checking out a used CMMG AR15 tommorow, what should I look for?

[Z.1]

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]

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

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]

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...f&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%...4%E2%80%A6.pdf <-- 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...

[Dannicus]

I made this to help people out who need to see a chart to grasp this...
]

Nice chart!