RRages has the limited mags and they also have the uppers in stock.

 

I was under the impression that the CMMG 22 uppers came with the BHO feature. Is that wrong? Do I have to add the arcatch22 to the CMMG upper to get the last round hold open to work?

 

To use the M&P mags, you need the catch22 adapters and bolt hold open. For the new CMMG evolution mags, you need the CMMG bolt hold open adapter. It is ordered seperately from the upper.

The CMMG EVO BHO device is a separate part and actually attaches to your lower so the CMMG mag follower can activate it. There's no room in the upper for any extra dongles, only the bolt itself. When the mag is empty, the follower pushes up on the CMMG BHO "block", which then gets in the way of the bolt and holds it back. Then, when you remove your mag, the BHO block stays in place and your bolt is still kept locked back. It only works with the CMMG brand mags though, however, there's probably no difference in the bolt itself since the CMMG bolt is just another Ciener copy. The BHO could work with other similar Ciener copy bolts, but dont quote me on that.

 

http://cmmginc.secure-mall.com/item/BHOA-Adapter-Assembly-1525

This BHO is starting to not be worth the hassle

BlueLineFish, did you ever get the conversion? I'm curious as to how reliable it is.

I did recently. Havent tested it yet though

Ok, I'm interested to see how you do with the bulk pack ammo if thats what you're planning to use.

So I have one of the Evol mags from CMMG and it holds the bolt open after the last round, but it closes after you remove the mag. I bought the BHOA and when it's installed I have feeding problems. I have tried to adjust the BHO but no luck getting it to work correctly. I am thinking with the BHOA the standard bolt stop will be pushing up on the BHOA to make it work? I would guess that after you finish a mag the bolt stays open using the BHOA and not the mag follower? The only extra function I get with the BHOA is that I can use the standard AR bolt catch. The bolt still stays open by the using the mag follower and not the BHOA after the last round. If I am correct in my thinking that the BHOA only adds the ability to use the standard bolt catch? If so I don't need this! My CMMG upper has been great without the BHOA and using CCI mini-mags. I haven't used any other ammo as CCI is all I will buy, I love shooting this thing and hope to have clean runs on Sat at OBRAMS!!

That bhoa from cmmg is a tricky little thing trying to get it adjusted just right. I gave up, it's not really necessary anyway. I have my upper running 100% using federal bulk. The only problems I ever had with it were an issue with the safety randomly engaging but, that was an issue with the pistol grip. The hole for the spring was drilled too deep. Also, if I load the mags to their 15 round capacity, I will get fail to feed issues on the first round. I just load to 14 and have no issues.