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Posted: 7/29/2009 4:59:50 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. I touched the bare metal up with aluminum black & oil ,looks like it was made that way. Does any one have a CMMG & is yours set up to pivot this way . It could be designed this way or it could be just a company covering there own behind because of a missed procedure .This is a Quality lower ,can't wait to get it all together.
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 hand guards 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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What I would like to know is ,is any one Else's like that ,the way mine was . Who has CMMG lowers that have a restricted pivot ? I like this lower it has some nice features and is a quality piece . If you look at the one photo ,it shows the my DPMS lower on the left & the CMMG on the right . You can see the CMMG is much beefier in the pivot ear area.
There was also another thing that was missed in manufacture or QC , the pivot pin spring/detent hole was plugged up with metal debris from machining . The spring/detent would not fit,too shallow, I had to use a proper sized drill bit (by hand,well ,fingers ) to auger the debris out of there ,it was impacted in there (almost a 1/4 " ). A very minor thing ,but you have to under stand ,I didn't have to do any thing to the DPMS. You do some times have to do minor fitting to unmatched uppers& lowers, just part of the process. |
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