Magazines for Compass Lake Upper

[acourvil]

Anyone have a Compass Lake Upper? What are you using for magazines?

The Compass Lake upper is based on the M261 army conversion. They do a dedicated 22LR match barrel with the proper twist, and they have a reputation for being very accurate. But they use the M261 magazine inserts, originally intended to load into 30 round 223/556 magazines. They do not fit in 10 round magazines. The standalonne magazines (Black Dog) available for other 22LR uppers do not work in the Compass Lake upper.

So if you have one, what are you using for a magazine?

[SilentPea]

These guys at ARFcom seem to have found a way to do it in short body 10 rounders. (last post or two) Might be worth grabbing a few of the cheap ASC aluminum 10 rounders to dedicate to rimfire hosts.

[acourvil]

yeah, saw that. My first attempt to modify a regular 10-rounder didn't work well enough to use. I need to get a couple 10/20 mags and try those, I guess.

[brassburnz]

I've used the M261 mag inserts in 20 round, straight body mags. I just ordered some BDM mags from Midway that say Olympic .22 conversion. The Olympic Arms conversion is based on the M261. BDM does have mags for the M261/Olympic Arms conversion.

https://www.midwayusa.com/product/498204/black-dog-machine-conversion-magazine-ar-15-olympic-rimfire-conversion-22-long-rifle-10-round-polymer-smoke?cm_vc=S014

http://blackdogmachinellc.net/M261MAGAZINES.aspx

[acourvil]

Yes, I tried those. Even the "M261" BDM mags do not work with the Compass Lake Upper. Want a couple more?

[brassburnz]

Yes, I tried those. Even the "M261" BDM mags do not work with the Compass Lake Upper. Want a couple more?

The BDM M261 mags should arrive in a day or two. If they work with my conversion, I'll send you a PM

[acourvil]

Just a quick update in case anyone else runs into this problem. The M261 magazine can be used with either a AR Stoner 10 round magazine, or a straight body 20 round magazine repair kit. In either case, throw away the follower, flip the spring over and put it around the M261 magazine, and re-assemble the magazine. It requires dedicating the magazine bodies to the M261, but both work reliably. And it is a California legal magazine.

As a side note, the Compass Lake upper apparently has different spacing that other M261 based uppers; the Black Dog magazines do not work because the feeder is too far back and hits the bolt.

I'm still working out some other issues with the CL upper, but based on initial testing, it is very accurate.