18 inch AR-15???


July 12, 2005, 10:13 PM
Does any company(ies) make an 18" barrel AR-15. I only see 16 or 20 inch platforms available. I think the 20" is ideal for maximizing ballistic potential of the 5.56 and it cuts down on the flash/noise, but is a bit longer than I would like esp. with an attached flash suppressor. The 16" seems to go too far in the other direction with obvious drawbacks. I have an 18 inch mini-14 that performs well enough but would like to venture into the AR world. At this point I was thinking of an 18" with flash supp. a short telescopic stock and a detachable carrying handle. Does such a monster exist?

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Jim Watson
July 12, 2005, 10:27 PM
JP uses 18 inch barrels, about the shortest that will handle a rifle gas tube. You could probably order up what you want on an a la carte basis if they don't have a specific model.

I had a barrel cut to 18.5" and turned down to A2 profile. Very handy.

July 12, 2005, 10:45 PM
Yes, there are plenty of 18" AR15 barrels. For example, this is the standard barrel length for the SPR.
Let me offer you a piece of advice: don't buy an AR15 from one of the major manufacturers. For the same kind of money, you can get a rifle made to your specifications out of the best component parts made. For example: If you want an 18" barrel with a 5.56 chamber, chrome lined with a mid length gas set up in a superlight profile: you can get exactly what you want. With Colt, Bushmaster, DPMS, Rock River etc. you will settle for what they offer with only slight variations. Don't settle for anything. Get the best. Get exactly what you want.
Go to AR15.com and check out who the major players are. Two good ones are MSTN and Denny's Guns. You will see several others. They are in the Industry section of the board, they are on the equipment exchange section of the board as well as in the regular AR15 forum.

Harry Tuttle
July 13, 2005, 12:48 AM

July 13, 2005, 04:05 AM
You can also just take a 20" and have it cut/threaded to 18". I did, only cost about $50 for the job, and it is a wonderful length and compromise between full length and carbine.

Zak Smith
July 13, 2005, 12:15 PM
I'm a fan of rifle-length gas 17 and 18" uppers:
http://apollo.demigod.org/~zak/DigiCam/6.8SPC/small/138_3830_img.jpg (http://apollo.demigod.org/~zak/DigiCam/6.8SPC/?medium=138_3830_img.jpg)[ link to LARGER image ] (http://apollo.demigod.org/~zak/DigiCam/6.8SPC/?medium=138_3830_img.jpg)
http://apollo.demigod.org/~zak/DigiCam/MSTN-LW17/small/157_5712_img.jpg (http://apollo.demigod.org/~zak/DigiCam/MSTN-LW17/?medium=157_5712_img.jpg)[ link to LARGER image ] (http://apollo.demigod.org/~zak/DigiCam/MSTN-LW17/?medium=157_5712_img.jpg)

July 13, 2005, 12:34 PM
Zak, this is off-topic, but what color is the paint on the second gun?


Zak Smith
July 13, 2005, 12:39 PM
It's K-G Dark Earth and Aluma-Hyde II Coyote.

I had an old batch of AHII "Desert Tan" which was actually darker than the Coyote and used on this lower, but none of the new cans of DT have been the same color (all much lighter).


July 13, 2005, 04:54 PM
Cool! I ask because I'm trying to get a feel for what this new Flat Dark Earth color might look like. Thanks.


Zak Smith
July 13, 2005, 05:00 PM
The BUIS on that gun are Norrells "Tan Flat - Toupe"

Zak Smith
July 13, 2005, 05:03 PM
Here's a picture of the new Magpul M93B stock, which is a little different color than the old ones:
http://apollo.demigod.org/~zak/DigiCam/MSTN-LW17/small/167_6718_img.jpg (http://apollo.demigod.org/~zak/DigiCam/MSTN-LW17/?medium=167_6718_img.jpg)[ link to LARGER image ] (http://apollo.demigod.org/~zak/DigiCam/MSTN-LW17/?medium=167_6718_img.jpg)

July 13, 2005, 10:09 PM
Zak, is the 17 and 18" barrel with full length gas tube the same type of deal as Bushmaster's 16" Dissipator?

I'm kicking around my first AR purchase, and that setup (somewhat shorter barrel, but with full length gas tube and sight radius) seems like BOB W. Any downsides to it - parts interchangeability or anything.

July 13, 2005, 10:40 PM
"The 16" seems to go too far in the other direction with obvious drawbacks."


Zak Smith
July 13, 2005, 10:47 PM
Zak, is the 17 and 18" barrel with full length gas tube the same type of deal as Bushmaster's 16" Dissipator?
The Bushmaster 16" Dissipator has a hidden carbine length gas block under rifle length handguards, and then a front sight tower (not used as gas block) in the normal rifle position.

July 13, 2005, 11:49 PM
Thanks for the advice, it looks like I might have to stray away from the big manufacturers for what I want.

As far as the 16 vs 20 stuff, I have no vendetta against the 16 but to me it sounds significantly louder, has more flash (can be tamed with FH) and look here http://www.ammo-oracle.com for info on 16 vs 20 for velocity and power at various ranges, I was suprised that the 16 was at 100 yrds similar to the 20 at 150. To me, with such a velocity dependent round it might matter. Everything is a tradeoff.

Zak Smith
July 14, 2005, 12:11 AM
Don't get too wound up in muzzle velocity between 16" vs. 17 vs. 18". It really doesn't make that much difference.

If you need the shortest, most handy, non-NFA carbine, then get a 16". If you're going to shoot NRA High Power, get a 20"; varmints, get a heavy 24". If you really want a rifle length gas system, get a 17 or 18". If you want long handguards, but a short barrel, put a FF rail system or tube over a low-pro gas block (like my 18" pictured-- it has a midlength gas system 'cause it's in 6.8SPC).

I've shot my lightweight 17" MSTN upper vs. my 20" mid-weight JP race-gun on the same 3Gun rifle stage out to 400 yards and there was virtually no difference in time/score (same optics, same trigger).

FWIW, the team that won the International Tactical Rifleman Championship last year (carbine 0 - 360 yards, bolt rifle 150 - 700 yards) used a 16" stainless Rock River upper (midlength gas).

Think about what twist rate you want for your barrel. 1:9 is standard for up to 69gr. You need 1:8 to stabilize the 75 and 77gr loads, which are the preferred ones for self-defense / anti-personnel.

As for report/flash-- it's a rifle, get over it. If you want more muzzle control, get a good comp. If you want it quieter, use an A2, Vortex, or Phantom flash-hider. If you want it quiet, submit a Form 4 and get a suppressor.

If you want something custom made to your specs, look at some of the vendors on AR15.com. I highly recommend MSTN, GandRTactical, and some others.


July 14, 2005, 12:57 AM
+1 on GandRTactical. I didn't get a rifle built by him, but he took the time to give me no-bull answers to questions I had and purchasing through him is quick and easy. Sounds like you're going to end up with a custom upper but you can probably purchase a complete factory lower unless you're thinking of tinkering with that too.

Zak is back with his deck shots. The one with the paintjob blends into the wood. I bet you go plinking inconspicuously on the deck :D

July 14, 2005, 11:52 AM
Thanks, Zak.

November 22, 2005, 08:13 PM
IM sent to Zak :)

November 22, 2005, 08:31 PM
Link (http://www.ar15.com/forums/topic.html?b=7&f=22&t=303646)

Here is a link to arfcom's equipment exchange. I was looking at 20" uppers and noticed an 18" with middy gas system.

New MOD4 18" SPR w/Mid-Length Cas System. Barrel is a medium contour and is Chrome Lined 1/7 w/A2 Hider. This upper comes with tapered or oversized handguards and is complete with bolt, carrier and charging handle . CMMG semi auto bolt carriers have the shrouded firing pin and a larger lug on the rear. Upper receivers are "T" marked and include extended feed ramp cuts. 5.56 chamber. New features include, "F" marked FSB and parkerizing under base. When ordering with optional gas block barrels will not be drilled for taper pins.

Zak Smith
November 22, 2005, 08:34 PM
While it is certainly possible to build a reliable and accurate upper one's self, if you happen to get a barrel that just won't shoot, you are basically SOL. Nowadays, I recommend buying from a vendor who knows how to build accurate field reliable uppers, and who will guarantee accuracy or he'll fix it. My favorite vendors are MSTN and Noveske.

Also note that a rifle length gas system will be smoother than a mid length, and can run as short as 17" barrels.

November 23, 2005, 02:29 PM
After the ban ended, I had a my 20" Bushmaster barrel trimmed back to 18" and threaded. I swaped to a flattop upper at the same time. I'm still on the fence on colapsable vs. fixed stock. I'd love to get a float tube. Is that a PRI Zach?



Zak Smith
November 23, 2005, 06:53 PM
The pictured round tubes are PRI. If you want rails, the LaRue cannot be beat.

November 24, 2005, 12:43 PM
If you want rails, the LaRue cannot be beat.

Why do you say this? One of the things I love about the PRI is that you can put the rails anywhere you want, in all sorts of custom configuations. I like having a couple of rails near the muzzle, but a round, grip-tape covered handguard near the chamber. PRI offers the best of both worlds, with LaRue (and all other railed free float tubes), you have to use those rail cover things to get a comfortable grip (unless you go with the vertical grip).

Zak Smith
November 24, 2005, 12:50 PM
You don't actually NEED rail covers for a railed fore-end. It's a rifle, not a luxury recliner. :D A LaRue rail without covers is surprisingly slim.

I do like that rails are somewhat configurable on the PRI, but it is at the expense of more parts and more possibility of movement.

November 24, 2005, 01:16 PM
I do like that rails are somewhat configurable on the PRI, but it is at the expense of more parts and more possibility of movement.

hmmm, I've never really worried about or had any problems with the PRI rails moving around on me, but then again I tighten the living daylights out of them and use red loctite. Although I suppose, all things being equal, the LaRue rails are less likely to move. What about the weight... the rifle length PRI CF tube (even with a couple of rails) is damn light; what does the rifle length LaRue rail weigh in at?

Zak Smith
November 24, 2005, 01:20 PM
Depending on how many rails you have installed and whether or not the barrel nut is steel or aluminum, a rifle length PRI tube will weigh between 11 and 19oz.

Chris Rhines
November 24, 2005, 05:10 PM
You don't actually NEED rail covers for a railed fore-end. At the risk of disagreeing with our esteemed Zak, I once shot a 3-gun match with a YHM full-length quad-rail tube, no covers. Never freakin' again. At the end of the day, my left hand looked like I had stuck it in a lawnmower. There is still a little rust on the barrel where I bled on it. Uncool.

You can get low-profile ladder type rail covers, which do a good job of taking the edges off the rails without adding a lot of bulk.

I will agree that if you gotta have ther quad rails, the LaRue is the way to go. For me, I prefer the new model JP handguards, with a short section of rail at 1:30 and another at 9:00. The JP-VTAC handguards attach to the barrel nut with seven screws rather than with threads, which seems more solid. They're also very comfortable to shoot.

- Chris

Zak Smith
November 24, 2005, 10:29 PM
Yep, I think the abrasiveness depends somewhat on the particular type of rail used. I can use a LaRue without panels, but YMMV as always.

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