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Thread: Barrel profile preferences

  1. #11
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    The most I can find is that, that is a misconception mixed up with the M4 style barrel having a notch to fit the M203.

    Here's an interesting thread:
    https://www.m4carbine.net/showthread.php?t=67942&page=2

    I hope an expert can hop in. I'm interested in learning too!
    Muzzle punch optional.

  2. #12
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    Quote Originally Posted by Eric D. View Post
    I like the midlength government profile. It doesn't make sense from an engineering standpoint but the fact is I just don't like the look of lightweight barrels. I also believe there is merit behind a 0.750" diameter under the fsb. For the most part, the taper pin holes are arbitrarily located. My BCM middy has a full 360 degrees of hole through the barrel where it was drilled for taper pins. I've been told that the pins are not to pass into the barrel more than half of their diameter. Having put almost 1500 rounds through that upper, I'm pretty sure its just fine. The point is that when going to 0.625 diameter, there is a lot less wiggle room for where the holes are drilled.
    Hopefully we can skip things like appearance and assembly concerns. If you don't trust the person assembling your upper or attaching your gas block, you have much bigger problems than barrel profile.


    Quote Originally Posted by WS6 View Post
    Noveske's N4 barrel profile is the best one in my opinion. Same as USGI weight, but the rigidity is where you want it: closer to you, closer to where the barrel would likely be flexing, etc.
    I agree re: the N4 provided one has chosen to accept the weight of the M4 barrel. The N4 profile is the most sensible. It is ~5oz. heavier than the Colt 0.625" dia. barrel, which isn't a lot but in conjunction with other weight saving measures, that likewise do not sacrifice function, it can be part of a greater savings.



    Quote Originally Posted by crusader377 View Post
    I prefer the lightweight profile barrel. This is due to the weight savings and more importantly, I believe that the LW profile balances much better than a M4 or Govt profile carbine.

    To answer your other question on muzzle climb, I have noticed no difference between my LW profile carbine vs my M4 profile carbine.
    I prefer the A1 profile as well, but, again assuming other weight-saving choices, muzzle climb and felt recoil *can* become an issue. While it was never intended to be run hard/alot, this gun kicks and climb considerably more than a standard AR carbine.
    (yes, I understand that it is both shorter and lighter, but the point re: going lighter remains the same)

  3. #13
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    I’m no expert but my understanding that the A2 barrel profile was incorporated to reduce bent barrels. Every A1 barrel that I saw was bent in front of the FSB. We supported airborne units and for some reason they liked to jump out of aircraft with their weapons. I think the idea was that making it thicker at that location would cut down on the number of bent barrels. When the M4 was developed I would guess that the same thought continued and so the barrel was made thicker in front. The M203 cut was made because the 203 was designed to be mounted on a thinner barrel.

    I have one AR with a DD lightweight barrel and don’t notice any difference in recoil or muzzle flip, my wife on the other hand does but not so much that it makes a real difference. Remember, the M16 and M16A1 used what we now call a lightweight barrel as standard.
    Certified Glock Armorer

  4. #14
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    Quote Originally Posted by MistWolf View Post
    .75 at the FSB makes sense. It doesn't make sense ahead of the FSB when the barrel aft is a smaller diameter. I could go for a light weight barrel that's .75 at the FSB
    I have such a thing. I thought it was weird when I got it and I'm interested to see your suggestion of it. Want to guess who made it? Guessing in 1...2....3.... Del-Ton, Inc. I got it as a plinker, with an A2 upper, so no one needs to remind me how it doesn't compare to the DD and BCM products I own. Anyway, I ordered it as their 16" lightweight midlength, expecting a typical .625" gas block pencil barrel, and was a little amused when I opened the box and saw that .75" diameter gas block seat. It appears that they simply took a government profile blank and machined the portion forward of the gas seat down to about 0.6-0.625" or so. (By the way, .625" barrels are only that at the gas block seat and are closer to 0.590-0.6" forward of that, while my government profile 16" midlength barrels are not quite as skinny under the handguards as my BCM lightweight 16" midlength.) On the one hand it seems like a cheap approach, on the other hand it seems to have the benefit regarding taper pin holes that was mentioned.

  5. #15
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    Early BCM lightweights had 0.750" gas seats because of issues sourcing proper FSBs that were 0.625". I would guess Delton made the same decision for the same reason.

  6. #16
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    Quote Originally Posted by rob_s View Post



    I agree re: the N4 provided one has chosen to accept the weight of the M4 barrel. The N4 profile is the most sensible. It is ~5oz. heavier than the Colt 0.625" dia. barrel, which isn't a lot but in conjunction with other weight saving measures, that likewise do not sacrifice function, it can be part of a greater savings.



    The (how the hell do you make that "approximate" sign?)5oz is well-hidden because the majority of the extra weight is closest the receiver, which is exactly the opposite the M4.

  7. #17
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    Shift + tilde, upper left of keyboard for me
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    Quote Originally Posted by WS6 View Post
    The (how the hell do you make that "approximate" sign?)5oz is well-hidden because the majority of the extra weight is closest the receiver, which is exactly the opposite the M4.
    B.A.S. Mechanical Engineering Technology

  8. #18
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    Quote Originally Posted by Eric D. View Post
    Shift + tilde, upper left of keyboard for me
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  9. #19
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    it's next to your '1' key, above your 'Tab' key.

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