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StrangeBrew
04-28-2008, 1:07 PM
There are a few markings on lower receiver that I am curious about. One looked like a crack at first but after further inspection I am guessing its just a machining mark. Anyone else have a CMMG lower that has similar dings and lines on the finish?

ITs hard to see because of the poor pictures, but its a line that goes down to the pin next to the mag release. Also there are tiny dings and scratches on the receiver but they are hard to see in the picture. I am assuming I have nothing to worry about, I am just curious if most CMMG lowers have these marks.


http://i94.photobucket.com/albums/l92/Elcommando_2006/Picture083.jpg
http://i94.photobucket.com/albums/l92/Elcommando_2006/Picture086.jpg
http://i94.photobucket.com/albums/l92/Elcommando_2006/Picture085.jpg
http://i94.photobucket.com/albums/l92/Elcommando_2006/Picture084.jpg



Also, sometimes when I hit the bolt release the bolt doesn't manage to feed the round all the way out of the mag and into the chamber. I don't think its a magazine problem as it happens in all of them. Is this a common problem?

Thanks

mikecro1
04-28-2008, 1:25 PM
There are a few markings on lower receiver that I am curious about. One looked like a crack at first but after further inspection I am guessing its just a machining mark. Anyone else have a CMMG lower that has similar dings and lines on the finish?

ITs hard to see because of the poor pictures, but its a line that goes down to the pin next to the mag release. Also there are tiny dings and scratches on the receiver but they are hard to see in the picture. I am assuming I have nothing to worry about, I am just curious if most CMMG lowers have these marks.Thanks

man for a minute...I was wondering how you got a picture of my lower????:D funny enough, mine has the similar mark at almost the same spot:eek: ....nothing to worry about...scars give to personality to things....just look at Tony Montana!

Heavy_Grinder
04-28-2008, 1:48 PM
There are a few markings on lower receiver that I am curious about. One looked like a crack at first but after further inspection I am guessing its just a machining mark. Anyone else have a CMMG lower that has similar dings and lines on the finish?

ITs hard to see because of the poor pictures, but its a line that goes down to the pin next to the mag release. Also there are tiny dings and scratches on the receiver but they are hard to see in the picture. I am assuming I have nothing to worry about, I am just curious if most CMMG lowers have these marks.



Okay, now you got me wondering. Need to go home and take a look at mine.



Also, sometimes when I hit the bolt release the bolt doesn't manage to feed the round all the way out of the mag and into the chamber. I don't think its a magazine problem as it happens in all of them. Is this a common problem?

Thanks


As for your second problem about the half chambered round (Bolt Release)....I havent got a clue. What kind of upper do you have?

I have a CMMG upper and lower mated together and whenever I let the bolt fly, It chambers a round with significant force everytime.

ty423
04-28-2008, 1:52 PM
I think thats when the forward assist comes into play when the round doesn't fully go into battery.

vega
04-28-2008, 1:59 PM
man for a minute...I was wondering how you got a picture of my lower????:D funny enough, mine has the similar mark at almost the same spot:eek: ....nothing to worry about...scars give to personality to things....just look at Tony Montana!
If you made the scar yourself then that's personality. If it comes from the factory I'd say that's factory blemish, IMHO.

shark92651
04-28-2008, 2:07 PM
You shouldn't need to use the forward assist in this situation. Both of my first two builds exhibited this issue where the tip of the first round was hung up on the feed ramps, . If you continue to fire the weapon it should break in and be fine. Make sure you are slapping that bolt release so it releases with full force. Also, you may want to every so slightly bend up the feed lips on your magazine so that the tip of the round has a better angle. With use this problem disappeared on it's own on my rifles.

5150Marcelo
04-28-2008, 2:18 PM
mines flawless... actually very impressed how clean it was.

mstngcbra42
04-28-2008, 3:28 PM
I recently purchased an AR-15. I experienced my mag misfeeding similar to what you mentioned earlier. I sent the Rifle back to Stag Arms and had it repaired. Cause of the problem ended up being a bent buffer tube on which the bolt carrier was dragging. Ill be testing it out this comming weekend. We'll see if problem has been solved.

Eric_Oh
04-28-2008, 4:15 PM
I'll go home and check mine... but i don't recall seeing that on my lower.

cseabass
04-28-2008, 4:40 PM
sounds like a mag issue. as for the mark... i don't know.

Eric_Oh
04-28-2008, 9:19 PM
jus checked mine... nope. No visible mark or crack or anything on mine. Strange.

elSquid
04-28-2008, 10:14 PM
I have 4 CMMG lowers. Each has the mark: I never noticed it before, but it's there. Serials are in the mid-5000s range, SA prefix.

2 of my lowers were actually in the bubble wrap in storage. When I pulled them out and took a look, the side of one had lots of light scratches - like it had been dropped and slid across a semi abrasive floor. I guess I should have inspected that one better before buying it. Oh well. Such is life.

-- Michael

elSquid
04-28-2008, 10:23 PM
Ok, I managed to figure out how the macro function works on my camera. :)

http://sqidbait.googlepages.com/cmmg005.jpg/cmmg005-large.jpg

-- Michael

StrangeBrew
04-28-2008, 10:58 PM
Thanks for the replies guys. I find it very interesting that a few of you have the same markings on the receiver.

As far as the problems stemming from not being broken it, I have shot around 200rnds through it so I think its decently broken in. If it continues to happen after a few hundred more rounds and different mags, I will be worried.

This is what someone at Ar15.com told me could be wrong with the feeding problems.

As for the rig not charging. going to guess that the tip of the round just start up the barrel feed ramps and that's it.

Looking at the hammer, it appears that the FP collar is catching the hammer. Pull the B/C and take a look at the FP against the carrier ramp. The FP collar should be slighty below the ramp, not riding//seating higher than the top edge of the ramp. If needed, chuck the FP up in a drill and spin file the stop collar edge to reduce it the needed amount.

Sydwaiz
04-29-2008, 8:42 AM
Relax guys, it's just a forging mark. Probably a blemish in the forging die. The outside of these things aren't machined except to remove the forging flash. Those of you with the same mark have lowers that came from the same forging die.

PoodleShooter
04-30-2008, 2:27 PM
I have the same exact mark on the lower of my 14.7 SOCOM. The serial is number SA0256X... I purchased it Fall of last year. There is also a small pinhole sized dent above the forward assist pin, right behind where the upper forge marking should be (which is absent on my upper, unlike on other CMMG uppers I've seen which have the keyhole marking). No big deal, really.

Something that did bother me about the rifle: It came with a bad magazine catch assembly which I had to change out. It came apart (the pin separated from the catch, causing the spring and button to pop out) while I was inspecting the weapon.

Other than a bad mag catch it's been flawless after 1500 rounds. For $815 I'm very pleased with it.

I attached a photo of the "scratch" and a pic of the faulty mag catch assembly pin. The new mag catch is the one installed.

tophatjones
04-30-2008, 6:57 PM
I've got one with the same mark. No problems at all so far. Btw, have you checked that your barrel is perfectly aligned with the upper? If not, this could hang up bolt lockup slightly.

Sydwaiz
05-01-2008, 10:24 PM
Just thought I'd let you know my DoubleStar receiver has the same mark. More proof that they are the same except the logo (and the price).

PoodleShooter
05-02-2008, 1:03 PM
Yep you're right - I saw a DS lower on GB that also had the mark.

http://gunbroker.com/Auction/ViewItem.asp?Item=98831028

(in the 2nd photo it's clearly visible)