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16" Carbine Barrel vs. 16" M4 Carbine Barrel

Discussion in 'GATE AR-15 Forum' started by MSGC89, Mar 19, 2010.

  1. MSGC89


    Mar 9, 2010
    MS Gulf Coast
    I'm looking at purchasing an AR-15 with a 20" heavy barrel from a family friend ($500 like new) and I want to get a 16" barrel for ease of use and storage in a patrol car. My question is: what is the difference between the 16" carbine barrel and the 16" M4 carbine barrel? If both are 1:9 and chrome lined, does the exterior contour really make a difference?

    Thanks for the help.
  2. Constructor

    Constructor Moderator

    Dec 10, 2009
    Very little IMO unless of course you need to mount a grenade launcher or depends on how light you want the rifle.
    There are so many different contours it's difficult to know what you will get, A carbine "HBAR" is pretty heavy apx .850 under the guard and .730 from the GB to the muzzle. A carbine "gov." is thin under the guard and thicker apx .730 from the GB to the muzzle like a M4 without the grenade cutout which is backwards from how a barrel should be contoured. It should be larger in the rear and narrower out front like a bolt rifle barrel to retain rigidity and aid accuracy. The carbine "lightweight" is thin the whole length and the carbine M4 is thin under the guard and heavy out front with a grenade launcher cutout.
    One thing to consider is some companies still use rifle type feed ramps on the barrel extension and some use M4 feed ramps, we used plain rifle ramps for years with no problems but, if the receiver you have has M4 ramps then the barrel also needs to have M4 ramps. If the barrel has the longer M4 ramps then you can always cut or grind to match the ramps of the receiver to the barrel extension.
    Last edited: Mar 19, 2010

  3. MSGC89


    Mar 9, 2010
    MS Gulf Coast
    This was very informative. Thank you very much.:wavey:
  4. RainierArms


    Oct 23, 2004
    There are so many companies that label things these days, the best thing to do is look at the specs. As Harrison has pointed out, look for:

    Chrome Moly or Chrome Lined?
    Twist Rate (which you know)?
    What type of Steel (4140, 4150, CMV)?

    Usually, if you know who the MFG is, we can give you a good assessment on the quality of the barrel. These days, there are so many different barrel MFGs, you really need to know what you are buying.