View Full Version : CMMG/JD Machine .308 G3 Upper and Lower receivers!

12-01-2009, 8:45 PM
Since for some odd reason CMMG never produced an upper receiver compatible with their cool billet .308 lowers that use the HK G3 mags, we decided to tackle this problem ourselves.

RifleGear.com has teamed up with JD Machine to bring you upper receivers for the CMMG G3 Lowers! We have these in stock and available as individual uppers/lowers or as a matched set that includes two new G3 magazines. We will block the magazines to 10 rounds for CA customers.


CMMG/JD Machine G3 Matched Set (http://riflegear.com/p-668-cmmg-g3-mag-receiver-matched-set.aspx)

CMMG G3 Lower (http://riflegear.com/p-611-cmmg-mk-8-billet-g3-mag-compatible-308-stripped-lower-dpms.aspx)

JD Machine G3 Upper (http://riflegear.com/p-626-jd-machine-billet-upper-receiver-762x51-g3-mag-compatible.aspx)

12-08-2009, 8:20 AM
I just noticed your icon has a christmas hat on. lol.

12-21-2009, 2:54 AM
Hi Riflegear,

Bought a few things from you folks, great service, fast shipping....thanks:thumbsup:

Had a few questions for you about the CMMG/JD Machine .308 G3 Upper and Lower receivers:

How is the quality/finish of the upper/lower?
Reliability of CMMG/JD machine products?
Since the upper is just the receiver, will it work with the DPMS barrels, bolt carrier group for the AR-308 (specifically the 18" .308 Fluted Bull Barrel w/Gas Block & .308 Chrome Carrier w/Phosphated Bolt)?
You have better suggestions for the barrel, gas block/system & BCG?
Can you recommend someone to properly head space the barrel?
Also, does this set-up have the bolt hold open on the last shot?


12-21-2009, 9:06 AM
1. Great
2. Consistent and great
3. Yes... after all its a DPMS pattern receiver... it will work.
4. These days? whatever you can get your hands on.
5. Buy your parts from reputable companies. If you mean check the headspace, not sure who has 308 gauges.
6. The G3 receiver does not have a bolt catch. The other CMMG 308 receiver we have in stock does and takes DPMS magazines. It will also work with this upper receiver.

12-23-2009, 4:40 AM
I am new to the site.....I just have a few concerns...

I bought a (CMMG .308 lower G3) a few weeks ago and have been working with a gun smith to put it all together and we have come up with a problem..

He has one of your JD uppers and it seems to not be machined right...we were putting it all together and the HK mags seem to not fit the upper when its assembled.. He told me he spoke with one of your reps at a gun show and he said that you folks at riflegear were aware of the problem...

do you have any input???......was looking forward to building this .308 but it seems that many folk have been having the same issue


12-23-2009, 10:23 PM
I am not aware of a problem with the uppers, they were machined by JD specifically to allow clearance for the G3 mags. Who did your gunsmith speak to?

12-23-2009, 10:46 PM
i'm not sure who he spoke with.....I am supposed to meet up with him tomorrow for another build that he is working on for me..... I will be sure to ask him and I will get back to you....