AR in .22 TCM?

[kBob]

Just playing around in my head again.

Got to wondering if it might be possible to do a conversion to .22 TCM in a AR.

I wondered if it might be possible to do something like a US NAVY chamber plug such as was used to convert .30-06 M1 Garands to .308, come up with a mag adapter to fit the long front to rear .22 TCM magazines (mayhaps mod an existing adapter to use TCM pistol mags) and use the ARs existing gas system and locking. Might not get the right port pressure to work the action reliably though, but who knows without trying or having the numbers in front of you?

Just an idea. One might have a rifle one could drop a dedicated .22LR upper on, or the Hornet powered .22 TCM upper or a normal .223/5.56 with a single lower.

Just playing bur woundered what folks thought. Kind of surprised the Philipinos don't already offer a dedicated .22 TCM upper (DI, Piston, or blowback) and mag adapter actually.

On a related note..... how about a chamber adaptor for a .223 bolt gun? I figure some folks with the pistols might spring for a low dollar chamber adapter before dashing out to buy a new .22 TCM rifle even if it ends up being a single shot. Got to be away to remove an existing magazine to replace the inards ( follower and spring) with a shortened magazine with its own spring to allow .22TCM to function as a repeater in say and Axis or some such.

All might be of interest to folks that have one of the high cap pistols.

-kBob

 

[Riomouse911]

TCM is a 9mm sized case, may require 9mm AR blowback lockwork and mags, and a.22 TCM-chambered barrel. I doubt you could get a barrel plug ala the .22 Jet/.22lr to work very well at all in a 5.56 AR.

 

[someguy2800]

A 9mm case is bigger than a 223 case. I agree that a 9mm upper and lower is the correct platform to start with.

 

[drband]

The 22TCM case is based on a cut down .223 case. The neck of the 22TCM makes the case slightly longer than a 9mm case, however, the case head diameter is smaller than 9mm.
See the pdf.
It seems that a .223 upper would work to adapt for this fun cartridge.
(I apologize for the weird graphic, but it’s all I could post from my phone)

 

[kozak6]

Chamber plugs are usually a bad idea.

thearguy.com has barrels. Apparently, he uses a pistol length gas system on a 16" barrel. There's been some success using them over on arfcom.

 

[tallpaul]

http://thearguy.com/news a lil bit down the page they say they have a working 22tcm

 

[boom boom]

http://thearguy.com/news a lil bit down the page they say they have a working 22tcm

Checked them out--they sure enough have some odd chamberings.

 

[hdwhit]

kBob wrote:
Got to wondering if it might be possible to do a conversion to .22 TCM in a AR.

Since the 22 TCM cartridge is based on the 223 Remington case and has the same shoulder angle and neck configuration (essentially, half a inch has been taken from the middle of the case), it should be fairly straight-forward matter of obtaining a new barrel, figuring out how far out on the barrel to tap the gas (and how big the gas port should be) and then modifying the magazines to properly feed the cartridges.

As far as a bolt gun, Rock Island already makes one chambered for 22 TCM from the factory.

The Wikipedia page for the 22 TCM reports it launching a 40 grain bullet at 2,800 fps out of a 22.75 inch barrel. This is comparable to the 2,750 fps I get out of an 18 inch barrel with my Iver Johnson carbine chambered in 22 Spitfire (which uses 30 Carbine as the parent case). If the conversion is done well, I suspect you would find it a joy to shoot.

 

[Sunray]

"...US NAVY chamber plug..." Didn't work. They tended to come out upon extraction without any warning or indication until your empty looked funny. Even the Boat People found it was best to buy a barrel.
"...A 9mm case is bigger than a 223 case..." Yep. 16 thou bigger. It'd need a bit of extractor work.