After 5 months of patiently waiting I finally received my "semi-space gun" upper from Compass Lake Engineering.  I have posted my official picture to the forum. The rifle uses the 10 round magazine adapter assembly which fit into a standard .223 magazine.  My question regards the fit of the adapters in the .223 magazine.  I installed an adapter in an old Colt 20 round mag.  The adapter is free to wobble about a considerable amount fore and aft. Is this a concern?  

In my initial tryout of the rifle I had the adapter installed in a 20 round mag with a no-tilt follower.  I found that the bolt would drag on the magazine adapter and would not fully chamber the first round. It cycled fine when fired.  Also the dust cover would not stay latched when the empty magazine was inserted(?)  Those problems do not seem to an issue with the Colt mag although the weather is a little foul and I will not shoot it again until tomorrow to verify.

TIA,

Ken

M261?  Run them wet


Additionally, they don't hold the bolt back on last round.

Moreover, they won't work with a auto sear.

Lastly, go buy some BlackDog mags

Definitely go with some BDM mags.  I got 5 M261 magazine inserts with my adapter, but they are a royal pain to get in and out of the standard magazine (but they are a good use for goofy AR mags...).  My BDM mags, on the other hand, are easier to load, easier to insert, and run great,

Run the adapter wet, and keep it clean, and it'll be more fun than puppies.

I put mine in old, bone stock 20 round mags and they are 100% reliable - better than my BDM's.

Here's a dumb question - did you gut the mag before putting in the insert? That's the only way I can imagine it would be loose. Mine are tight.

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If the 20 in question is one of the curved mags, you're on uncharted territory.  They were intended for use with the bazillions of old straight 20s the army had i stock.

On he contrary.  The standard M261 magazine inserts work fine in 30 round mags.  They are just more of a pain to insert than in 20s.  Further, a 30 round mag with somewhat sketchy feed lips will hold the insert very well, thus my statement that the inserts give you a good use for flakey mags.

Thanks for all the advice.  Please allow me to add...

- The first mag I tried was in fact a curved 20 round from C-Products. It has been relegated to "don't use with adapter" status.
- I tried another Colt 20 round mag. The adapter still moves a little fore and aft. I have not had a chance to fire it yet.
- How do I tell if the hook is under the follower? I pulled the base plate from the first Colt mag and fiddled with the adapter and follower. Darned if I can get the hook under the follower. It appears that the bottom of the adapter rides on the false cartridge molded into the right side of the follower. The hook does not even touch the follower. I need some more info on this.
- I guess something light such as Rem Oil would be the thing to "keep it wet"?
- Finally, BlackDog mags are not currently available on this planet. I will stick with the original adapters for now.

Thanks again,

Ken

Hello Forest,

Perhaps the adapters you have are a little different than mine.  The hooks on the 3 I have only extend about 5/32" below the base of the adapter. If I hook one on a follower, not installed in a mag, the base of the adapter on the opposite side from the hook hits the false cartridge.  The adapter projects at an angle of about 30 degrees towards the hook side. I do not see how that would be possible within the magazine.

That said, I have come across another possible configuration.  I really wanted to install the adapters in 10 round mags.  Of course they will not fit. Unless...

Disassemble the mag
Remove the follower from the spring
Wrap the spring around the adapter (upside down - with the loop which holds the follower at the bottom)
Insert the adapter from the bottom of the mag shell
Compress the spring and reinstall the base plate

I just installed an adapter in an "AR-Stoner" 10 round mag from midwayusa.com.  I seems to fit like a glove. I will give it a try and post the results. THIS MIGHT BE AN OPTION FOR FOLKS FACING POLITICAL CONSTRAINTS.

Ken

I just ordered some 10 rounders last night from 44Mag. I just checked and they show 10's.15's and 26's in stock.

http://www.44mag.com/category/black_dog_machine/a

Just a quick update...

I spoke with Frank at Compass Lake Engineering.  He advised me that with a little practice one get used to squaring up the insert in the magazine after loading it and that the first round will feed reliably.  I took this good advice and combined it with my own experience that after the first shot the insert was very reliable. Here is my current SOP:

1 - load the insert with as many cartridges as desired
2 - tilt the front of the insert up as high as it will go
3 - make sure the M261 bolt is forward
4 - insert the magazine fully into the mag well
5 - pull and release the charging handle

This has proven to work very well.  My theory is that the M261 bolt will push down the front of the insert to the desired position to facilitate loading the first cartridge.

As to my experiment with installing an insert in a 10 round magazine using just the mag spring, no follower... Nothing to report on that so far. Sorry.  I have a couple of other work items ahead of that.  I will do some testing and report back. I promise.

Ken

Big CLE fan.

#2 is the most important bit from my experience.  The insert really needs to "float" easily.  If it's binding it's likely to cause problems.  

The CLE chamber adapter takes out most of the bolt wobble, improving accuracy but does make it less mag forgiving than a stock m261 with the chamber insert.

The old straight 20 mags work best, but I've had decent reliability with most standard mags following essentially the steps you outlined.

I also tend to tip up the first round... sometimes I've found it's nosed down a bit.

BDMs are a bit harder to tweak in the CLE/261 setups because they don't float/adjust like the inserts.

where are there mags in stock? at least >10rounders

nevermind. just found some 25 rounders at blackdog machine website.

http://blackdogmachinellc.net/olympic-m261.aspx

Those are the mags I use to put my 261 adapters in.  Only problem - I'm not sure I can get the adapter out once it's in.  The AR Stoner/Armalilte 10 round mags are steel and the same size as the standard straight 20 rdrs.  The follower can actually bottom out in the mag but only 10 rounds can be loaded because there are indentations on sides of the mag body that prevent more than 10 rounds in the mag.  The follower has cutouts/grooves that allow it to go down past the indentations/cartridge stops.  In other words - most short 10 round mags cannot take the 261 adapters and neither can mags that stop the follower to limit the mag to 10 or less rounds - Colt 20/5s and the old C-Products 20/10s.  Years ago I also used some beat-up 30 rounders - both aluminum and the Israeli Orlites - worked okay for me.  

"THIS MIGHT BE AN OPTION FOR FOLKS FACING POLITICAL CONSTRAINTS."
Sadly I can't have the 20 or 30 rounders anymore. We got a law banning mags over 10 rounds that "fit in a pistol". AR pistol means all AR mags come under the law.  Mini-14s, M1As and AR-180s(the originals with original mags) are not covered.  ARs, M1 carbines, AKs and, IIRC, HKs are limited to 10 rounds. Some ignore the law cause they say they are rifle mags - some of our shooters who are lawyers and judges have looked at the law and told us any mag that can fit a pistol - rifle mag or not - must not be over 10 rounds. YMMV

Mine is somewhat picky about host mags too.  I have a bunch of ban-era steel SA80 mags that work well, leave the adapters in them, and use them as dedicated M261 mags.

Just took apart 20 retro 20's with M261 mags in them. They needed to be cleaned for a long time. Taking the first ones out was a pain till I remembered what an old SSG told me. Use a pencil to push the rear of the M261 down. The front comes up and push it out. Going in is easy with USGI 20's, use the ones with a metal follower. Put it in then push to the rear of the 20. If the host magazine has to much play front to back make a shim out of wood or plastic flat wear. Or tweak the host feed lips (not if the magazine will use 5.56 ammo).

Now, if you can find the BD mags your set

Now, if I could just find a 1/16 pencil barrel

Thanks for the tips on getting the inserts out.

If you find the pencil 1 in 16 - let us know.

MikeS1970,

The 10 round AR Stoner mag I have is about half the length of a 20 round mag - similar to the DH 10 round mags sold by Wideners.com. Still working on this.

Ken

Thanks for the heads up!  Good to know there are other options for us.

Well, I turned the spring upside down so I could wrap it around the insert. I shoved the insert into the short AR Stoner mag from the bottom and installed the base plate.  I loaded the insert, wobbled it a little to get the front end pointed up a bit then installed it in the rifle with the M261 bolt forward.  I charged the bolt and it fired fine.  Based on this VERY LIMITED testing it appears that those folks restricted to a 10 round mag can use the M261 inserts.

I have returned the AR Stoner mag to .223 service as it is my normal target practice mag. The insert is in its normal home - an ancient Colt 20 round mag with metal follower. Perhaps someone else will take take the M261 insert testing project and run with it.

Ken