I don't have any full auto stuff so using the Ciener mag with the M261 unit seemed more productive since I use slide-in barrels in both 22lr and .17 Mach2 and the M261 unit will do both rounds without any modification.

This is the top of the mag -- notice how far forward the magazine is in the magwell adapter. Also notice the short ramp that is in front of the magazine.

This is the modified mag showing the profile.

this is the modified Ciener mag in my carbine ready to load a round. The bolt on the M261 can be locked back manually.

I ran a couple of full mags through the carbine to see how the mag works and it is flawless.

Nice job.  Looks good.

Dan

Please tell, what is the M261?

Quoted: Please tell, what is the M261?

The M261 GI 22lr conversion unit was designed to be used in M16's for markmanship training purposes. It cost less to shoot 22lr than 5.56mm. The M261 conversion unit is no longer made but there are enough of them floating around to get at a fair price. The only drawback was the 10 round insert mags -- these insert mags had to be slipped into a standard GI M16/AR-15 magazine so they could function in the M16/AR-15 and look and feel like a standard GI mag. A lot of people really like the M261 but wish there were higher capacity mags available -- like the Ciener 30 round mags.

I kinda robbed this picture of the M261 with the magazine inserts from a person that has them for sale over in the "equipment exchange".


The conversion unit is pictured above the 4 magazine inserts. By the way, if you've never seen the M261 before, the unit in the picture is up-side-down -- the spring is mounted of the top of the unit.
I did the Ciener magazine modification for two reasons -- I wanted a high-cap mag for my M261 that I can shoot the .17 Mach2 round in and since my upper is a convertable I can change out the barrel liner and also shoot a tone of 22lr's. the Ciener 30 round mag runs around $60 so I'm now in the process of hunting down some less expensive mags -- I've found some good 20 rounders and I have done one of them already but I need to find a better supply of them.