Posted: 4/1/2012 3:20:15 AM EDT
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Hello. I've just purchased a new CMMG and with two seperate magazines the follower is managing to pop up past the tab on the BHOA.
Just wondered if anyone else had experienced this problem and if so what is the cure? I should say that the dealer I bought it from is looking after me but as I live the other end of the country if there is a quick fix for this I'd appreciate the input. I've attached a picture that hopefully shows up here. Never tried putting on a picture! It is a new rifle. And new magazines. Thank you in advance. http://i1161.photobucket.com/albums/q504/farmer77777/Snapbucket/4139DE8C-orig.jpg Edit: can't get the link to the picture to work. Edit edit: now working! |
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The most common issue with the BHOA not locking back on the empty mag is too much bolt catch spring tension.
If the bolt will lock back manually, the the BHOA is working. I cut 2 coils off the bolt catch spring to releive some tension. A quick fix is slipping a rubber o-ring under the bolt catch paddle to releive tension. The mag spring has to oversome the bolt catch spring. Different lowers I have tested had different bolt catch spring hole depths causing a variation in spring tension. I also adjust the BHOA by turning the rifle upside down so I can look into the mag well. Use the supplied allen wrench to adjust the BHOA by moving the bolt back and forth while turning the adjusting screw in. When the bolt starts to drag and not close completely, back the screw out 1/2 turn. Make sure you adjust the CMMG grey mags for fit by sanding/filing the two tabs on the back of the mag. Dave N |
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Thanks for the reply Dave, when I hand cycle the action - even very slowly - most times the follower will pop up past the BH tab. Do you think that taking a couple of coils of the bolt catch spring would stop this?
I'm just not shooting the mag empty at the moment,leaving a round or two in it, otherwise the follower is catching the bolt which I don't think its up to. Seems to have flattened a little bit on the rear already after happening twice with live ammo. |
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From what I hear, the Genll BHOA has a slightly shorter tab. In theory I suppose using a Genll BHOA with a Gen l mag could allow this to happen.
The Gen ll BHOA's are suppose to work with both Gen l and Gen ll mags. So if I understand correctly, the follower is moving up in front of the BHOA tab instead of pushing the tab up to lock the bolt. Correct? Dave N |
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I am not sure from the picture if your situation is similar to one I was having, but I had a situation where the magazine follower wasn't able to get far enough under the Bolt Hold Open Actuator. Consequently the BHOA ended up just slightly over-hanging the back corner of the magazine follower. The result was that the BHOA wasn't being pushed up high enough by the mag follower.
Here is what I did to fix the problem. If you look at the bottom of the BHOA, it has a small angle cut on it to make it easier for the mag follower to get under it. My solution was to very carefully modify the angle of that cut. I modified the angle with small file and made the angle longer and more gradual (ie the angle now extends further back away from the mag follower and therefore it a more gradual slope to it). Note that you must be very careful not to thin the front edge of the BHOA (in effect making that edge sharper) and you must be very careful not to remove material in a way that shortens the BHOA. You have to leave the front edge of the BHOA exactly as it is, and just extend the angle which makes the angle less steep. This makes it easier for the mag follower to get back far enough under the BHOA to be able to push the BHOA up. |