Hi guys, long time lurker first time (probably) poster. Just finished up my first dedicated 22LR, and I’m hoping I have a dumb ‘problem’, from a lack of ar22 experience. The build is a dedicated CMMG arc bolt, Beyer barrel, stripped M4e1 enhanced upper/lower/hg, SOLGW LPK blaster guts, velocity 4lb steel case trigger, Geissele SCH and part of the Borebuddy reliability kit (bolt weight, buffer plug, buffer pad).

I’ve read more threads than I can count on BDM mags being awesome or the boonie packer set up is the way to go, so I apologize in advance, if this has been covered, but I didn’t see it. Specifically, my problem, while function testing, I can’t get the 32rd mags (3 of them) to seat/lock in…there appears to be about an 1/8” of interference somewhere…I’m seeing witness marks on the feed lips. The mag locks in with the lower separated from the upper, I can pull the rear pin, lock the mag in and close the upper with no problems. But I can’t load and lock a 32rd mag with everything together. I pulled the Borebuddy parts, thinking maybe too much positive pressure or stacking tolerances caused some sort of misalignment…nothing changed. The 25rd black dog mags operate perfectly…nylon and steel feed lips. I tried 3 other pretty well worn (10,000+ rds each) 5.56 dedicated lowers, thinking maybe things would be better when loosened up, but same results.

With as well as everything else fits/works together, and the fact I can close the upper on the 32rounders and get the desired results, I’m thinking I have to be overlooking something simple. This will primarily be a plinker/trainer for my 5 year old (and my other daughters as they get older), so the option of relieving some mag tension while loading would help save her/their thumbs. Can someone help a guy out? Thanks in advance.

Will they load on an open bolt?  Not sure why you would have to separate the halves.  Easy answer just seems to be to use the 25's.

I knew I forgot something…no they won’t load with an open bolt…and I can’t see any interference with the bolt open either. And the simple answer is use the 25rounders, but it just seems like I have to be missing something, after not seeing anyone else having the same issue. If it is a simple fix, I’d like to be able to use the 32rounders for the kids.

The 32 round BD mags are not made for the current CMMG bolt. Stick with the 25s and all will be fine.

Black Dog Machine make two different 32 round 22 LR magazines with steel feed lips.   One type of 32 round BDM mags is designed to work with Colt 22 AR-15 conversion unit which also work with DPMS Gen 1 dedicated 22 LR upper and conversion kit.   The magazine for the Colt/DPMS has an ejector built into the non ejection side feed lip.   The ejector on an Atchisson/CMMG pattern bolt is incorporated in the bolt rail.   If you have the Colt/DPMS pattern mag that would explain why it won’t work in your upper.  

Here is a picture of the BDM 32 round Colt DPMS mag.  Notice the inside feed lip has a raised portion at the rear of the feed lip, that is the ejector.  If your 32 round BDM Mags have the ejector they are not compatible with CMMG 22 dedicated upper or 22 conversion bolt.   BDM does make a 32 round mag of similar appearance that does work with the CMMG/Atchisson pattern bolt.

L-R BDM DPMS/Colt 32 mag, BDM Gen 1 25 round CMMG mag, BDM CMMG 15 round mag, AR-15 20 round aluminum mag, DPMS Gen 1 ten round mag.




Here is a link to the BDM 32 round magazine designed to work with the CMMG/Atchisson pattern 22 LR bolt.


https://www.blackdogmachinellc.net/3rd-generation---metal-feed-lip-magazine-for-ar15-22-conversions.aspx

Thank you for the info. So if I’m reading your post correctly, the mag in the far left of your pic is what does NOT work with the CMMG bolt, which does look like mine.


Are you using the ARC bolt? If not I suppose MN @hdcharlie might be right…but still seems odd i can drop the upper on the mag and ‘fits’, but I can’t load normally.

Split the last post…Limited to 2000 characters…

But for someone smarter than me, this is the exact mag I purchased:

https://www.midwayusa.com/product/1006319365?pid=541257&utm_medium=email&utm_source=service&utm_campaign=shipping-confirmation&utm_content=product-shipped-today-product-description-link

The feed lips on the mag you pictured do not appear to be the right ones for the newest CMMG bolt. I don't think either of the BD 32rd mags are made for the newest CMMG bolt, but I would check with BD to be certain.

Thanks…just sent them a note.

The BDM mag you linked to is the same magazine I linked to on BDM website.   Your magazine is probably correct as long as it doesn’t have the little ejector tap on the mag feed lip.   I haven’t used the BDM 32 round mag for the CMMG/Atchisson/Ciener pattern bolt.  I only bought the 32 round BDM mags for my DPMS dedicated uppers and my Colt 22 conversion.  


You could have a tolerance stacking issues where the mag sits to high in the mag well.   When my 32 round mags were new the mag spring was pretty stiff and you needed to use the pull down tabs and properly load the mag.  I would just move the follower down enough to load one cartridge at a time.   If you pulled the follower via loading tab down a ways then tried to drop fresh cartridges in the mag the cartridges failed to feed.   Rimfire cartridges need to stack properly to function from the magazine.


If you can post pictures that always helps.

I do have pics…and planned on posting…not sure if I’m too new or have to become a member. But I don’t host them anywhere, is there a hosting site that works best here?

I use imgur, but there are others.

Well...they didn't say the mags didn't fit...just that it hadn't been tested. But I have to assume, an answer that isn't a resounding 'yes', is a pretty strong indicator. Kudos to them willing to make the swap.

I have 2 BDM mags and they don't work for shit.  S&W mags are the way. So much easier and quicker to load.

I may end up going that way after I put a few hundred/couple thousand rounds through this set up. You know how it goes, spiraled down a rabbit hole...originally thought I was just going to snag a Nordic (or JP) upper and have some plinking fun, and it spiraled from there. Changed my mind a half dozen times and ended up with spares and extras...so naturally that means something new needs to be started.

Thanks for the info and pics.

I too have a couple of the 32rd mags which don't want to seat in an AR lower with CMMG-parts built upper. I always just figured it was my M-16 lower being a little out of spec and never cared all that much since the BD 50rd drum was just as easy to load and held more rounds.

I'll need to get the mags out and see if they are the ones with the metal ejector tab up top.

If so I might contact BDM to see about getting them swapped, but I probably bought them 8+ years ago and just put them under the bench when I discovered they didn't work but the drum did....snot sure I'll have much standing asking for a refund/swap out

If you find out you have the 32 round mags for the Colt/DPMS and BDM won’t switch them out let me know.   I only have two 32 round BDM Colt/DPMS mags.   The Colt 22 conversion and DPMS Gen 1 uppers don’t come up very often in conversations on gun forums these days.  

Will do.