

https://moriartiarmaments.com/pistol-kits/ar-15-5.56.223-10.5-ultralight-honeycomb-series-pistol-kit-clear-trident-pistolkit-air-clear-10

https://www.impactguns.com/Semi-Auto-Handguns/Century-Micro-Draco-Semi-Auto-Pistol-6-Barrel-1X30rd-Mag-787450232792-HG2797-N/

Pistols with a brace using a sighting system that requires shouldering the brace to use did/does change the classification to a SBR since that show intent to shoulder per the ATF.

As to the ATF forbidding iron sights or fixed focus scopes on AR pistols please site your source? Seems place like lots of manufactures/retailers are breaking the law?????

[TD1886]

????????????????????????

https://www.guns.com/firearms/handguns/semi-auto/heckler-&-koch-hk416-22-lr-semi-automatic-20-rounds-8-5-barrel-new?p=866896

https://www.impactguns.com/semi-auto-handguns/hk-416-pistol-22-lr-8-5-barrel-20rd-matte-black-642230257894-81000403

https://www.deltateamtactical.com/journeyman-75-ar-15-556-nato-complete-pistol.html

https://palmettostatearmory.com/psa-10-5-carbine-length-5-56-nato-1-7-phosphate-12-m-lok-moe-ept-sba3-pistol-kit-with-mbus-sight-set-romeo-msr.html

https://palmettostatearmory.com/psa-10-5-5-56-nato-1-7-nitride-classic-mft-battlink-pistol-kit.html

https://palmettostatearmory.com/psa-10-5-5-56-nato-1-7-phosphate-classic-shockwave-pistol-kit-black-51654489732.html

https://moriartiarmaments.com/pistol-kits/ar-15-5.56.223-10.5-ultralight-honeycomb-series-pistol-kit-clear-trident-pistolkit-air-clear-10

https://www.impactguns.com/Semi-Auto-Handguns/Century-Micro-Draco-Semi-Auto-Pistol-6-Barrel-1X30rd-Mag-787450232792-HG2797-N/

Pistols with a brace using a sighting system that requires shouldering the brace to use did/does change the classification to a SBR since that show intent to shoulder per the ATF.

As to the ATF forbidding iron sights or fixed focus scopes on AR pistols please site your source? Seems place like lots of manufactures/retailers are breaking the law?????

From the way I understand it if you mount a scope on an AR pistol that is a "rifle scope" which is determined by: (iii) whether the weapon is equipped with sights or a scope with eye relief that require the weapon to be fired from the
shoulder in order to be used as designed;

Here's the link:

https://www.atf.gov/rules-and-regulations/docs/undefined/finalrule2021r-08f508pdf/download

I believe doing this in the beginning is where they (the manufacturers) got into trouble with the SBR/AR Pistols. If if you don't put a shouldering device on it, it's the "intent" that makes it illegal.

[M-Tecs]

From the way I understand it if you mount a scope on an AR pistol that is a "rifle scope" which is determined by: (iii) whether the weapon is equipped with sights or a scope with eye relief that require the weapon to be fired from the
shoulder in order to be used as designed;

Here's the link:

https://www.atf.gov/rules-and-regulations/docs/undefined/finalrule2021r-08f508pdf/download

I believe doing this in the beginning is where they (the manufacturers) got into trouble with the SBR/AR Pistols. If if you don't put a shouldering device on it, it's the "intent" that makes it illegal.

That is my understanding also and that is 180% opposite of the claim that "The ATF forbids iron sights or fixed focus scopes on AR pistols".

[TD1886]

That is my understanding also and that is 180% opposite of the claim that "The ATF forbids iron sights or fixed focus scopes on AR pistols".

I agree the iron sights is incorrect. Let's clear up what you or they mean by a fixed scope. All I'll say is that if a scope is a rifle scope by very short eye relief whether is a fixed power or variable is in violation.

It my opinion that the ATF (and whoever else is in all this that are anti gun) deliberatly made it all confusing to trip us up.

[M-Tecs]

I agree the iron sights is incorrect. Let's clear up what you or they mean by a fixed scope. All I'll say is that if a scope is a rifle scope by very short eye relief whether is a fixed power or variable is in violation.

It my opinion that the ATF (and whoever else is in all this that are anti gun) deliberatly made it all confusing to trip us up.

Per the ATF

(iii) whether the weapon is equipped with sights or a scope with eye
relief that require the weapon to be fired from the shoulder in
order to be used as designed;
 Sights or scopes that cannot be used without shouldering the
weapon indicates that the firearm is designed and intended to be
fired from the shoulder

[TD1886]

Per the ATF

(iii) whether the weapon is equipped with sights or a scope with eye
relief that require the weapon to be fired from the shoulder in
order to be used as designed;
 Sights or scopes that cannot be used without shouldering the
weapon indicates that the firearm is designed and intended to be
fired from the shoulder


Well of courser per the ATF. They think then can legislate laws and inact them.

[M-Tecs]

From the way I understand it if you mount a scope on an AR pistol that is a "rifle scope" which is determined by: (iii) whether the weapon is equipped with sights or a scope with eye relief that require the weapon to be fired from the
shoulder in order to be used as designed;

Here's the link:

https://www.atf.gov/rules-and-regulations/docs/undefined/finalrule2021r-08f508pdf/download

I believe doing this in the beginning is where they (the manufacturers) got into trouble with the SBR/AR Pistols. If if you don't put a shouldering device on it, it's the "intent" that makes it illegal.

You can put what eye-relief scope you want on any handgun as long as it DOES NOT have a brace. That is where the "intent" comes in. Can't have "intent" to shoot it from the shoulder if it cannot be fired from the shoulder. The long range handgunners do it all the time on their single shot and bolt action handguns and its 100% legal.

[Digital Dan]

Larry Gibson's comments about bullet diameter very early in this discussion sparked a little curiosity and I just measured a few from my stockpile.

CCI .22 CB Short, vintage 2000-2010 = .225"
Wolf MT and SK Standard +, vintage 2015-2020 = .223"
Remington .22 Long, vintage estimated at 1980-1990 = .222"
WW .22 Short, vintage estimated at 1980-1990 = .222"
WW PP .22 LR, vintage 2000 = .223"

I shoot the CB Shorts in a Contender Carbine w/match chamber and it shoots 5 shot one-hole groups at 25 yards

WW PP are used in a 10/22 manufactured in 1971 w/full length bedding. One hole groups of 5 at 50 yards, and one group of three fired at 100 yards of .436". It is my preferred ammo for the 10/22.

Wolf MT/SK is fired in a variety of rifles and is in fact my go to round for all. T/C Carbine (match barrel), Rem 513 S&T etc. All shoot the ammo quite well. My best 50 yard group with Contender was .091".

[TD1886]

Larry Gibson's comments about bullet diameter very early in this discussion sparked a little curiosity and I just measured a few from my stockpile.

CCI .22 CB Short, vintage 2000-2010 = .225"
Wolf MT and SK Standard +, vintage 2015-2020 = .223"
Remington .22 Long, vintage estimated at 1980-1990 = .222"
WW .22 Short, vintage estimated at 1980-1990 = .222"
WW PP .22 LR, vintage 2000 = .223"

I shoot the CB Shorts in a Contender Carbine w/match chamber and it shoots 5 shot one-hole groups at 25 yards

WW PP are used in a 10/22 manufactured in 1971 w/full length bedding. One groups of 5 at 50 yards, and one group of three fired at 100 yards of .436". It is my preferred ammo for the 10/22.

Wolf MT/SK is fired in a variety of rifles and is in fact my go to round for all. T/C Carbine (match barrel), Rem 513 S&T etc. All shoot the ammo quite well. My best 50 yard group with Contender was .091".

If you go back and look I mentioned the diameter of the 22lr bullet first and in fact the reason I started this thread with Larry Gibson. Here's one line from that first post: " What is your opinion that destroys the accuracy in the 7 twist, the incompadible diameter of the 22LR bullet to the .224 groove, the rpm of the bullet, or the fast twist is somehow ruining the very soft bullet to cause it be inaccurate." It has to be one of the reason of the inaccuracy.

[Digital Dan]

https://saami.org/wp-content/uploads/2022/08/ANSI-SAAMI-Z299.1-Rimfire-2018-Approved-2018-06-13.pdf

Scroll down about 14 pages or so.

[TD1886]

You can put what eye-relief scope you want on any handgun as long as it DOES NOT have a brace. That is where the "intent" comes in. Can't have "intent" to shoot it from the shoulder if it cannot be fired from the shoulder. The long range handgunners do it all the time on their single shot and bolt action handguns and its 100% legal.

You'll see I mentioned that in what you quoted, that is with the brace. What got the manufacturer in trouble is they submitted the that firearm without a scope to the ATF. The ATF approved it. After it was approved the company put advertisements out with the approved firearm with a "rifle scope" and that's when the poop hit the fan with the ATF. A friend of mine involved this this said that if the company would have submitted the firearm with a rifle scope on it the story would have been different. We both think the ATF wouldn't have approved it. It is my believe that the "brace" was first intended to help steady the firearm. Then the ATF started complaining. Then some smart people on the side of the braces came up with it was meant for handicapped people. Known fact when some legal procedure involves handicapped people the law kind of favors them.

Maybe we can start a new thread on this as it would be nice to stick to the topic of this thread which is the 22lr conversion units for the AR15. Notice, so you don't get twisted in a knot, that I'm not telling you or anyone else what to do as we've had that discussion before, okay?

[Larry Gibson]

To add to Digital Dan's list (post #52);

Measured some unswaged 22LR bullets this morning with a micrometer. I noticed a large number of the cartridges were not symmetrical round giving a variation of up to .0015 in measurement of the same bullet. Of course lot to lot variation in bullet diameter will probably occur.

Lapua Midas+ .2245
Win Pistol Match .2225
CCI CB Longs .2235
Fed Amer Eagle .2245*
Fed Champion .223- 2253
CCI Blazer .2235
Win Match .2245
CCI Target .224
Rem Golden .224*
CCI MiniMag .2225*
CCI Velocitor .223
Armscorp HV HP .224*
CCI Stinger .2245
Wolf Match Target .224
CCI Segmented .224
CCI Subsonic 45 HP .2255

“*” are those I swaged to .225 with the Waltz die and primarily use in the 12” twist AR w/M261 device. I also use the Winchester HV HP copper plated bulk but did not have any unswaged to measure.

[Larry Gibson]

If you go back and look I mentioned the diameter of the 22lr bullet first and in fact the reason I started this thread with Larry Gibson. Here's one line from that first post: " What is your opinion that destroys the accuracy in the 7 twist, the incompadible diameter of the 22LR bullet to the .224 groove, the rpm of the bullet, or the fast twist is somehow ruining the very soft bullet to cause it be inaccurate." It has to be one of the reason of the inaccuracy.

As I've mentioned several times, with my previous testing of various AR/M16s with common .23/5.56 barrels with .224 groove of 7, 9 and 12" twist the inaccuracy of the faster twist barrels is caused by the faster RPMs greater centrafugal force on the bullets. Also, the bullets may be getting damaged more by the sharper leade angles of the faster twist. If the bullets are damaged more [you would have to trap some out of each twist to know for sure] but suffice to say any damage that unbalances the bullet would give the increased centrifugal force of the faster twist [because they have higher RPM given the same velocity] more to act on.

It may be a combination of all three reasons. However, swaging the bullets to a uniform .225 should negate the .224 barrel reason. Remains to be seen though through additional testing.

[TD1886]

As I've mentioned several times, with my previous testing of various AR/M16s with common .23/5.56 barrels with .224 groove of 7, 9 and 12" twist the inaccuracy of the faster twist barrels is caused by the faster RPMs greater centrafugal force on the bullets. Also, the bullets may be getting damaged more by the sharper leade angles of the faster twist. If the bullets are damaged more [you would have to trap some out of each twist to know for sure] but suffice to say any damage that unbalances the bullet would give the increased centrifugal force of the faster twist [because they have higher RPM given the same velocity] more to act on.

It may be a combination of all three reasons. However, swaging the bullets to a uniform .225 should negate the .224 barrel reason. Remains to be seen though through additional testing.

That's exactly what I intend to do Larry is swage the bullets. When you did that did you notice any increase at all in accuracy? What I'm going to do is with the unit out of the rifle I'm going to keep swaging up the diameter until I reach the maximum that will fit the chamber. I may even swage far enough up to where I have to hand insert them. I definitely want to see what a fatter bullet will do.

[Larry Gibson]

"That's exactly what I intend to do Larry is swage the bullets. When you did that did you notice any increase at all in accuracy?"

Never actually tested the difference. When I got the M261 device back in '06 I already had the Paco and Litz dies so I just arbitrarily swaged the rounds to uniform them at .225 and to improve the HP opening for greater lethality. I shot a few them in my 9" twist Colt HBar but not many as I really was looking for a 12" twist M16A1 barrel. Wasn't until '08 I got found the 12" twist M16 upper with the new milspec M16A1 barrel. As mentioned, I have just arbitrarily swaged the 22LR ammo for it.

Previous shooting back in the early '90s with M16A1s, M16A2s and HBars had been done at 50' and 50 yards with out of the box 22LR ammo.

I'll be testing some different ammo makes/types both swaged and out of the box as soon as it cools a bit.

[TD1886]

"That's exactly what I intend to do Larry is swage the bullets. When you did that did you notice any increase at all in accuracy?"

Never actually tested the difference. When I got the M261 device back in '06 I already had the Paco and Litz dies so I just arbitrarily swaged the rounds to uniform them at .225 and to improve the HP opening for greater lethality. I shot a few them in my 9" twist Colt HBar but not many as I really was looking for a 12" twist M16A1 barrel. Wasn't until '08 I got found the 12" twist M16 upper with the new milspec M16A1 barrel. As mentioned, I have just arbitrarily swaged the 22LR ammo for it.

Previous shooting back in the early '90s with M16A1s, M16A2s and HBars had been done at 50' and 50 yards with out of the box 22LR ammo.

I'll be testing some different ammo makes/types both swaged and out of the box as soon as it cools a bit.

Okay thanks Larry. I'll do the testing, if I can, and we will see what the difference is. BTW it's going to be an early COLT unit which is very close to the M261, definitely not the CMMG. I wouldn't have the CMMG. Stay tuned the unit arrives next week sometime and then I have to get to it when I have time.

Pretty good thread so far don't you think?

[Larry Gibson]

It's been a very good discussion.

[TD1886]

Okay Mr Larry Gibson, this is kind of the test you and I have been waiting for. I got the Colt unit today, was suppose to be here yesterday, but we had some really horrible thunderstorms that resulted in trees down and a power outage of 10 hours for me. So here is what I did. I tested at 25 yards just to see what I'm going to be working with. I won't lie the results at that distance weren't very gratifying. So then I started swaging the 22's. I had the unit out and it's has a generous chamber and accepted my swaged ammo A Okay. Let me remark at this point the Colt unit appears to be very much a copy of the military M261 except for one thing, the magazine. Colt supplied a decaded magazine. Back to the test. The swaged bullets reduced the groups by 50% or so. Still not what I was looking at. I checked out some things on the unit and saw what I thought all along might be the accuracy problem. I'm not going to mention here (sorry guys) because it is a permanent modification to the unit and requires tools that most people won't have. So I done that and went out again at 25 yards with the swaged bullet. VIOLA!! The group improved by almost a 100%. It shot a raggy butt hole at 25 yards, say in the order of smaller then 1/2 inch easy. Very very encouraging so now to test at a further distance and not with one brand of ammo, but various 22 ammo I have. BTW that initial test ammo was PMC. I hope the old 7 twist HBAR holds up to some useable accaracy at further distance.

[barnetmill]

You can put what eye-relief scope you want on any handgun as long as it DOES NOT have a brace. That is where the "intent" comes in. Can't have "intent" to shoot it from the shoulder if it cannot be fired from the shoulder. The long range handgunners do it all the time on their single shot and bolt action handguns and its 100% legal.

I have been out of town. In my earlier comment I should have said brace, but still on an AR15 pistol that still has a buffer tube, I still would not put a fixed focus scope. Especially if it is 7.125 length tube that is the carbine length buffer. ATF says that the 7.125 inch length is ok for a legal pistol, but it is still possible for some people to shoulder such a bare buffer tube. The ATF says 6.5 inches is a pistol buffer length, but their discussion on cost impacts of their ruling said that the 7.125 tube was ok and did not need to be changed.
I have no idea what they would say if there was a fixed focus scope on the carbine length buffer tube on such a pistol since that means someone is planning to use the buffer tube for shouldering in their minds.
But it really looks like ATF is going be defeated on the ruling on administrative causes if nothing else.
So maybe I am making much ado about what will be nothing.

[M-Tecs]

Most of my handgun scopes are fixed focus scopes even if they are extended eye relief. Being a fixed focus scope is not the issue. Focus length and eye relief are not the same.

Eye relief can become an issue if the short eye relief does not allow the pistol from being fired unless the brace is likely to be touching the shoulder per the ATF. Cheek rests extensions are still considered legal. That is where the “intent” gets to be an issue. If you can’t see thru the scope without the brace likely touching your shoulder intent is established per the ATF. If you can’t use the brace as designed as a wrist support due not being able to sight thru the scope due to short eye relief how are you intending to use it?

I don’t agree with the ATF but they have the legal authority for prosecute you if you go against their regulations.

An AR15 pistol with a brace using an extended eye relief scope is fine in the areas where braces are currently legal. Just don’t get caught shouldering it. At one time the ATF stated if was legal to shoulder the Sig brace. That has been rescinded.

The issue is ability to shoulder it when the barrel is less than 16". Contenders, Encores and AR pistols with braces become short barrel rifles when shouldered with a barrel of less than 16" per the ATF's definition.

A normal handgun is basically impossible to fire from the shoulder. Contenders, Encore and various other handguns are commonly and legally scoped with "rifle" scopes and shot from rests or bipods. Since they can't be shouldered it's not a legal issue nor is there any possibility for using it as a short barreled rife when the pistol grip is installed.

There is nothing in the legal definition of SBR that specifically involves your intent or how you actually use it. The legal definition is just a physical description of the firearm itself.

2.1.3 Rifle. A rifle is a firearm designed to be fired from the shoulder and designed to use the energy of an explosive in a fixed cartridge to fire only a single projectile through a rifled barrel for each single pull of the trigger.11 A rifle subject to the NFA has a barrel or barrels of less than 16 inches in length.
NFA Handbook - Appendix A (atf.gov)

The law 26 U.S.C. 5845(c):
(c) Rifle. The term 'rifle' means a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder and designed or redesigned and made or remade to use the energy of the explosive in a fixed cartridge to fire only a single projectile through a rifled bore for each single pull of the trigger, and shall include any such weapon which may be readily restored to fire a fixed cartridge.
https://www.atf.gov/file/58141/download

The ATF's NFA Handbook:
2.1.3 Rifle. A rifle is a firearm designed to be fired from the shoulder and designed to use the energy of an explosive in a fixed cartridge to fire only a single projectile through a rifled barrel for each single pull of the trigger. A rifle subject to the NFA has a barrel or barrels of less than 16 inches in length. The ATF procedure for measuring barrel length is to measure from the closed bolt (or breech-face) to the furthermost end of the barrel or permanently attached muzzle device. Permanent methods of attachment include full-fusion gas or electric steel-seam welding, high-temperature (1100°F) silver soldering, or blind pinning with the pin head welded over. Barrels are measured by inserting a dowel rod into the barrel until the rod stops against the bolt or breech-face. The rod is then marked at the furthermost end of the barrel or permanently attached muzzle device, withdrawn from the barrel, and measured.

https://www.atf.gov/firearms/docs/atf-national-firearms-act-handbook-chapter-2/download

Gun Control Act Definitions
Pistol
18 U.S.C., § 921(A)(29) and 27 CFR § 478.11
The term “Pistol” means a weapon originally designed, made, and intended to fire a projectile (bullet) from one or more barrels when held in one hand, and having:
• a chamber(s) as an integral part(s) of, or permanently aligned with, the bore(s);
• and a short stock designed to be gripped by one hand at an angle to and extending below the line of the bore(s).
Firearms - Guides - Importation & Verification of Firearms - Gun Control Act Definition - Pistol | Bureau of Alcohol, Tobacco, Firearms and Explosives (atf.gov)

[barnetmill]

Most of my handgun scopes are fixed focus scopes even if they are extended eye relief. Being a fixed focus scope is not the issue. Focus length and eye relief are not the same.

Eye relief can become an issue if the short eye relief does not allow the pistol from being fired unless the brace is likely to be touching the shoulder per the ATF. Cheek rests extensions are still considered legal. That is where the “intent” gets to be an issue. If you can’t see thru the scope without the brace likely touching your shoulder intent is established per the ATF. If you can’t use the brace as designed as a wrist support due not being able to sight thru the scope due to short eye relief how are you intending to use it?

I don’t agree with the ATF but they have the legal authority for prosecute you if you go against their regulations.

An AR15 pistol with a brace using an extended eye relief scope is fine in the areas where braces are currently legal. Just don’t get caught shouldering it. At one time the ATF stated if was legal to shoulder the Sig brace. That has been rescinded.

The issue is ability to shoulder it when the barrel is less than 16". Contenders, Encores and AR pistols with braces become short barrel rifles when shouldered with a barrel of less than 16" per the ATF's definition.

A normal handgun is basically impossible to fire from the shoulder. Contenders, Encore and various other handguns are commonly and legally scoped with "rifle" scopes and shot from rests or bipods. Since they can't be shouldered it's not a legal issue nor is there any possibility for using it as a short barreled rife when the pistol grip is installed.

There is nothing in the legal definition of SBR that specifically involves your intent or how you actually use it. The legal definition is just a physical description of the firearm itself.

2.1.3 Rifle. A rifle is a firearm designed to be fired from the shoulder and designed to use the energy of an explosive in a fixed cartridge to fire only a single projectile through a rifled barrel for each single pull of the trigger.11 A rifle subject to the NFA has a barrel or barrels of less than 16 inches in length.
NFA Handbook - Appendix A (atf.gov)

The law 26 U.S.C. 5845(c):
(c) Rifle. The term 'rifle' means a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder and designed or redesigned and made or remade to use the energy of the explosive in a fixed cartridge to fire only a single projectile through a rifled bore for each single pull of the trigger, and shall include any such weapon which may be readily restored to fire a fixed cartridge.
https://www.atf.gov/file/58141/download

The ATF's NFA Handbook:
2.1.3 Rifle. A rifle is a firearm designed to be fired from the shoulder and designed to use the energy of an explosive in a fixed cartridge to fire only a single projectile through a rifled barrel for each single pull of the trigger. A rifle subject to the NFA has a barrel or barrels of less than 16 inches in length. The ATF procedure for measuring barrel length is to measure from the closed bolt (or breech-face) to the furthermost end of the barrel or permanently attached muzzle device. Permanent methods of attachment include full-fusion gas or electric steel-seam welding, high-temperature (1100°F) silver soldering, or blind pinning with the pin head welded over. Barrels are measured by inserting a dowel rod into the barrel until the rod stops against the bolt or breech-face. The rod is then marked at the furthermost end of the barrel or permanently attached muzzle device, withdrawn from the barrel, and measured.

https://www.atf.gov/firearms/docs/atf-national-firearms-act-handbook-chapter-2/download

Gun Control Act Definitions
Pistol
18 U.S.C., § 921(A)(29) and 27 CFR § 478.11
The term “Pistol” means a weapon originally designed, made, and intended to fire a projectile (bullet) from one or more barrels when held in one hand, and having:
• a chamber(s) as an integral part(s) of, or permanently aligned with, the bore(s);
• and a short stock designed to be gripped by one hand at an angle to and extending below the line of the bore(s).
Firearms - Guides - Importation & Verification of Firearms - Gun Control Act Definition - Pistol | Bureau of Alcohol, Tobacco, Firearms and Explosives (atf.gov)

You did not consider what I posted and this is dealing with no brace on an AR15 pistol with a buffer tube long enough that according to ATF can be shouldered via the buffer tube. A bare buffer tube can be shouldered. You put a short eye relief optic on the gun this could show intent on the part of the ATF that you will be shouldering the AR pistol and get you in hot water.
Be very careful about saying something is legal. Me while I am saying something could be illegal, if I am wrong no one goes to jail; telling someone that the ATF will not go after them can have horrendous consequences if you are wrong.
Big boy rules here.
On pistols with no buffer tubes put what ever you want on them relative to sights. Without a brace/stock or buffer tube, there is no way that they can be considered an SBR. For this we are talking about rifled barrels here and shotguns are more complicated.
As of now any brace pistol unless it and everything on the gun passes ATF approval may be an SBR. One might still have a chance in court to challenge the ATF assigned SBR status. When I say everything on it, that means the sights and optical sights also. They want to see the entire package and any change could make the gun an SBR in their opinion.
I have no intention in possibly getting caught up in something like that. I have my retirement set and do not want it to take a change of venue like a federal court room and that will take every penny that I have and could end up in a federal prison.
Likely next year the whole brace ruling gets thrown out anyway.

[TD1886]

You know Larry Gibson asked me to take this 22LR conversion unit thread and start a new thread when I took the thread we both were in off topic. If you two fellows want to talk about the SBR's, ATF, etc, would you please start a new thread? Please?

[M-Tecs]

If you don't want thread drift don't post garage and expect pushing garage to go unnoted. At one time the conversation units were the only game in town. We have more options today. Pointing out the real limitations of the conversion units is helpful for all. Making claims like The ATF forbids iron sights or fixed focus scopes on AR pistols. and then you are stating that's it's a good post not so much particularly when it's factually wrong.

It's good that you are pointing out that to get even mediocre accuracy you need to swage the bullets. Same for me pointing out that if you are going to purchase new better options are available for not much more money. I've had to qualify too many times with them and used them too much to not know there are better options. After I moved to dedicated uppers my three M261's have been fired very little. My dedicated uppers get used a lot. If you don't want other people's comments you can always PM or email.


my reason for the conversion is the trigger and sighting arrangement are identical since an AR pistol more of closer range combat weapon. 100 ft is my max .22 training range for now. If I want shoot further I will have to use 5.56.
Since it being used with rimfire full strength springs are required for the trigger - hammer group. Buy a dedicated upper and you need a new optic. The ATF forbids iron sights or fixed focus scopes on AR pistols.


Good post

[TD1886]

If you don't want thread drift don't post garage and expect pushing garage to go unnoted. At one time the conversation units were the only game in town. We have more options today. Pointing out the real limitations of the conversion units is helpful for all. Making claims like The ATF forbids iron sights or fixed focus scopes on AR pistols. and then you are stating that's it's a good post not so much particularly when it's factually wrong.

It's good that you are pointing out that to get even mediocre accuracy you need to swage the bullets. Same for me pointing out that if you are going to purchase new better options are available for not much more money. I've had to qualify too many times with them and used them too much to not know there are better options. After I moved to dedicated uppers my three M261's have been fired very little. My dedicated uppers get used a lot. If you don't want other people's comments you can always PM or email.

The thread was to determine why there is inaccuracy when the unit is used in the 7 twist rifle, not that there are better options, which most of us are all aware of. Apparently you missed that and that's why Larry Gibson wanted this thread. I particularly asked Larry what where reasons for this inaccuracy and pointed out the three main question of what it indeed the twist, or was it the 22LR bullet being undersized, was it the unit is a separate part inserted into the barrel.

My comment to barnetmill was he had a good reason for the conversion unit.

Again the thread isn't about a better option.

[barnetmill]

If you don't want thread drift don't post garage and expect pushing garage to go unnoted. At one time the conversation units were the only game in town. We have more options today. Pointing out the real limitations of the conversion units is helpful for all. Making claims like The ATF forbids iron sights or fixed focus scopes on AR pistols. and then you are stating that's it's a good post not so much particularly when it's factually wrong.

It's good that you are pointing out that to get even mediocre accuracy you need to swage the bullets. Same for me pointing out that if you are going to purchase new better options are available for not much more money. I've had to qualify too many times with them and used them too much to not know there are better options. After I moved to dedicated uppers my three M261's have been fired very little. My dedicated uppers get used a lot. If you don't want other people's comments you can always PM or email.

Well my last post was correct and I am not getting into a whizzing contest here, we should be better than that here. I have learned a lot here from the thread.

[TD1886]

It's good that you are pointing out that to get even mediocre accuracy you need to swage the bullets.

If my post was read correctly it wasn't only swaging the bullets that increased accuracy it was the mechanical alteration that was the thing that greatly enhanced it.

[M-Tecs]

Okay Mr Larry Gibson, this is kind of the test you and I have been waiting for. I got the Colt unit today, was suppose to be here yesterday, but we had some really horrible thunderstorms that resulted in trees down and a power outage of 10 hours for me. So here is what I did. I tested at 25 yards just to see what I'm going to be working with. I won't lie the results at that distance weren't very gratifying. So then I started swaging the 22's. I had the unit out and it's has a generous chamber and accepted my swaged ammo A Okay. Let me remark at this point the Colt unit appears to be very much a copy of the military M261 except for one thing, the magazine. Colt supplied a decaded magazine. Back to the test. The swaged bullets reduced the groups by 50% or so. Still not what I was looking at. I checked out some things on the unit and saw what I thought all along might be the accuracy problem. I'm not going to mention here (sorry guys) because it is a permanent modification to the unit and requires tools that most people won't have. So I done that and went out again at 25 yards with the swaged bullet. VIOLA!! The group improved by almost a 100%. It shot a raggy butt hole at 25 yards, say in the order of smaller then 1/2 inch easy. Very very encouraging so now to test at a further distance and not with one brand of ammo, but various 22 ammo I have. BTW that initial test ammo was PMC. I hope the old 7 twist HBAR holds up to some useable accaracy at further distance.


If my post was read correctly it wasn't only swaging the bullets that increased accuracy it was the mechanical alteration that was the thing that greatly enhanced it.

Some of us do have the capability to modify the units. Probably more than you think. Sharing would be helpful and appreciated for all even for those that don't have the capability to do the mods.

As I stated I have three of the AF 261's. I also have one USGI 601 14 twist upper and two USGI 604 uppers with 12 twists. Getting them to shoot well with the conversion units would be nice. I would also be interested in knowing how the modified unit shoots without swaging the bullets.

[barnetmill]

If my post was read correctly it wasn't only swaging the bullets that increased accuracy it was the mechanical alteration that was the thing that greatly enhanced it.

I plan to buy that unit that was mentioned. I just got back into town and am a little behind.


https://borebuddy.com/product/borebuddy-chamber-adapter/
$52.50 – $61.50
Swap the collar on your bolt for this chamber adapter to shoot 22lr through any standard 223/556 AR. The chamber adapter is compatible with BoreBuddy/CMMG/RTB/Palmetto 22lr bolt groups.
Even if my task does not demand it, I want the most accuracy that I can get. Says will work with CMMG that I have. Better alignment might make the gun run better and reduce leading also.

[TD1886]

I plan to buy that unit that was mentioned. I just got back into town and am a little behind.

Even if my task does not demand it, I want the most accuracy that I can get. Says will work with CMMG that I have. Better alignment might make the gun run better and reduce leading also.

barnetmill there are many things wrong with that CMMG unit. I can give you a link to where an original M261 conversion unit is for sale, a bid site, but he has buy it now too which I believe that price may be cheaper then the CMMG unit. As you noticed on that site that sells that buffer tube adaptor that they sell other things like the gas blow back block you put in the charging handle. What I'm getting at if you have to do all that to the CMMG unit to make it work better, it's better to start out with a device that is better from the start. On the Colt and military M261 they have a flat spring sticking up on the read of the device at 12 o'clock and that presses against the buffer to keep the device forward. It doesn't need that bore buddy. Also the Colt and M261 doesn't blow gas back at you. If you wish to have the link I'll pm it to you, just let me know.

[TD1886]

Some of us do have the capability to modify the units. Probably more than you think. Sharing would be helpful and appreciated for all even for those that don't have the capability to do the mods.

As I stated I have three of the AF 261's. I also have one USGI 601 14 twist upper and two USGI 604 uppers with 12 twists. Getting them to shoot well with the conversion units would be nice. I would also be interested in knowing how the modified unit shoots without swaging the bullets.

As I said I just initially started testing my Colt unit. It was preliminary to see what I was dealing with. You brought a good question as to how it shoots with regular non swaged 22LR's with the modification. I will find out, but suspect it won't be as good and that's an assumption.

When Larry chimes in I'll ask him if he thinks it's a good idea to post the permanent modification.

[barnetmill]

barnetmill there are many things wrong with that CMMG unit. I can give you a link to where an original M261 conversion unit is for sale, a bid site, but he has buy it now too which I believe that price may be cheaper then the CMMG unit. As you noticed on that site that sells that buffer tube adaptor that they sell other things like the gas blow back block you put in the charging handle. What I'm getting at if you have to do all that to the CMMG unit to make it work better, it's better to start out with a device that is better from the start. On the Colt and military M261 they have a flat spring sticking up on the read of the device at 12 o'clock and that presses against the buffer to keep the device forward. It doesn't need that bore buddy. Also the Colt and M261 doesn't blow gas back at you. If you wish to have the link I'll pm it to you, just let me know.

Thanks for the detailed advice. The gas blow back is not a big deal for me since i have set the gun up for cheek shooting that entails a very high mounted sight and my eyes are well above it. I have not had any real complaints yet with system other than certain brands of remington ammo for example bend while the cmmg unit is trying to them into the gun. Their brass case is weak and bends for their cheaper plinking ammo and unfortunately i have a lot of it. I have three mags and unit and it all works reasonable well. For another $60 or so, if the collar will work, that is about as far I would want to go. Thanks for the offer of the link, but for now I will pass on it.
But I will do some reading on the cmmg and see what it failings are. What I see so far is that it is a one size fits all and so is loose. I typically fire about 200-350 rounds in a session. Lately it has been too hot here in florida and I may wait till September.

[M-Tecs]

As I said I just initially started testing my Colt unit. It was preliminary to see what I was dealing with. You brought a good question as to how it shoots with regular non swaged 22LR's with the modification. I will find out, but suspect it won't be as good and that's an assumption.

When Larry chimes in I'll ask him if he thinks it's a good idea to post the permanent modification.

If you don't want to publicly post them you can PM or email me if you want. It would be appreciated. Here's a free download for the TM 9-6920-363-12&P. Operator's & Organizational Maintenance Manual Including Repair Parts & Special Tools List. Conversion Kit (Caliber .22 Rim fire Adapter) M 261 for Rifle M16 & 16A1.

https://www.liberatedmanuals.com/TM-9-6920-363-12-and-P.pdf

[TD1886]

Thanks for the detailed advice. The gas blow back is not a big deal for me since i have set the gun up for cheek shooting that entails a very high mounted sight and my eyes are well above it. I have not had any real complaints yet with system other than certain brands of remington ammo for example bend while the cmmg unit is trying to them into the gun. Their brass case is weak and bends for their cheaper plinking ammo and unfortunately i have a lot of it. I have three mags and unit and it all works reasonable well. For another $60 or so, if the collar will work, that is about as far I would want to go. Thanks for the offer of the link, but for now I will pass on it.
But I will do some reading on the cmmg and see what it failings are. What I see so far is that it is a one size fits all and so is loose. I typically fire about 200-350 rounds in a session. Lately it has been too hot here in florida and I may wait till September.

As you mentioned the CMMG fits loose, it sends gas down the charging handle groove, and it's the only one out of the two being the Colt and M261 that has the full 5.56/223 piece that inserts inside the chamber and by full I mean it even has the case neck. Whether that is good or bad I don't know. I do know that it's mighty thin for the 22 bullet having to pass throught it. CMMG at one time had some sort of failure around that part that is shaped like the cartridge. Usually CMMG makes quality parts and firearms in my opinion. Their radial delayed blow back system is genius they have on their pistol caliber rifles and carbines.

[M-Tecs]

I've never inspected the standard M261. Is the chamber insert rifled same as the AF version?

[TD1886]

I've never inspected the standard M261. Is the chamber insert rifled same as the AF version?

I've never examined the M261, but the Colt, which is almost identical, is not. Wouldn't that be kind of odd? The chamber insert would give the bullet some speed as the 22LR is pretty efficient in a short barrel, so what twist would it be if it was rifled? Wouldn't that make matters worse if it was and then the bullet hits the rifling of the AR's barrel? Larry mentioned one of the things that might hurt accuracy with the 7 twist is the bullet hitting that steep angle of the rifling and damaging the bullet.

Not that anyone is doubting you, but are you positive the AF one is rifled? Can you take a picture of that and post it? This is most interesting.

[TD1886]

I've never examined the M261, but the Colt, which is almost identical, is not. Wouldn't that be kind of odd? The chamber insert would give the bullet some speed as the 22LR is pretty efficient in a short barrel, so what twist would it be if it was rifled? Wouldn't that make matters worse if it was and then the bullet hits the rifling of the AR's barrel? Larry mentioned one of the things that might hurt accuracy with the 7 twist is the bullet hitting that steep angle of the rifling and damaging the bullet.

Not that anyone is doubting you, but are you positive the AF one is rifled? Can you take a picture of that and post it? This is most interesting.

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?

[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.

316780 316781

[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.

316780 316781

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:

316792

316793

316794

[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:

316792

316793

316794

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.

316814

[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.

316814

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 316819

Federal Valuepak 36 gr HV HP OOB; 316820

Winchester SuperX HV HP OOB; 316822

Winchester SuperX HV HP Waltz; 316823

[Larry Gibson]

Continued;

CCI Standard Velocity Target Waltz; 316824

CCI Standard Velocity Target OOB; 316825

Remington Golden Value Pak Waltz; 316826

Remington Golden Value Pak OOB; 316827

[Larry Gibson]

Continued;

CCI Velocitor OOB; 316828

CCI Stinger OOB; 316829

Remington Yellow Jacket OOB; 316830

Winchester 525 Bulk Pak Waltz; 316831

[Larry Gibson]

Continued;

Loads tested with Colt HBar with 9" twist;

CCI Velocitor OOB; 316832

Remington Golden value Pak Waltz; 316833

CCI Standard Velocity Target OOB; 316834

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]

316836
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]

316836
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.

316838

[barnetmill]

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

Out of curiosity, In rifle barrels was the CCI SV target 'subsonic'. As you stated for high volume use the lead outside wax lubricated bullets will require cleaning at a lower round count in a blow back rifle.
Some of the 50 yard .22 bench rest rifle people say they never clean their rifles. They ammo that they shoot from what I have seen often has either wax or a grease on the bullets. The guns are bolt actions and so a tight chamber is more readily fed a round.

[TD1886]

Larry let's address the Browing rounds not firing. I rechambered them so the firing pin would impact another spot on the rim and still no bang. Also I fired more Browining after that inaddition to other waxed bullets and they all went bang. I shoot a lot of 22LR and as lately quality control has gone downhill. It was the three Browning rounds that weren't good. Maybe I'll pull the bullets and see what I find inside.

I didn't miss the obvious. If you read what I mentioned previously if that conversion unit misaligns even the slightess amount it can start the bullet crooked into the bore. So if you have a crooked bore in the bore which twist is going to amplify that the most, the 12 twist, the 9, the 8, or the 7? BINGO! Yup you got it right the 7 twist.

I'm not finished yet and I still have more tricks up my sleeve to get these conversion units shooting better in all twists.

[TD1886]

Okay Larry let's get a little more serious. First off I removed my unit from the gun and I was shocked at how clean it was. No wax, no nothing on the breech face the cartridge rim is up against.

Okay I measure the unit's cartridge (by that I mean the part that goes into the chamber of the rifle) and a fired cartridge. Here are the figures

Fired cartridge Device Cartridge Difference

Ahead of ext. groove .375 .373 .002
At the shoulder .3563 .3535 .0028

I couldn't measure the length to the datum line on the shoulder so I assume it has tolerance in it too.

Now do you expect something fitting like that is going to give you target bolt rifle accuracy? I don't. Who's to know between each shot if flip flops around and maybe not being in the same position all the time is were the fliers come from amplified by the 7 twist?

Only one way to do this and I'm not going to put the money out for, but that is have a 7 twist barrel made for a 22LR with a match chamber on a bolt action. Now if I could come by a 20 inch 5.56 barrel I would be willing to fit it to a junker 22LR bolt gun I have, even though the bore would be larger. Guess I would have to swage up the ammo in that case.

Your default is the 7 twist, it's not mine.

[Larry Gibson]

Out of curiosity, In rifle barrels was the CCI SV target 'subsonic'. As you stated for high volume use the lead outside wax lubricated bullets will require cleaning at a lower round count in a blow back rifle.
Some of the 50 yard .22 bench rest rifle people say they never clean their rifles. They ammo that they shoot from what I have seen often has either wax or a grease on the bullets. The guns are bolt actions and so a tight chamber is more readily fed a round.

Yes, the CCI SV Target was indeed subsonic. I chronographed it out of both the AR/M261 and my Ruger 10/22, both suppressed. With the suppressor there was no muzzle blast to trigger a close start screen so the start screen of the Oehler M35P was just a couple inches in front of the suppressor. That effectively measures the muzzle velocity within a couple fps. The average velocity out of the 18" 10/22 barrel ran right at 1050 fps and out of the 20" AR barrel right at 1055 fps. There is no "snap" of sonic crack in front of the suppressor so, as I mentioned, all one hears is the action functioning and the whop of the bullet striking the target. The use of outside lubed lead bullets in blowback actions does indeed require cleaning as buildup of the powder/lube residue can lead to misfires from the bolt not fully closing. This also applies to my Browning Challenger pistol. In My Colt Ace M1911 conversion the floating chamber will lead/powder foul up within 50 - 100 rounds of lead lubed 22LR ammunition and cease to function. With copper plated 22LR ammunition if will not lead/powder foul up and will continue functioning. However, I do clean it after every use.

As for my bolt action rifles, I shoot 100 yard 22LR BR matches with my Remington M37 Target rifle. I clean it once a year maybe. Maybe, but only if the groups open [my score falls off not due to me or the wind]. I only shoot the higher end target ammunition in it, usually Lapua Midas+. I shoot a mix of different kinds of ammunition in my Remington M504 w/o any problems. I usually will run a dry patch through the bore when switching ammo is all. Same goes for my Norinco M98 trainer. With my old single shot 22LR rifle I shoot shorts, longs and long rifle 22 ammo through it and don't remember the last time it was cleaned.

Note; "cleaning" to me refers to the inter of the action and the bore. I keep the exterior of all my firearms clean and lightly oiled.

[Larry Gibson]

TD1886

Not having any Browning 22LR ammunition or having ever fired any I cannot speak to the quality or lack thereof.

As to the lack of any residue/fouling in the action of your device, apparently your experience varies greatly from mine.

In an earlier post of mine in this thread or perhaps the other thread I stated the possibility of the long throat of the devices and the possibility of damage to the bullet was likely. That, of course, was just an opining based on the probability of some misalignment. However, the continuously demonstrated decrease in accuracy as the twist gets faster is ample proof the increased centrifugal force is acting more on whatever those damages (imbalances) are. It is not a "default", it is proven fact.

As I said, doing what you are doing you may very well find a combination of modifications and ammunition selection that may give adequate accuracy out of your 7" twist AR for your needs. Keep at it, who knows. If you have the money and the desire to build a 7" twist 5.56 barreled bolt action 22LR then be my guest. It will be interesting to the results. I'd venture the accuracy may improve because the bullets probably wouldn't get damaged as much because of the standard chamber, ergo the centrifugal force of the increased RPM (over that of a 12" twist barrel) won't have as much imbalance to act on.

However, I've no intention on trying to turn any of my ARs into target/match rifles using 22LR in 5.56 barrels. The M261 device in my 12" twist AR with several different brand/types of 22LR ammunition suits my needs for it very nicely. Thus, I'm a happy camper with it and, like they say.....if it ain't broke, don't fix it.

[TD1886]

As I said, doing what you are doing you may very well find a combination of modifications and ammunition selection that may give adequate accuracy out of your 7" twist AR for your needs.

Larry I've already demostrated that. I said my 7 twist HBAR is minute of squirrel at 50 yards. I'm just having fun with it. I have a bolt 22LR that can out shoot most the high dollar target 22LR's. Off topic a wee bit, but still on rimfires, I've said for years that the 22 Magnum could be made extremely accurate and I've proven that, to myself, with a target AR15 in that caliber. I got a special chamber reamer, bought a Green Mountain 22 Magnum barrel, (what's thats? That's a barrel dedicated to the 22 Magnum, has the correct bore and groove, but 14 twist) put it on an AR15 as a bull barrel and indeed it does shoot very well. It's past time the manufacturers start building more accurate 22 Magnums.

Now back to the AR15 using 22 conversion kits. I'm out to prove that the 7 twist can be just about as accurate as the 12 twist when all the conditions that cause it to be less accurate in a 7 twist are recognized and fixed. So far I think I'm heading in the right direction. This is not to turn the AR15 with the 22 convesion kit into a match rifle as I already have that in other 22 firearms. One more thing on my HBAR I don't have a free floating barrel and forearm tube like yours does. Mine is a stock pre ban HBAR so the resting the forearm/barrel on the front rest can and does influence how it shoots. So we shall see what I get in the end. I have many irons in the fire and this may take a while.

This week I will see how I can get the conversion device to fit the chamber better. I'm going to check to see if the datum line on the device chamber does indeed butt up against the datum of the rifle's chamber. I realize the military wasn't out to turn a M16 into a match target rifle and was only a cheaper means to train soldiers. Maybe we shall find out what it is really capable of.

I appreciate your help on this so far and hope it continues.

TD

[Larry Gibson]

TD1886

"I'm out to prove that the 7 twist can be just about as accurate as the 12 twist when all the conditions that cause it to be less accurate in a 7 twist are recognized and fixed."

Good luck with that.

"One more thing on my HBAR I don't have a free floating barrel and forearm tube like yours does."

No, my 12" twist milspec barreled AR does not have a free floating barrel, it is milspec with M16A2 handguards. My Colt HBar with a 9" twist heavy barrel is free floated with a tube fore end.

[TD1886]

TD1886

"I'm out to prove that the 7 twist can be just about as accurate as the 12 twist when all the conditions that cause it to be less accurate in a 7 twist are recognized and fixed."

Good luck with that.

"One more thing on my HBAR I don't have a free floating barrel and forearm tube like yours does."

No, my 12" twist milspec barreled AR does not have a free floating barrel, it is milspec with M16A2 handguards. My Colt HBar with a 9" twist heavy barrel is free floated with a tube fore end.

That clears up the rifles you have, thanks.

Okay today I took the unit out of the rifle and cleaned it. Then I marker pen the entire cartridge chamber on the end of it in addition to the round base of it that fits into the barrel extension at the lugs area. It confirmed my fears. There was one part of it that contacted the chamber. I was especially interested in the datum line on the unit cartridge and there were zero marks on it. I'm right, at least with the Colt unit, that it's basically loose in the chamber of the rifle. No wobbly loose, but loose in the sense not touching. I have the diameter of the unit cartridge portion in comparison with a fired 5.56 and the two area's I measure the unit cartridge was .002 and .0028 difference. That's a lot of slop so that bullet has a huge chance of entering the bore crooked and the 7 twist has a huge chance of killing it's accuracy with the high rpm.

I think the accuracy with my unit and rifle will suprise you. So far it's very usuable at 50 yards.