I just bought (but have not yet received) a used complete .22LR upper for an AR15 lower I am building.

I want to order some Black Dog sonic weld 25 round mags.  They have a choice of feed lips, stainless steel or nylon.  Is one better than the other, or is it like ammo, my rifle may prefer one over the other? I'd like to order today, but they have only one style feed lip in stock, so I may have to wait.

I would entertain other magazine options if offered, but BDM seems to be highly recommended based on the threads I have read here.

Upper was built with a PSA upper receiver, CMMG .22 LR Barrel 1:16 Twist, and a CMMG conversion bolt with collar.

Lower is Aero M4E1, CMMG LPK.

Thanks for the help. I am still new. This is my 2nd AR.

Don't do it. The very best magazine option for running with a CMMG style bolt are M&P15-22 mags and a Boonie Packer Better-Mag adapter. You get quality and inexpensive magazines and gain real bolt hold open functionality.

It's seriously the only way to fly.

I have both Black Dogs and CMMG's. Other than the BD's are gray and the CMMG's are black, they look indentical. Both are plastic feed lips. Never had a problem.

@Keyst0ne

Thanks for this take.  I thought I had read somewhere here that people have had hit-and-miss luck with this approach.  Can you tell me more?

Is there more than one Better Mag adapter, 'cause I am almost certain that the adapter was the issue, although maybe they weren't using 15-22 mags with it.

I like the BD mags, they run well. Plenty reliable.

I split one BD mag pretty quick after buying it, but it was replaced very quickly.  I only buy the metal lips now and have a stack of them, all thoroughly tested with my CMMG stainless rimfire conversion, and my Fostech Echo trigger.

As far as that M&P advice, a friend went through two rifles that wouldn't feed for shit and ended up getting his money back.  I was left with his MP mags and I could barely give them away.

Most of mine are metal feedlip. I tried the M&P mag thing but could never get it to run right. The best BD mag is the 32rd and with a binary trigger they're awesome.

OK, this helps.  I've spent the afternoon on youtube and forums investigating the Better Mag thing, and it seems like there are lots of problems.  Won't go in the lower without sanding corners to a more round shape, edges are sharp and cut you on install, mags don't drop free, and I'd have to take it out when putting a 5.56 upper back on the lower.  Plus, it's $50 bucks.

S&W 15-22 mags are 20$, which is the same price as the 25-round BDM mags.  So no savings there.  The spring hold-down feature is nice, but with a McFadden loader (which is way less than the $50), the BDM mags would load in a flash.

Plus the 32-round BDM mags have the hold down, so there you go.  Those mags are $30 at BDM. That $10 increase can be paid 5 times with the $50 I don't spend on the Better Mag adapter.

If the lack of LRBHO bothers me, then a Catch-22 bolt catch is a lot less than $50.  Of course, that is an installation as well, and something that needs to be taken out if I go back to a 5.56 upper, so that's a wash with the Better Mag.

First world problems.

I would still like to hear any and all opinions.

I'm not here to talk you into anything you don't want to do, but I'd encourage some perspective.  I've never read about anyone's magazines not dropping free with the BMA and S&W magazines, though I have read that from people who didn't know they were supposed to file and fit their CMMG magazines to fit their magazine wells.  The BMA does have some very sharp edges, but if you observe them you should be able to avoid cutting yourself.  Yes $50 is a lot, but the BMA spreads stresses out in a very smart way and allows easily reversed and very effective LRBHO.

I prefer the Catch 22 solution because I have a dedicated 22lr lower, but I'd never suggest that a BMA is a mistake.



In normal market conditions, the S&W magazines are between $10 and $15.  You should know that while great in many ways, S&W 15-22 magazines have a life.  I get several thousand rounds from each of my short 10 round magazines.  They are consumables.



Catch22 now has an easily removable catch that fits onto the existing AR bolt catch.  It appears to be sold out at the moment.

https://arcatch22.com/products/catch22-v2-bolt-catch

Have you ever used a BDM 32 round gen II magazine?  I've read complaints about weak feed lips and the spring not being strong enough to work a LRBHO.  I've used one though.



A magazine free bolt hold open is a big deal to me because I shoot at public ranges.  I like a working LRBHO and bolt release for reloading while in position.  It makes life a little easier.

Same here and I've used them on a few registered receivers

The nylon Black Dog magazines work well in a couple of our rifles but the stainless work well in all of them.  
My PSA upper does not like the nylon feed lips, it has FTFs.

The mag loader on their website works very well and is worth the cost.

I have one CMMG that came the conversion kit and a couple Black Dogs- with plastic and metal lips,  and they work great.

i started using black dog mags way back when they came out i still have several gen 1 skinny 30 round mags anytime i have had a problem with a mag cracking they have replaced it for free i even have 3 of there drums 1 for my 10/22 and 2 for my dedicated  ar22 with a ciener 22 kit
i even sold of all my preban ciener metal mags to switch to bd mags and would do it again

I have two metal lipped Black dog mags and 2 older grey plastic lipped CMMG mags. All four run flawlessly with no problems.

I have a ton of gray cmmg magazines, and I have never had to file a single one to make it fit. BD mags, the steel feed lipped are great.

This is gospel

I recommend that as well as higher capacity mags, regardless of brand and/or style, you also get a couple 10 or 15 round, small (i.e., less tall) body mags.  I think only Ciener, S&W, and BDM sell them, but I am open to correction.  There are occasions when the small body mag is handier (e.g., shooting prone or on a bench); and I use them almost all the time in my AR-15 .22 pistol.
Best of luck whatever you pursue.
MHO, YMMV, etc. Be powerful and be well.

So I have tried all the options that have been discussed in this thread.  CMMG bolt with CMMG mags and then BD mags - worked! The issue here is the bolt will close when you remove mag but it does signal empty gun and you can engage the bolt catch if you want it to remain open. By far simplest system.  Next the Catch-22 V1 bolt catch - My lowers are dedicated to the 22lr uppers so installing the Catch-22 bolt hold open was no problem.  The new Catch-22 V2 system that can be mounted to the standard AR-15 catch eliminates the multiuse lower issue.  Have not heard how reliable the V2 system is?  Another note the Catch-22 works with MP15-22 mags, CMMG and BD mags.  To run the MP15-22 mags you will need the MP15-22 mag adapters. I like the stick on model as I do not have a MP15-22 rifle to use the M&P mags with. Have used the clip on adapter also and it works the same.

The Better Mag system has given me the most problem being 100% reliable.  Other's experience may be different - this is my experience. The MB adapter needs to match up with your lower and you may have to make some adjustments to the adapter.  I will say I did not have to adjust anything to mount the BM system, slid right in!  

The Catch-22 V1 is the unit I currently use.  I have also added the Lightened Bolt Catch Spring, which helps reliability. If I would do it again from start and have the experience I have now, I would just run the CMMG mags until they wore out or failed and then replace with the BD mags.  The bolt closing after removing the mag is not a big deal to me and the bolt catch can be functioned if the bolt needs to stay open. Just like my 10-22s. This experiment has cost close to $200 with all the additional mags and adapters and from experience that $200 would have been better spent on 22lr ammo, if I could find some - LOL

Also if you stick with the CMMG/BD mags, buy the Mcfadden Machine loader - cost of a M&P mag and still way faster than hand loading the M&P mags.

I have made no final decisions, but I did order a few BD mags yesterday and the McFadden loader.  If they are reliable, no need to go further.  If they are not, I will try to acquire a S&W 15-22 mag, and the Catch-22 clip on spacer.  Beyond that, if the LRBHO is an issue, I'll go with the Catch 22 V2 bolt catch. Talked to the Catch 22 folks via email, and they were both helpful and responsive.

The Better Mag adapter really doesn't interest me.  The upper is dedicated, the lower is not, so installing and uninstalling the Redi Mag adapter (or the Catch-22 V1 bolt catch) is not something I want to get into.

I have both the BD metal and plastic feed lip mags. Both work great. McFaddern loader is a must. Also buy the BD 50 rounds drum if you can. They are great.
Better mag adapter works also, I have one and never use it anymore. FWIW

I have the CMMG 22ARC bolt assembly with one of their barrels . I went the Boonie Packer way at first but found the Catch 22 Mag catch for the S&W M&P15-22 mags better I prefer the S&W mags) - I also added their small Delrin stick-on pads on the mags to keep them tight. I like the pads better than the Magazine Adaptor clip.
https://arcatch22.com/

Also, this may be of interest
https://www.rimfirecentral.com/forums/showthread.php?t=1134191

@WSAR15 - Thanks for the post.  I checked out the link, and read that thread.  I have bookmarked that site, it was new to me.

If I may ask, why do you prefer the stick on pads to the clip that goes on the front of the magwell?

You're welcome. I spent a bit of time researching this and as not aware of the Catch 22 unit until a few weeks back.
The clip is simply a polymer clip that fills some space inside the mag. It clips over the front magwell lip. I works and is more cost effective. It is easily removable and leaves the S&W mags in their original state which is useful if you also have an S&W rifle. I like the S&W mags in terms of quality, reliability and availability, so I decided to go this way (and I had the Better Mag unit from year ago and just recently assembled the rifle). I have 10rd and 25rd S&W mags.

I found the small adhesive pads, mounted at the upper part of the mag to be a better fit and perhaps more reliable overtime than the clip. I found the clips with the pads a bit harder to insert than with the clip. The pads fit on easily and seem to hold well.

All this said, I have never tried any other mags such as the Black Dog or CMMG which may be fine as well or even better.
I have a 22LR 16" M4 type barrel on order at CMMG and will assemble a second unit on the same basis in due course. By the way, I am also installing the Taccom Pressure Plug.