PDA

View Full Version : checking out a used CMMG AR15 tommorow, what should I look for?


xdanxx
05-08-2011, 12:11 AM
A friend of mine is looking to sell a complete CMMG AR15 for around $600. I plan on checking it out tomorrow, what should I look for? Im a little weary of CMMG, seems like bargin bin guns.

Any tips on what to look for, ask about, and pricing?

thanks.

rodeoflyer
05-08-2011, 12:28 AM
careful what you wish for - the potential responses you are going to get will likely bring further confusion lol.

Check out the barrel like any other rifle - shiny bore, good rifling, no pitting, etc.

Strip the bolt and have a looksie - is everything clean and look like you would think it should? Does the extractor have a good ridge on it? There's really not that much to worry about. Frankly, an entire new BCG (bolt carrier group, assuming you don't know AR's) is around $100. If you had to replace it you'd still be doing good.

There's really not a whole lot to it. If the barrel is good and the rifle is functional, $600 is a damned good price.

1forall
05-08-2011, 12:42 AM
You should...find a local dealer and purchase a different rifle.:hide:

negolien
05-08-2011, 1:01 AM
Ohh deffinatly break it down right there on the spot bud for sure. I made the mistake of taking someones word for "alls good" yeah I wish lol. The FCG was dremmeled or shaved or something was just not right. I tore it apart like 15 times thinking it's backwards spring or something. After every shot u'd have to bump the trigger or safety selector switch. It did this regardless ofif safety was in or not so wasn't that either. I wasnt sure if it was the cheap part or not so I got a SD3Gun Cost me $170 .

Soooo only way I could tell this was A. shoot it or B. break it down and hand cycle the hammer just like as if it were being fired including resistance. That and the Magpul front sight won't sit on the aftermarket gasblock and still close. Other than that I think it was issue free ROFL.

mrvash
05-08-2011, 1:31 AM
I have a CMMG complete rifle and love it! It's my "go to" rifle, two-thousand flawless rounds and still going strong. Like everyone says, break it down before you commit to purchasr.

FailedAngrMgmt
05-08-2011, 1:51 AM
like any used gun, check it out like everyone else suggested, that being said, i wont be getting rid of my CMMG anytime soon.

negolien
05-08-2011, 2:25 AM
and I concur that $600 is a good deal depending on age and use. That's what I paid for mine and probably because he broke the FCG and couldn't figure out waht was wrong? lol who knows. Was almost spotless I did replace some items for upgrades of course. Wish I had a camera so I could shoot some current pics.

Capt Jack
05-08-2011, 7:00 AM
If you can, shoot it before you buy it. No, its not a Colt, but CMMG is decent quality IMO. The upper is where the magic happens. As others have mentioned, take a look at the BCG and see if its staked well. You can always replace that if you need to. Get a light down the bore and see if its good. The lower half is pretty standard stuff across most manufacturers. Do a function check and you should be gtg.

If it was me and the gun was in good shape, I would consider $600 to be a good price. Good Luck! Oh, and just because, here's my CMMG mid-length on a RRA lower. No fail to anything since I've owned it and it would be the first thing I grabbed if a zombie was knocking on my door :43:
http://i203.photobucket.com/albums/aa275/Gr8fuljack/img144-2.jpg

dieselpower
05-08-2011, 8:33 AM
Look for the barrel to have "CMMG 556 NATO 1:9" either stamped or electro-etched on it. If it says "WASP" that is a real good thing.

The upper should have a keyhole, square or Cardinal symbol on it right behind the shell deflector, the absence of a symbol or a letter is suspect but not unheard of for CMMG.

Tap the delta, Plastic or metal? CMMG has never used plastic...very good indicator of a cheap Blackthorn upper. Blackthorn now uses metal, but little things like that can still be found.

Look at the feed area. Do a google search for "M4 feed ramps and Normal feed ramps" the picture you find will tell you what to look for. You are making sure someone didn't mis-match a lower and upper. A Factory rifle will never be mis-matched..its one way or the other.

hope this helps

coma13
05-08-2011, 8:38 AM
Taking a tiny LED flashlight is always helpful for me to check the condition of the bore.

Dannicus
05-08-2011, 8:43 AM
Also check for galling Al on any metal to metal areas. Running dry ruins the surface. Galled surfaces won't carry lubrication well.

missiontrails
05-08-2011, 9:20 AM
Look for the barrel to have "CMMG 556 NATO 1:9" either stamped or electro-etched on it. If it says "WASP" that is a real good thing.

The upper should have a keyhole, square or Cardinal symbol on it right behind the shell deflector, the absence of a symbol or a letter is suspect but not unheard of for CMMG.

Tap the delta, Plastic or metal? CMMG has never used plastic...very good indicator of a cheap Blackthorn upper. Blackthorn now uses metal, but little things like that can still be found.

Look at the feed area. Do a google search for "M4 feed ramps and Normal feed ramps" the picture you find will tell you what to look for. You are making sure someone didn't mis-match a lower and upper. A Factory rifle will never be mis-matched..its one way or the other.

hope this helps
Do certain companies really use a plastic Delta ring? I have never seen such a thing....

xdanxx
05-08-2011, 9:21 AM
Look for the barrel to have "CMMG 556 NATO 1:9" either stamped or electro-etched on it. If it says "WASP" that is a real good thing.


it was to my understanding the WASP lined barrels were actually cheaper and less desirable then the chrome lined ones, is that not the case?

thanks for the tips everyone.

missiontrails
05-08-2011, 9:21 AM
You should...find a local dealer and purchase a different rifle.:hide:

For $600?

missiontrails
05-08-2011, 9:25 AM
it was to my understanding the WASP lined carrells were actually cheaper and less desirable then the chrome lined ones, is that not the case?

thanks for the tips everyone.
You know what's funny about that? LWRC does not chrome line their barrels, they use a black armor finish inside and out that is very similar to WASP. What makes the WASP barrels less desireable is the fact they are 4140 1/9 commercial grade barrels. I personally think a normal CMMG 4150 CMV barrel with WASP would be pretty cool.... maybe a little more accurate than a chrome lined one.

WASP = Weapons Armament Surface Protection .............or something close to that.

Z.1
05-08-2011, 9:30 AM
Aside from breaking the thing down, as stated above... Since it's your buddy, get out to the range and shoot it first!

If all's well, $600 is a nice price. CMMG is gtg

dieselpower
05-08-2011, 9:59 AM
it was to my understanding the WASP lined barrels were actually cheaper and less desirable then the chrome lined ones, is that not the case?

thanks for the tips everyone.

I didn't know and stayed away from the whole WASP thing up til last month when a buddy asked me to look into it for his first build.

I spent over 20 days researching it. The WASP process is better than chrome lining. It may not hold up to abuse from a MACHINE GUN, used for suppressive fire in a BATTLEFIELD, but for any civilian, LEO or common grunt in the Military, it far exceeds what chrome lining does.

The barrel is just as hard, protected better from corrosion, more accurate, and the treatment is equal all over the entire surface of the barrel.

CMMG's WASP is Melonite and is nearly the same as Glocks Tenifer.
http://www.finishing.com/324/69.shtml <-- this is a good read from all posters.

You can then do what I did...start searching for information on the two processes and the salt bath process itself.

http://en.wikipedia.org/wiki/Ferritic_nitrocarburizing <--- a must read

16]
Glock Ges.m.b.H., an Austrian firearms manufacturer, utilizes the Tenifer process to protect the barrels and slides of the pistols they manufacture. The finish on a Glock pistol is the third and final hardening process. It is 0.05 mm (0.0020 in) thick and produces a 64 Rockwell C hardness rating via a 500 C (932 F) nitride bath. The final matte, non-glare finish meets or exceeds stainless steel specifications, is 85% more corrosion resistant than a hard chrome finish, and is 99.9% salt-water corrosion resistant. After the Tenifer process, a black Parkerized finish is applied and the slide is protected even if the finish were to wear off. Besides Glock several other pistol manufacturers also use ferritic nitrocarburizing for finishing parts like barrels and slides.[17]


Due to this advancement in coatings, chrome lining is a thing of the past. The only reason we still see it in the market place is due to FUD old farts who don't like change. I am sure the guys at M4C will disagree with me and say chrome lining is Gods gift, and they will have a nice salesman way to trick people into thinking it is.

fact is as it stand right now, the coating will outlast even the most determined semi-auto shooter. Your barrel will last just as long give or take a few hundred rounds. If we started seeing more manufacturers go to the melonite salt bath coatings, the process would improve due to R&D at the manufactures and within 10 years chrome lining would be completely obsolete even for machine guns.

like I said...as it stands now..with the current WASP process, its just as good as if not better in many ways than chrome lining...

dieselpower
05-08-2011, 10:37 AM
and I will also add 4140 1:9 is a better choice for a civilian / LEO than 4150CMV 1:7.

the only thing 4150CMV gains you is about 1 minute extra of full auto fire and then there is a greater chance the barrel turns into a pipe bomb waiting to explode on you when heated again....so for that extra minute you need to change your barrel or risk injury....as seen by the SF units.

Only a person needing suppressive fire would want a barrel that lasts an extra minute on full auto knowing that extra minute = a pipe bomb afterward. they take that risk..they also have access to a supply chain and regulations telling them to change the barrel. The 4150cmv will glow white hot at 2 minutes and then you are screwed after it cools... the 4140 will glow white hot after 2 minutes and just be inaccurate and a crappy barrel after it cools.

On a semi-auto you cant pull the trigger fast enough to see a difference...BUT you can pull the trigger enough to get the 4150CMV past the 1000 degree mark...altering the molecules in the barrel and possibly making a bomb... so do you really want to take that chance? please tell me where in your LEO job are you going to be dumping TEN 30rd magazines in rapid fire? You are not. And if you do...you best prepare for a boom if you don't swap the barrel.

http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA317929 <-- please read the SF unit reports. the M4A1s were exploding after only 2-3 magazines dumps. The testing didn't address the problem, just showed the shorter barrel can stand up to the same heat as a 20". the real problem was never address..why is my M4 exploding when I dump 60 rounds?

http://www.armalite.com/images/Tech%20Notes%5CTech%20Note%2048,%20Barrel%20Design ,%20Heat,%20and%20Reliability,%20030824%E2%80%A6.p df <-- Armalite understand the problem of heat altering the Mil-B-11595E 4150CMV barrels, but there is no fix for this. Its a users market. people want 4150CMV so they give them that. Armalite knows the chance a person will actually fire 500+ rounds full auto is slim, and if they do so they are doing that in an attempt to destroy the barrel, which will negate any lawsuit on manufacturer's negligence.

1:9 vs 1:7
its a moot debate, each has its pros each has its cons. 1:8 is better than both. If you normally shoot 62 and under 1:9 is best for you. If you normally shoot 69 and above 1:7 is best for you. Either will shoot the others "best" just fine. So a 1:7 can shoot 55, and a 1:9 can shoot 77...its really not bad either way.

I made this to help people out who need to see a chart to grasp this...
http://i655.photobucket.com/albums/uu272/Wiringguy/223and556twistgraphed.png

Dannicus
05-08-2011, 1:58 PM
I made this to help people out who need to see a chart to grasp this...
]

Nice chart!:D