question about fluted bull barrel

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themachine

themachine

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Let me start off by saying I just about to get my first AR so yes, ignorance is inevitable right now. I'm about to get an MP15 w/ four sided rail. My question is this: I want to replace the standard barrel with a 16" fluted bull barrel. I'm really trying to go for the "best of both worlds". 16" because it's easier to transport (and for CQB) but bull barrel for "extra range" and I've heard they can handle more rounds at rapid fire.

What do ya'll think?

I know there's more than enough to be said for both sides but I'm considering a little bit of everything. How does the bull barrel handle multiple rounds at rapid fire? What about accuracy out to 500-600M?

Let it rip and I'll do my best to digest it all.
 
I'm missing something - how does a "bull barrel" translate to extra range? A bull barrel trades rigidity for weight - neither gives you more range. Fluting will help with heat dissipation and reduce the weight - perhaps significantly, depending upon how deep the fluting is. Of course, at some point, if you flute it enough you sort of wonder why you bothered w a bull.

A longer barrel yields (slightly) higher velocity = longer range. There's a thread alive on here right now that discusses barrel length - essentially I think a reasonable summary is that out to around 400, the 16" doesn't give up enough to matter vs a 20".

Accuracy is mostly a matter of sight radius - if you're using irons, longer is better - the trade-off of length vs manueverability is a personal decision.
/Bryan
 
thanks that does clear up some things for me. I'm probably listening to the wrong people on that.

What about amount of firing being done. Is the thicker barrel better to go with if your going to be putting more rounds through it in one sitting?
 
A heavy fluted barrel is going to cost more than a skinny barrel of the same overall weight. What you'll gain is heat dissipation, which means if you fire 20+ shots, the rounds won't "wander" as much as they would with a skinny.

You won't get any extra velocity, that's for sure...well...wait. Some barrels do spit bullets faster than others. But this characteristic isn't necessarily tied to "quality" or accuracy.

I don't know much about this subject in rifles. But I do know about this in revolvers. A Ruger GP100 is a decent gun but not known for match accuracy. A well-tuned vintage S&W is likely going to be more accurate in the same caliber. But, the Ruger will often spit bullets faster than that same more-accurate S&W. The difference can be pretty wild - Buffalo Bore's tests show up to a 100fps difference in 357Magnum in the 4" to 6" barrel range.

It's possible that a fluted heavy barrel is "better quality" than a standard rifle skinny, and that might affect bullet speed, accuracy or both. Or neither. The most likely gain on a heavy fluted is aim stability across high round counts.
 
Nice.

My main deal is just wanting to make the AR I'm getting as versatile / multifunctional as possible. I'm not going to be buying several different rifles for each different application (although I'd like to).

The extra weight doesn't worry me (just going with a 16"), I'm more looking for something that can handle multiple rounds and keep fairly tight groups. Although I won't be doing that too much I just want to know that I have that option if I want to do some plinking.

I'll also be doing some hog, coyote, and varmit hunting so it's pretty much gonna be a multipurpose rifle.
 
I'm not going to be buying several different rifles for each different application (although I'd like to).
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Dude it's an AR! Start collecting uppers! :evil: You can have your bull barrel match chamber varmint upper, your 16" M4gery upper, your 10.5" CQB upper (with tax stamp), etc.
You might want to research twist rates. Most are 1 in 9" because it's a good all around twist but if you want to shoot heavier stuff (over 70gr) a 1 in 7 might work better. I'm not sure if the faster twist rates hurt lighter thin jacketed (varmint) bullets <52gr but it's something to consider.
 
Thanks for the info (my ignorance is quickly dissappearing).

I'll have to make sure I treat the wife with extra spending money for clothes so she doesn't say anything about all the "toys" I'm getting!

Good ideas to think about, thanks for your help.
 
Fluting will help with heat dissipation
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Well... a fluted barrel is going to get hotter faster than a non-fluted bull barrel with the same outside diameter. The advantage of a fluted barrel isn't heat dissipation at all. I think a plain bull barrel is going to be the more tolerant of the two when it comes to heat. The advantage of a fluted barrel is weight reduction while maintaining rigidity, and honestly, you don't shave that much weight by going to a fluted barrel. So really the bull barrel is the winner for a rigid aftermarket barrel IMO, although the look of the fluted barrels is attractive.

Jason
 
It has been a long time since by thermo dynamics classes in college (20 yrs). I don't use them in my work, so my clarity is spotty.

But, while I agree the fluted barrel will heat faster since there is less mass to raise in temperature, it will also dissipate heat faster due to the higher surface area afforded by fluting a barrel of the same diameter. This assumes the ambiant air temperature is lower than the barrel temperature, but that should be a fair assumption.

The questions relevant are which reaches the lower temperature in consistent shooting. All other things being equal, I would think the fluted barrel will stabilize at a lower temp, but alot of this will probably depend on your shooting pattern.
 
Bull barrel = heavier and more rigid than a standard barrel which means the extra mass helps with heat, though it will still get hot just not quite as fast.

Also barrel whip/flexing is less pronounced thereby slightly increasing precision.

Downsides - It's heavier and some people can't handle a hike with an extra couple of pounds riding on their shoulder.


pre·ci·sion (pr-szhn)
a. The ability of a measurement to be consistently reproduced.
 
Sounds like you want two different uppers: a standard 16'' and a heavy 20-24''.

That way, you'll have two uppers that fill their respective roles very well, as opposed to one upper that's only so-so at any one thing. Later, you could buy another lower and tailor it to whichever upper you choose to keep on it.
 
But, while I agree the fluted barrel will heat faster since there is less mass to raise in temperature, it will also dissipate heat faster due to the higher surface area afforded by fluting a barrel of the same diameter. This assumes the ambiant air temperature is lower than the barrel temperature, but that should be a fair assumption.

The questions relevant are which reaches the lower temperature in consistent shooting. All other things being equal, I would think the fluted barrel will stabilize at a lower temp, but alot of this will probably depend on your shooting pattern.
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I guess it would depend on if you want to wait around between shots for the barrel to cool. If you were to shoot 10 rounds rapid fire through a fluted barrel, I would venture that it's going to get much hotter than that bull barrel will. If you are going to wait intermittently for the barrel to cool down, you'd have to do it more often with the fluted barrel, albeit it would be a shorter wait, as I'm sure it would cool faster. If you are going to be shooting slow fire, in small strings at a time, as most folks that are in the market for these barrels do, then it's a moot point because it's not going to get that hot anyway.

Jason
 
A heavy fluted barrel is going to cost more than a skinny barrel of the same overall weight.
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\

Not always true.

The machining for a lighter profile barrel often leads to higher costs than on a bull barrel.
 
Best advice is to just take that MP 15 and shoot it. I think you will be very happy with it, it is a damn fine rifle. After you shoot and learn to run it and figure out what you are wanting to do with it, then you can pick up just about any kind of upper you want. I would be hitting the range with it, a lot of ar shooters at the range. Make some new friends and ask questions. Most are a pretty friendly bunch and will let you try out their iron.
 
Yeah, I'm probably kidding myself by thinking I'm going to stop at just one set-up. You can never have enough toys when it comes to guns!;)


I think I'll start with 16" bull barrel and go from there.
 
Why would you want to buy an M&P and switch the barrels? There are plenty of companies who have been in business making ARs for decades longer than S&W, who will make you the rifle you want up front. And here is everything you need to know about fluting and bull barrels.... http://www.varmintal.com/aflut.htm

I shoot steel plates are 500 with my 16", so it can be done. But rapid fire, you're still going to have wander.
 
I'd skip the 16" bull barrel. It will be terribly front heavy and not handy at all. If you will be rapid firing a lot, you probably won't have time to carefully aim each shot.

If you want an accurate AR, you have three primary options a DCM gun, an SPR clone (Special Purpose rifle), or a varmint gun.

DCM guns are 20" match HBARs which look pretty much like a standard M16 but have heavy, free floated barrel with normal looking handguards. They usually have carry handles but I've heard of a few flattops with carry handles.

Varmint guns are typically 20"+ bull barrels with flat tops, free floated barrels, bipods, and scopes.

SPRs have free-floated 18" stainless match HBARs with Knights RAS handguards (depends on specific model).

None use standard mil-spec triggers and all have some type of free-floated barrel. Consider what SWAT and Army use to clear houses... it isn't 16" bull barrels. Most folks don't rapid-fire or do mag dumps at 200, 300, or 600 yards.

Do you want a bench gun, a fighting carbine, or something in between? If it's a bench gun, get a DCM or varmint gun. If you want a fighting carbine, get a M4 clone. If you want in between, build or buy an SPR clone. Bring $$$. Match barrels and high-end rails are not cheap.

Don't forget to budget for the scope and for ammo. Any match barrel needs to be fed quality, match-grade ammo for good results. Wolf 55gr FMJ won't cut it. Can you afford $0.50-$1.00 per round?

If I were you, I'd get a Stag 2T or M&P 15T. Learn how to shoot with irons and get your skills down with groups at least 2" at 100 yards. Once you're at that point, then look to upgrade.

And don't forget quality ammo (that can't be stressed enough).
 
I think I'm just gonna stick to the MP15 to start with. From everything I hear and everyone I talk to, these things are supposed to be incredible.

I guess one of the main reasons for considering the bull barrel is I want to be able to spend some good time at the range firing it and I want the accuracy to stay pretty tight even if I'm doing a lot of shooting.

If weight is the only downside to the bull barrel I still may consider getting the 16" down the road.

Again, I'm sure that over time I'll have more than one AR (or multiple uppers) but until then...

What do y'all think? Does that make any sense?
 
In the FWIW department: Some years back I bought a good-used Bushmaster Match Target. Went to the benchrest to check the sight-in. (Tasco World-Class 6x24x40).

It took maybe four or five three-shot groups for me to get it settled on 1" high at 100 yards. All groups were half-MOA. As near as I could tell, had it all been one 12- or 15-shot string, the group would have been no more than one MOA. I was impressed...

It was a 20" barrel, IIRC, what I think of as medium, no flutes.

The stock trigger was terrible, but Mr. Jewell does good things, I'm told. :D
 
Buying a S&W M&P15 and changing the barrel is like buying a $1000 bolt gun and having the barrel changed. One of the major costs on guns is the barrel and you are not going to use the one you paid for. If you know you are going to change it, why don't you find an upper that already has the configuration you want? You could also assemble the whole upper yourself, but you don't sound like that type of person if you're planning on buying a M&P in the first place.

Also, I feel obligated to point out that flutes do not make a rifle more versatile. Sure, they reportedly help cooling; funny thing is no one has found a good way to prove that they really do make a big difference. The main reason for flutes is to reduce weight and to look cool.

From everything I hear and everyone I talk to, these things are supposed to be incredible.
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Understand that the information is only as reliable as the source. Not to say that the people that you talk to are dunces, more that someone that has only shot the M&P or someone that hasn't shot a kit built rifle wouldn't know what they were missing/paying for. The M&P's are claimed to be fitted at the factory. Is fitting required to make an AR reliable and how much fitting do they do above and beyond other companies? I have no idea, but I suspect the fickle gun consumer would assume the M&P to be the AR of the future based on the name on the side. I may be wrong (wouldn't be the first time) but I didn't see all the bells and whistles, nor feel the hair raise on my neck when I held one. The review I read was weak sauce at best; "This amazing rifle comes with a SINGLE STAGE 7LB TRIGGER!!! ROLFCOPTER!! It comes with the A2 fully adjustable iron sights, but also has a rail underneath that you can attach ANYTHING TO!! FRICKIN ANYTHING!!! YOU CAN PUT ANY SCOPE ON THIS RIFLE!! It is so amazing." (http://http://www.shootingtimes.com/longgun_reviews/swmp15_121906/index.html)

Maybe I'm a nay sayer because I can't see what makes it better/more expensive/worth while. At the same time, I get this vibe that they get a premium price because it is a S&W.



Edit: read this http://www.m4carbine.net/showthread.php?t=6642
 
I should have known better to have openly displayed my ignorance to a bunch of veterans on AR's. Yeah, I know I'm a rookie!

In all seriousness, I'm planning on getting the AR this coming weekend and I guess now is the time to have an open mind on the subject. What do you guys think is a solid AR to get. I'm budgeting $1000 - $1200 for the rifle not including the accessories (Eotech, flashlight, etc...).

I don't want to get a "cheap starter" when I've already saved the money to buy a nice one. The gun show is this weekend and I've found some great prices on AR's.

I've liked the MP15 because it feel's very solid and I've been able to shoot a few that my friends own. Not to mention the ones I've looked at already come with the 4 sided rail.

My friends have anywhere from Colt, Rock River, Bushmaster, and S&W. I know that those are reputable makes but what do you all think?
 
What's with this "rail" bit, and you're also talking about accuracy? For a precision shot, if you rest that sucker on a knapsack, sandbag, whatever, you're gonna have rounds going everywhere.

GET A GOOD LOWER. Put one of Arnold Jewell's triggers in it.

Then, start collecting uppers. Get a 16" with all the tacticool stuff - AND a good 20-24" match grade upper at the same time. I'm guessing you can probably do that inside that $1200...

Also keep in mind that MOST AR "manufacturers" don't know what a real match grade barrel is... When they tell you you can use the same bolt in both your spray & pray and the target upper, that's a sign that they're clueless.

I'd probably start with a Bushy or RR lower (Colt, etc., you pay for the name, don't really get any extra quality). Standard buttstock, maybe with a buffer and a gap tightener... Stuff in one of Arnold's triggers, and you're good.

LEARN HOW THE THINGS ARE MADE. Buy your lower as a parts kit.
 
I'm not sure that a fluted barrel, that is subsequently shrouded inside handguards will offer much improved heat dissipation at all.
 
Yeah, I know I'm a rookie!
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We were all rookies at one point. 4 months ago I didn't know anything about the AR platform. I am probably biased because I always look for a deal. When I got into building ARs (impending election doom) I found that for $600 I can build what other companies are selling for upwards of $1k. The extra cost comes from 11% federal excise tax, research and development, warranty, advertising, etc. which makes sense I suppose. My biggest deal is that I don't buy anything I can't sell for at least equal money. If you don't want to spend the time reading the how-to page on arfcom and don't want to shop around for the best deal on a good kit or wait for shipping, buy a complete rifle from a dealer. Building your own is very rewarding and forces you to become familiar with your rifle and how to detail strip it.

For $1200 you can get a M&P and I'm willing to bet you'd be very happy. At the same time, for $1200 you could get a stripped lower and a kit, a free float 4 rail handguard, flip up irons, a JP trigger (highly recommended), and 10 mags from the cmmg bargain bin for $1200 or thereabouts. Get the JP spring kit instead of the whole kit and save $140 for a grip and a buttstock and still be at $1200. Conversely you could get two uppers and a lower for $1200 and buy upgrades as the bank account allows.

I'd probably start with a Bushy or RR lower
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I don't know what the difference is between lowers. As long as they are milspec and hard anodized, only the name on the side is different, right? FWIW I use DPMS.
 
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