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Posted: 11/26/2010 8:10:47 PM EDT
| Hey guys. New to the rim fire conversion. Bought a CMMG stainless bolt, barrel, 25 round magazine and BHOA. I assembled a dedicated 22LR upper with the parts from CMMG but am still having trouble with the BHOA. I guess I'm not sure how it's supposed to work. I've tried adjusting the screw to move the plate up and down but can't seem to get it to work with an empty magazine loaded into the lower. With the BHOA not installed the bolt will lock open with an empty mag in place. Also it seems that my bolt hold open paddle/lever seems to bind with the CMMG BHOA installed. Other than this problem I love this kit. |
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I had to cut 2 coils off the bolt catch spring as there was too much tension. With my Bushmaster lower and my Spikes lower, the depth of the bolt catch spring/plunger hole were not as much as my CMMG lower. Tolerances vary.
Also, if the mag is new, I push a plastic rod down in the mag, working the follower up and down several times to wear it in. Like anything else new, there will be resistance until it breaks in. The binding I don't understand. If the BHOA is installed correctly, there isn't anything that should bind. |
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This is maybe a dumb qustion, but is your magazine actually a BHOA type?
The followers in the two types of mags are different. The non-BHOA follower extends past the magazine lips and locks the bolt open on the last shot (without a BHOA device). See the pics on the cmmg site. The green (non-bhoa) followers sit way above the feed lips when empty. Cmmg mags |
| Yes it is one of the BHOA mags. It has the black two piece follower. From studying how this works, with out the BHOA in place and the magazine inserted in the magwell, the bolt appears to hit the little ramp on the follower keeping the bolt open. When the BHOA and the magazine are both installed, it appears that the little ramp on the follower isn't being allowed to pop up above the tab on the BHOA. Am I wrong in thinking that the ramp on the follower is what is still supposed to hold the bolt open with both pieces installed, or is that ramp supposed to push the tab on the BHOA up and keep the bolt open? And just for clarification, this is a cmmg barrel and stainless collar, stainless conversion bolt, BHOA, BHOA mag, not sure what brand the upper is but it's a flat top, and I'm using a stag lower reciever with stag lower parts kit and a magpul BAD lever. Like I posted earlier, everything else has functioned flawless and this thing is a blast to shoot. |
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Your absolute best bet is to call CMMG and ask for Taz. Using a different upper receiver
may require some minor mods. Not even I have their level of experience with these... shaodwcop has worked extensively with them but is still in second place to the help you can get directly from CMMG.... Good Luck, Spec |
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Just a suggestion after having the same problem. Take the BAD off and see if it works then. The BAD can work fine with a regular AR, but have just enough influence to keep the BHOA from working. I also had to cut a few coils (one at a time) off the bolt hold open spring. As mentioned above, some receivers will have a slightly different hole depth and if it's shallow it causes more tension for the BHOA to overcome.
Once you get it functioning properly without the BAD, reattach it and see if it continues to work. Of course calling CMMG is the best option. |
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