This is a picture of the modified M261 bolt. There is no spring because I use an Op-Rod that makes contact with the standard carbine buffer. The bolt unit slides into the upper receiver like the Kuehl or Accuracy Speaks type systems since the chamber unit is perminent in the 1/12 twist GI barrel.

This is a picture of the Marlin 22 magnum magazine, the adapter block that slides into a 20 round AR mag and the whole thing put together.

Finally, the magazine in the rifle with a round aimed at the chamber and below it the rifle this setup works in. The only bad side right now is the mags are good for only 7 rounds.

By the way, this was just a "I wonder if it can be done" type project. I imagine it can be done with some mods to any type 22 conversion unit.

Pretty cool.  What type of $$$ do you have in it and How long did it take you to make it?

Dan

Cool!  If it can work for the .22mag it can work for the .17HMR!  Are those rem. mags?  I know you can get higher cap H&K magazines for that cal.

I can't really say what the cost was because I don't know. A friend was nice enough to give me an ASA 9mm upper receiver, I bought the M261 conversion a long time ago for $150 new. The Mags are Marlin and run From $8 to $12. I got the 1/12 twist shot-out barrel from SARCO for about $40. I had tried other twist barrels and the bullet jackets are to fragile for the faster twists. I did spend a lot of money on dead ends -- I tried to bore out a chromed barrel and when I got to the gas port hole area the piloted drill took a bite and broke. The bit was jammed solid in the bore and that was the end of that.
I was going to make a carbine next in the .17 HMR but I discovered that Brownells doesn't have a muzzle crowning cutter that will work with the small .17 caliber bore and I don't have a lathe. I decided I would stay with the 22 magnum because I have all the chamber reamers, throating reamers and the crown cutter for the 22 magnum. I guess if you added up the cost of all the things I went through to get to this point it would equal the cost of having a gunsmith make it. I had a lot of fun doing it myself although the SARCO barrel gives just so-so accuracy -- that's the reason I'd like to build a carbine but use a barrel liner. I've ordered a carbine barrel from American Manufacturing that is already bored out for a liner.
By the way, I had to do a lot of testing to get the buffer setup to work. The rifle pictured has a full length buffer tube, a carbine buffer spring, the plastic spacer and carbine buffer. the final setup required all the weights to be removed from the carbine buffer so it is just a shell with the plastic tip on the end.

Dude! That's a kick ass project! Good job!

Excellent Project....