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Posted: 11/5/2003 11:49:31 PM EDT
Hello. I just wanted some opinions on what would be the ideal barrel length for an AR15 rifle? Specifically, what length would be best for a versatile rifle with good accuracy, easy handling, and light weight? Also, if you could have any barrel length on your rifle, what length would you prefer and why? This will help me decide what barrel I will buy to put on my rifle.

Also, I know that the M4 profile barrels are popular. What I want to know is if there is any advantages to the M4 profile (I'm pretty sure most people out there don't have an M203 Grenade Launcher for their rifle)? Or is it just the fact the the M4 profile looks frickn' cool? Thanks.
Link Posted: 11/6/2003 7:08:45 AM EDT
On the Home Page of this site there is a discussion on the "Ideal Rifle" that addresses some of your questions. I have made my decision after reading the ammo oracle. I am going to buy a 20" when the funds get approved.
Link Posted: 11/6/2003 7:14:00 AM EDT
[Last Edit: 11/6/2003 7:14:21 AM EDT by Feedingcannibal]
The M4 profile is just for looks for those of us not blessed with M203 grenade launchers. However, IMHO, the M4 is the best all-around barrel for an AR. Light. Fast twist for the heavy stuff (1 in 7 twist). Chrome lined. Short (14.5"). You will be getting great hits at 100 meters. You should not be shooting greater than that in a defensive role. You will probably get many different responses. If you are interested in long-range accuracy, go with a 20 or even 24 inch. For me, for an all-pupose gun, the M4 barrel is King Shit. [image]http://community.the-underdogs.org/smiley/armed/Blasting_anim.gif[/image] .
Link Posted: 11/6/2003 10:09:06 AM EDT
[Last Edit: 11/6/2003 12:08:07 PM EDT by wyv3rn]
Seems most people choose a 14.5" or 16" barrel for their "all purpose AR's". 14.5" Advantages: -Shorter length gives it a slight edge in CQB. -Can mount a bayonet (reasonably). To a lesser extent: lighter 16" Advantages: -Flash Suppressor doesn't have to be permanently attached for us meaning easy changes between brakes, flash suppressors, FF handguard systems, etc. -Projectiles launched at higher velocity. To a lesser extent: less muzzle flash In my opinion, the 1-1.5" saved is rather insignificant and requires a well trained operator to take advantage of the tiny length savings. Good operators with M1 Garands will woop marginally trained people with 14.5" carbines in a CQB environment. The tools don't make the operator, the operator makes the tools work for him/herself. That said, I wouldn't mind having a 14.5" upper [b]in addition to[/b] my 16" M4-style. As for the M4 barrel in the civilian world, probably has something to do with looks. However, there are real advantages to it. Yes, you can mount a 37mm/40mm launcher. It will hold up against heat from rapid fire better than a pencil barrel. I could be mistaken but I believe the pencil barrel also uses a different FSB which is less common than your M4/M16 style FSBs. This might not mean much until you decide you want to replace your FSB with something else, your options may be limited. Of course you gain some weight with using an M4 profile barrel over a pencil barrel.
Link Posted: 11/6/2003 2:41:55 PM EDT
Link Posted: 11/6/2003 3:40:05 PM EDT
Troy is absolutoley right, hence the reason for the quotations around "all purpose AR's". I had assumed you meant a general purpose plinking & defense rifle which could be a wrong assumption.
Link Posted: 11/6/2003 4:04:38 PM EDT
Forget the 16" bbl as an "ideal" length. If it was not for the National Firearms Act of 1934 (as ammended) no one would make a 16" bbl. 16" is simply the minimum [i]legal[/i] length. That noted, there's nothing magical about 20" other than that was a convenient barrel length with the ArmaLite engineers scaled down Stoner's AR10 rifle to make the AR15/M16. It shot well and was a handy length, so 20" it was. Likewise 14.5" (the M4) was created merely because the original commercial contract which developed the M4 Carbine specified the M7 bayonet. Colt's was not about to reinvent anything so they used standard carbine handguards from the XM177-series and put a long enough barrel in front of the bayonet lug so the bayonet would mount. That's it, no scientific testing, etc. Pure manufacturing simplicity. I think the M4 is the most convenient barrel length and it matches very closely the length on my XM177E1 with the supressor on the end. Terminal ballistics favors longer barrels as they provide higher velocity down range. But even the 10" XM177 bbl was more than adequate at [i]normal[/i] combat ranges and newer ammunition is increasing that range. -- Chuck
Link Posted: 11/6/2003 6:02:56 PM EDT
As you can see, everyone's got an opinion. And rightfully so.. everyone is entitled to one. I love weapon systems where the hardest part is deciding exactly how you want it customized because there are too many options. [:)]
Link Posted: 11/6/2003 7:01:05 PM EDT
Originally Posted By Chuck: Forget the 16" bbl as an "ideal" length. If it was not for the National Firearms Act of 1934 (as ammended) no one would make a 16" bbl. 16" is simply the minimum [i]legal[/i] length. That noted, there's nothing magical about 20" other than that was a convenient barrel length with the ArmaLite engineers scaled down Stoner's AR10 rifle to make the AR15/M16. It shot well and was a handy length, so 20" it was. Likewise 14.5" (the M4) was created merely because the original commercial contract which developed the M4 Carbine specified the M7 bayonet. Colt's was not about to reinvent anything so they used standard carbine handguards from the XM177-series and put a long enough barrel in front of the bayonet lug so the bayonet would mount. That's it, no scientific testing, etc. Pure manufacturing simplicity. I think the M4 is the most convenient barrel length and it matches very closely the length on my XM177E1 with the supressor on the end. Terminal ballistics favors longer barrels as they provide higher velocity down range. But even the 10" XM177 bbl was more than adequate at [i]normal[/i] combat ranges and newer ammunition is increasing that range. -- Chuck
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Well the 16" is ideal for us "dissy" owners. full sight plane and just enough barrel. I personally wouldn't want anything shorter or longer. But then again, I am in a select minority lol.
Link Posted: 11/6/2003 11:01:55 PM EDT
There has been alot of good info put up there. so here is my 2 cents (hope it is worth that) I carried the 20"M16 Gov Profile A2 for 4 years in the USMC. While in college I bought a colt carbine with a 16" barrel. I thought why the heck was I carring the heavy 20" pig around (up the hill....down the hilll....). I never was in a situation that a 16" wouldn't have worked just as well, and better in many tight spaces. So I like the 16" 16" HBar - extra weight not needed (my opinion) LtWt - lightest & easiest to manuver (only good for semi auto) M4 type - best resale & most popular, alittle of the best of all worlds 14.5 M4 type w/ weld long flash hider=16" - shortest of all, one of my favorates, but limited after the longer flash hider is welded 16" fluted - very strong, almost as lite as an 16"M4, disapates alot of heat with extra surface area. 16" disapator - best accuracy for Iron Sights, similar carbine weight, add flutting if it is in your budget. Just my opinions, and i know EVERYBODYS got one.
Link Posted: 11/7/2003 1:02:36 AM EDT
Thank you all for the info. Extremely helpful. I was trying to decided if I should get an M4 profile barrel but now I think I will stick with what I have. My barrel is a 16" chrome-lined, fluted HBAR. It does not have a flash hider or muzzle brake.
Link Posted: 11/7/2003 3:41:52 AM EDT
I personally think the longer sight radius of the Dissipator is an over-rated feature with little benefit in the real world. The full length handguards are very much appreciated after firing several magazines -- hard to grab the hot barrel! But again, the 16" Dissipator is purely a function of the NFA and the non-scientific configuration of the M16 Rifle. The barrel could have been shortened almost another inch and still allowed a flash supressor to be screwed on the end (if the bayonet lug was removed). If you like 16" bbls the Dissipator is the best one in my opinion, but it needs to be put on a severe diet as it's very heavy in stock HBAR configuration. I have and recommend it. -- Chuck
Link Posted: 11/7/2003 5:08:47 AM EDT
chrome lined and fluted you have an expensive and great barrel. I would stay with it. It sounds like too nice of a barrel to remove and throw into the storage closet.
Link Posted: 11/7/2003 8:21:24 AM EDT
[Last Edit: 11/7/2003 8:26:53 AM EDT by Green0]
The M4 barrel is not a good design (really light and easy to torch) But it's light weight makes it popular too. The 18in is about optimum for velocity versus length. Go longer and the velocity gains per inch taper off drastically. The 16in is my personal favorite compromise. I have an HBAR DISSY Fluted and it is still heavy. The flutes are not deep enough, they are the same depth in both the .75in taper and the .82in taper (personally I think the flutes in the .82in region of the barrel should be deeper and then it wouldn't be heavy.) [b]IMO the sight radius increase helps me a lot.[/b] The 10.5 is about optimum for CQB work (you get some velocity with minimal length.) Go shorter and you reduce you M-16 to .22magnum balistics.
Link Posted: 11/7/2003 9:45:23 AM EDT
I like 14.5" and 20" just because thats what regular infantry units use and their lengths look just right to me. But if they would resize the handguard/gas tube system to standardize 18" for rifles, it would be great too, since you are getting the most out of it without adding too much weight. (20" still isn't bad in that regard though)
Link Posted: 11/7/2003 10:11:14 AM EDT
[Last Edit: 11/7/2003 11:10:57 AM EDT by armax]
Originally Posted By Chuck: I personally think the longer sight radius of the Dissipator is an over-rated feature with little benefit in the real world. The full length handguards are very much appreciated after firing several magazines -- hard to grab the hot barrel! But again, the 16" Dissipator is purely a function of the NFA and the non-scientific configuration of the M16 Rifle. The barrel could have been shortened almost another inch and still allowed a flash supressor to be screwed on the end (if the bayonet lug was removed). If you like 16" bbls the Dissipator is the best one in my opinion, but it needs to be put on a severe diet as it's very heavy in stock HBAR configuration. I have and recommend it. -- Chuck
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Actually I prefer the front-heavy balance of the hbar...reduces muzzle-rise and allows for a faster follow-up. Ask any of the other dissy-owners if their longer sight radius is over-rated and of little benefit. I know I can see improvements (in fact, ask your average skeet-shooter if a longer sight radius is of any benefit on quick snap shots). As for shortening it by an inch.....naw, it's perfect the way it is. Any shorter and it would be flush with the gas block. I'll take an extra length of barrel over that extra length in flash supressor any day of the week (but then again, I don't use night vision equipment).
Link Posted: 11/7/2003 1:20:10 PM EDT
I'm not buying another 5.56mm barrel without 1/7 twist or longer than 18". If I want a nine-pound, forty-inch rifle, I'll take it in a bigger caliber :)
Link Posted: 11/7/2003 2:20:32 PM EDT
Originally Posted By Green0: The M4 barrel is not a good design (really light and easy to torch) But it's light weight makes it popular too.
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I have never seen nor ever heard of a semi auto M4 carbine barrel being "torched" in a defensive role. Even in carbine classes wich will stress it the most M4s hold up fine. If you are talking military applications with full auto I MIGHT agree but for an AR15 this is a non issue.
Link Posted: 11/7/2003 3:31:02 PM EDT
Since even these old eyes can usually get all the 300 meter targets with the M4, I don't see any useful significance in the longer sight radius of the rifle or Dissipator. If it helps your shooting by all means get the sight radius that works best for you. Shooting all day long with a HBAR will make you wish you'd done all those curls. It's almost heartbreaking, but actually kinda fun to see the [i]non-believers[/i] at the first morning break on a weekend long shooting course where they'll put 600-800 rounds down range from the "low ready." They're asking guys if they have a spare lightweight barrelled upper in the car. One poor guy I watched had a 20" HBAR. National Match? Yeah I want a 13+ pound AR15 for this. The rest of the time I'll keep it light. -- Chuck
Link Posted: 11/7/2003 3:46:15 PM EDT
like this one Green0? [img]http://photos.ar15.com/WS_Content/ImageGallery/Attachments/DownloadAttach.asp?sAccountUnq=12467&iGalleryUnq=934&iImageUnq=19561[/img]
Link Posted: 11/7/2003 3:57:24 PM EDT
The firepower branch at Quantico determined that a length of 14" was the minmum for reliability with a standard gas port. The extra .5 of an inch was because of the need for the bayonet.
Link Posted: 11/7/2003 11:49:18 PM EDT
I hear that a lot but have never seen it documented. Got a link?
Link Posted: 11/8/2003 4:04:10 AM EDT
I am not sure where I read that at, I think it was from someone who worked either for MCATEA or the old fire power branch.
Link Posted: 11/8/2003 8:07:35 AM EDT
Personally, and this is just my opinion, the ultimate all around AR barrel would be an 18" A2 (light under HG) profile. Full length handguards, full length sight radius, rifle gas system, and reasonably light weight.
Link Posted: 11/8/2003 9:33:38 AM EDT
Originally Posted By STLRN: I am not sure where I read that at, I think it was from someone who worked either for MCATEA or the old fire power branch.
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That's one of those things I've been trying to document. It's up there with why Colt went to the large pivot pins originally. If you come across anything please do post.
Link Posted: 11/8/2003 10:02:32 AM EDT
Originally Posted By bsbg: Personally, and this is just my opinion, the ultimate all around AR barrel would be an 18" A2 (light under HG) profile. Full length handguards, full length sight radius, rifle gas system, and reasonably light weight.
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Im finding myself agreeing more and more everyday [):)]
Link Posted: 11/8/2003 10:04:55 AM EDT
I like my 16" HBAR, but thats just me It is a bit heavy, but Ill never be an operator, so I really dont care. Of course, in the end its up to you, so get what you want.
Link Posted: 11/8/2003 10:41:48 AM EDT
That M4 looks like it was hit by a LAW! what the hell happen there? In the Corps I carried 20" w/ 3 round burst and M4 w/ full auto. Man-o-man I have never seen that before?
Link Posted: 11/9/2003 4:32:38 PM EDT
I like the 14.5" barrel most, in something lighter than an HBAR. It's reliable, light, it points well, the ballistics are good enough within reasonable ranges, and with a permenantly attached flash suppressor, you don't need a tax stamp for it. But that's just my opinion.
Link Posted: 11/9/2003 5:24:36 PM EDT
I have a 20' A-1 configuration, a couple of 16' carbines, an RRA M-4, and 1 11.5/5.5 A-2 upper. I love my 11.5/5.5, very reliable but alittle loud & lots of muzzle flash(with SA surplus.) Hessian-1
Link Posted: 11/9/2003 8:38:53 PM EDT
Originally Posted By Hessian-1: I have a 20' A-1 configuration, a couple of 16'
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a 20 foot A-1 and a couple of 16 footers? Jeez, that must be a bitch to hump. [;)]
Link Posted: 11/9/2003 9:54:42 PM EDT
[Last Edit: 11/9/2003 9:55:35 PM EDT by spacemenow1]
Well. This is my rifle. It has the following: Bushmaster Upper and Lower Receivers Jewel Trigger Ace Skeleton Stock 16" HBAR Chrome-lined Fluted Barrel ARMS SIR 45C ARMS #40 BUIS PRI Front Flip Sight SOG Armory VFG Surefire M962SU Aimpoint Comp ML2 and ARMS Mount Hogue Grip Fulton Armory Extended Bolt Release Harris Bipod with ARMS Mount [img]http://bigbikeriders.com/photopost/data/500/492DSC00050.jpg[/img] [img]http://bigbikeriders.com/photopost/data/500/492DSC00053.jpg[/img] [img]http://bigbikeriders.com/photopost/data/500/492DSC00048.jpg[/img] Some of you may question the choice of the Jewel trigger but I have found that this trigger is extremely reliable and robust. Also, since you can set trigger pull to be very light, it lessens trigger finger fatigue and helps with accuracy. Anyways, you guys have convinced me to keep my 16" barrel, but I have a new question. Should I put a flash suppressor on my rifle? Would it be legal to thread the barrel to install a Phantom or would it have to be pinned? Thanks for all of your execellent insights, advice, and opinions.
Link Posted: 11/10/2003 5:13:00 AM EDT
This has been an interesting discussion; thanks for all the insights guys. For my two cents: First, what do we mean by "general purpose?" I will assume the most important would be CQB (house clearing), followed by 5" fast snap shots at 50yds, and a single precision shot into 10" at 600m from an improved rest. (Comments on this definition?) Choices seem to be 14", 16", or 18" all w/ flash hider, varying from A1 to 0.75 with flutes. Chrome vs. SS Match. Fact is, this is all a matter of compromise and skill. A great shot with a 14" SS Match HBAR (and the right scope/ammo) from prone will do better than most of us with anything at 600yds from a rest. And lots of experts have done just fine with 20" for CQB; a shorter barrel may be a bit better, but skill beats equipment. I decided on a 16" (w/ flash) SS match 0.75 fluted as this was short enough not to bump into too much, avoided the NFA grief, and was still accurate enough that when I missed I would have to blame my lack of skill, not the equipment.
Link Posted: 11/10/2003 12:16:44 PM EDT
Well, my 16" HBAR seems just fine. But, I guess I'm just use to humpin my 30.06 in the forest all day long. Joe
Link Posted: 11/10/2003 2:11:22 PM EDT
Seems like alot of people like the M4 profile for most things they do with an AR. So to all you M4 owners, who has the best price on a chrome-lined M4 upper?
Link Posted: 11/10/2003 3:09:36 PM EDT
spacemenow1 - Can you tell me who made your 16" chromed lined flutted HBAR (I believe you said earlier it a 1/9 twist?) Thanks
Link Posted: 11/10/2003 3:28:30 PM EDT
It is a Bushmaster barrel.
Link Posted: 11/12/2003 4:28:58 AM EDT
Originally Posted By ak007: Seems like alot of people like the M4 profile for most things they do with an AR. So to all you M4 owners, who has the best price on a chrome-lined M4 upper?
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[url=http://www.cmmginc.com/inventory_a/uppers_tbl.html]CMMG Inc.[/url] had DPMS make true M4 barrels for them - 1 in 7 twist, chrome lined, 4150 steel, 14.5". [image]http://www.cmmginc.com/cmmg_images/tbl_images/uppers_images/M4A3_Perm_A2.JPG[/image]
Link Posted: 11/12/2003 12:59:16 PM EDT
CMMG looks good. Do you own one? But for that upper price you could get a whole M4 kit from J&T with chrome upgrade. Dont know about the twist rate on it. So is the 1/7 twist on the M4 so it can shoot heaver bullets with accuracy to make up for the fps lost with the 14.5" barrel?
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