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Posted: 7/28/2009 4:46:18 AM EDT
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I'm assem. a CMMG 308 lower & when I used my other DPMS upper to see how they matched up ( I plan on using a DPMS upper on this build also ) I came across some thing I didn't expect, as you will see in the photos. The upper will only hinge or pivot just enough to remove the BCG & I mean just barely . So I e-mailed CMMG & informed them of this . I had already removed some material to let the two receivers swing or pivot farther for several reasons ,one I have never encountered a limited pivot on any AR platform I have built ,two , I kinda like to see & inspect my internals with out having to remove the upper , three ,I think if they incorporated a real stop & not a friction fit to stop the pivoting ,I might have let it go , but in the case of the upper I was using to fit ,it has a 20" HB and is on the heavy side . I did not like that much pressure on those small pivot points in the lower . Below is there response and photos . I would like your opinions . The last photo shows max amount of pivot.
That is correct. You should just be able to remove the bolt carrier; any
extra travel is not needed. This will also keep people from squashing there fingers between the upper and lower or damaging handguards and receivers. Thank You, Garson –– Technical Support CMMG Inc. P.O. Box 369 Fayette, MO. 65248 660-248-2293 ext. 73 660-248-2290 Fax 
 
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CMMG's response seems to indicate that this is "As Designed" and they don't feel it's a defect. If that's the case, you have two choices:
1. Modify it to behave the way you want it to behave. Perhaps additional lubrication will loosen things up a bit. 2. Leave it as is, and if you want to do more than remove the CH/BCG, knock the pivot pin out. I wouldn't be overly concerned about any extra stress on the pivot point, as that will only be vulnerable during maintenance and cleaning operations. Unless, of course, you make a habit of carrying your weapon around like that. 
You may want to try posting this over in the AR Variants forum for more opinions. Sorry if this appears to be a smart ass response. That's not my intent. -Ty |
| I have already modified it to my spec's as per photos. I posted as to see if anyone else has a CMMG lower that is like that . I kinda believe there (CMMG )response , it may well be as designed or it could be just covering there behind because of a missed finishing procedure & it will work ,so they pass it on. I don't view your remarks as smart ass , I asked for opinions & would have taken any ,any way they came . I will post it at the Variants forum ,I just haven't got around to it yet. A little alum black & ya never knew any thing was done. |
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