View Full Version : 10 round BDM mags and BHOA

05-04-2011, 7:57 AM
Well, I discovered something. I have been telling you guys that the BDM mags would work with the BHOA, only requiring you to manually lock the bolt back on the last round.
It does not work. I have not been able to figure out the difference in the mag bodies but obviously there is something.
The CMMG standard mags work fine using this method.
I even tried using the CMMG standard followers in the BDM mags. No joy.
The last round gets FUBAR'd every time.
I do know when I tried to mod the BDM mags to use the CMMG BHOA follower, the feed tower itself was too tight and had to have material removed from the back.
Sorry guys. The uppers will work fine with BDM mags but not with the BHOA.
Hopefully, CMMG will get these new mags out soon for you guys.
Keep the BHOA's. Just don't use them with the BHOA mags. It will jam on the last round.
Again, I should have checked into it further before making the recommendation.

Update--Member Cyclepath has developed a mod to the follower, shving the rear of it down. It seems to have corrected the problem. Hopefully he will see this post and give a detailed discription.


05-04-2011, 10:04 AM
I bought the BDM magazines and the BHO device. I haven't bought followers and rely on the regular followers to act as a "stop" on the last round requiring the bolt to be pulled manually to the rear and BHO set by hand. Even without the automatic BHO feature this is a benefit at the range, being able to lock to the rear and show the gun as empty.

The BDM magazines have worked fine for me however, the tail end of the follower can press against the front of the device's BHO tab. Perhaps this has an effect on feeding, it can result in the bolt closing (after being manually locked) when the mag is being removed. Instead of dressing down the follower I dressed down the front of that BHO device tab - just a bit to allow the follower to pass in front as it feeds rounds and to have no contact when the mag is being removed. Again, I removed just a touch with a small, fine file and have had no failures to feed on the last round nor accidental bolt closure when removing. I think I'm going to be content to have the follower act as the stop on the final round, manually lock to the rear.

With all the unit's positive attributes, heck - I can live with doing it by hand.

05-04-2011, 11:32 AM
I am waiting for this.....

Looks very promising.


05-04-2011, 11:49 AM
Interesting but I'm not sure it would work with a 5.56
Dave N

05-04-2011, 11:50 AM
This may not be the case with all BDM mags. The few I have are gen 1's without the bolt hold follower.
Dave N

05-04-2011, 2:40 PM
Interesting but I'm not sure it would work with a 5.56
Dave N

I think it would not - the piece of metal retaining the BCG looks fragile & has a 90 degree angel - I know sharp angles don't like stress, but it looks like a neat set up for the dedicated rimfire set up. I'm wondering how that tab stays out of the way of the bolt if the bottom of it is being raised by the tail end of the case - seems high enough to get in the way.

05-04-2011, 2:42 PM
I agree. Nice concept if they pull it off.
Dave N