Barrel profile preferences

[PalmettoPrecision]

New to the forum, been lurking for years. Never made an account, because I could usually find answers to my questions through searching, until now.

Bringing up the long debated barrel profile choice, particularly the gov't vs. lightweight. Never handled an AR with a pencil barrel, but have read everywhere that 5+ oz. off the front of the gun gives it better balance, control, etc, and I'm sure it is more comfortable to carry around for any extended amount of time. But here are the questions:

Does anyone experience any noticeable difference in muzzle climb? Does the lightweight have much more?

Anyone on here actually bend/damage a pencil barrel? heard of rare occurrences where an extremely heated barrel has bent being dropped or hit somehow.

Any other advantages/disadvantages are welcome.

I'm not much of a talker, would just rather read and learn, so thanks for the help.

[brit]

I actually prefer LW profile over govt. profile as I just don't see the point of having a barrel at .75" thickness after the FSB and .625 before it.

However, I think the best profile is from noveske, offered on their CL barrels. It has a slow taper starting at the base running the length of barrel excluding the FSB. I'm not sure why more companies don't follow that lead. I pretty sure it runs from .72 to .70 behind the fsb and .68 in front. There is a picture in post #2 of this thread: https://www.m4carbine.net/showthread.php?t=61263

using A2 flash hiders, I haven't noticed any difference in muzzle climb based on the weight/thickness of a barrel.

[BAC]

The government profile barrel removed weight off the wrong end of the barrel. They remove mass from the middle of the barrel but leave the ends thicker. This successfully reduces weight, but that's it. The barrel is more likely to flex, will whip more, and is more stressed than barrels of uniform diameter or with taped profiles.

From an engineering standpoint, there's nothing intelligent about the government barrel profile. From a practical use standpoint... there's nothing intelligent about the government barrel profile.


-B

[Eric D.]

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.

[WS6]

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.

[crusader377]

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.

[WS6]

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.

I had a Sabre Defense A2.
When I passed a bore-brush through the bore, over where the taper pins were, I could feel it slow down/drag. Same with a tight patch. I looked down the bore and the gas-port was not burred or anything, nor were the patches torn/snagged.

My only conclusion was that the taper pins had deformed the bore slightly. I have read that this is not uncommon.

My Noveske does not suffer this.

[MistWolf]

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.

.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

[Casull]

I like standard barrels that are medium profile back to front. I also like LW barrels, especially Centurion Arms' LW profile.

I like my government profile just fine, the weight is all up front making a good "barrel weight" ideal but... it is what it is in the end.

I think if we consider that the Gov't profile wasn't particularly for free-float it makes sense the barrel was shaved under the hand guard, and there are other points "supporting" the barrel in some way.

It's a worthy presumption to suppose that perhaps it was thought to improve upon heat reduction around where the operator's hand would be.

[pira114]

From what I understand, the Gov't profile exists simply for the M203 to fit without a significant weight penalty.

Someone correct me if I'm wrong please.

[Casull]

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!

[rob_s]

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.



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.




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 (https://sites.google.com/site/tacticalyellowvisor/projects---guns/10-3-ultralight-sbr) 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)

[5pins]

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.

[SomeOtherGuy]

.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.

[rob_s]

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.

[WS6]

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.

[Eric D.]

Shift + tilde, upper left of keyboard for me :D
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~




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.

[WS6]

Shift + tilde, upper left of keyboard for me :D
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Tilde? I fail at symbols :(

[militarymoron]

it's next to your '1' key, above your 'Tab' key.