16" Rifle-Length vs. 20" Rifle-Length AR15


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P.B.Walsh
May 29, 2009, 07:19 PM
I'm looking at a 16" Dissapator, and 20" std. length from DPMS, and wanted to know which one is more reliable?

I like them both, I like the way the 16" bbl. is not showing. But the 20" bbl. allows a boyonet (for HD).

These rifles will be used for HD, target shooting, a d close range hunting, and I will add a Viking Tactical Rifle-Length handguard also.

Please help me out. Their both under 1k from DPMS with my custom option a that I added.

Thanks :)

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Avenger29
May 29, 2009, 07:33 PM
I don't even own a bayonet for my AR-15. Not only can I not use it, they suck as blades anyway.

You're sticking a VTAC handguard on it. That means the gas block is coming off anyway for install. I'd put a low profile gas block (pinned) under the hand guard and put a fold up sight on the top of the VTAC handguard, like the example below. I'd do that for either a 20" or 16" barreled rifle. You could even probably (depending on the barrel profile) stick a gas block/FSB out there to allow for a bayonet if it's that important to you. The Bushmaster Dissapator, for example, uses a carbine length system with the gas block under the handguards and a front sight base out in front.

A 20" barreled AR would be a little more unwieldy for close quarters than a 16", but wouldn't be absolutely horrible. I'm hankering for a 20" barrel AR as my next one.

http://img9.imageshack.us/img9/818/img190520102820stick.jpg
(Stickman has some of the best AR photography out there.

P.B.Walsh
May 29, 2009, 07:53 PM
Well this is my first AR. What does "pinned gas block" mean?

Is that a 16" above? A bayo. isn't important, function is better than looks, IMHO.

What type of gas-length does re DPMS dissapator use, 'cause if it ain't mid, or rifle, then I don't want it.

Again thanks :)

Dr. Tad Hussein Winslow
May 29, 2009, 07:57 PM
This may help:

http://www.thehighroad.org/search.php?searchid=6075921

I've got one of each, so I'm not much help. But if I kept just one, it'd be the 20". The 20" will likely be more reliable over the long haul, due to the dissipater having the carbine gas system.

lvcat2004
May 29, 2009, 07:57 PM
wanted to know which one is more reliable?

Last I checked barrel length doesn't have much to do with reliability.

okcwizzard
May 29, 2009, 08:09 PM
Rifle length gas system vs Carbine gas system really isn't an issue, Both are robust enough for the task.
The DPMS dissapator has the rifle gas system, So that shouldn't be an issue. The Bushmaster dissapators and Adco dissapator builds have the carbine gas systems.(I've had both) As far as reliability goes the length of the barrel wont make any difference. Just go with the style/length that works for you.

As far as a bayo.. I just happen to have one the fits the dissipator, More of a novelty than anything

Avenger29
May 29, 2009, 08:13 PM
Last I checked barrel length doesn't have much to do with reliability.

Gas system length, however, does.

Well this is my first AR. What does "pinned gas block" mean?

Pinned means the gas block has pins that go through grooves cut in the barrel. It's the best option to secure the gas block, verses say, a gas block tightened down by set screws or a cross bolt like many are.

P.B.Walsh
May 29, 2009, 08:27 PM
So, can you pin a gas block on a 20" bbl?

I need to handle both before I buy.

Thanks :)

P.B.Walsh
May 29, 2009, 09:33 PM
Bump.... :)

Avenger29
May 29, 2009, 09:36 PM
So, can you pin a gas block on a 20" bbl?

It is generally how they come from the factory. You'd be driving out the pins and removing the gas block/FSB to install the VTAC handguards. Or you can also grind of the front sight and make the factory gas block a low profile gas block. I haven't handled a VTAC to see if you could install it like that.

Putting a gas block, say for use as just a front sight base, forward of the actual gas block will depend on barrel contour and such.

See those two holes under the front sight/gas block?

http://img16.imageshack.us/img16/6836/gasport2c.gif

It'd be much easier to explain this kind of stuff in person with an AR or two to demonstrate with. I didn't know what the hell all this stuff about "gas blocks","gas keys", "staking", "castle nut", etc was when I was first researching purchasing an AR-15. I also didn't know what brands were what and such.

Thankfully, I took a couple of years and just read everything I could about the AR-15, doing serious in depth research, handling as many examples as I could, etc.

In fact, I pretty much purchase all of my guns in this manner. It took me two years to decide on a nice .22 rifle to step up to from my Ruger 10/22. Two years to decide on an AR-15. About a year to decide on a shotgun. Two years and counting to decide on handguns (I have not decided on that yet. I've got a Ruger Security Six doing yeoman duty as a general purpose handgun until I get my CCW permit).

I'd say that the research is worth it. All the firearms I have done serious research to select have not disappointed in performance, reliability, or accuracy.



.

P.B.Walsh
May 29, 2009, 09:48 PM
Ok, I think I'm going with the 20" bbl. for the added velocity.

These are the options i'm getting from DPMS (this is on a Classic 20" from DPMS):
A3 Flatop
Ergo Ambi Grip
Chrome BCG

Is this good? Or should I opt for a Titainium Nitrade BCG

Thanks :)

telomerase
May 29, 2009, 09:56 PM
Ok, I think I'm going with the 20" bbl. for the added velocity.

It won't blow your eyebrows around with the blast as much, either....

Avenger29
May 29, 2009, 10:05 PM
Is this good? Or should I opt for a Titainium Nitrade BCG

I wouldn't waste the money. Chrome will be just fine...

P.B.Walsh
May 29, 2009, 10:05 PM
Well, I've fired a right-handed 16" bbl. AR back when I shooter as a lefty and there was no muzzel blast. (But of couse it was my first time shooting an AR15 and I was even shaking while I shot because I was SOOOOO excited, and probaly didn't notice anything but how unaccurate I was, I also accidently touch the barrel after about 15 rounds, oops, but I didn't care because I was so excited).

So I don't care about that factor, but thanks any way for pointing that out, still something to concider though.

Chrome it is, save money too. :)

Thanks :)

Avenger29
May 29, 2009, 10:27 PM
The AR-15s do have a nice muzzle blast especially if you are standing to either side. I don't notice it when firing, but as a spectator...

I'm going to be shopping for a supressor sooner or later...I think one would be a lot of fun.

P.B.Walsh
May 29, 2009, 10:28 PM
well, that's probaly why then.

jpwilly
May 30, 2009, 10:22 AM
Hey PB. You'll find the only reasons to go shorter bbl in the AR platform if for lighter weight / better handling. Getting in and out of vehicles and cutting the pie indoors makes the carbine versions a must.

But for the rest of us a 20" bbl will offer more velocity and therefore range and energy from the 223. Like many out there you'll either end up with multiple upper halves or multiple AR-15's. I have 3 DPMS rifles all are reliable and above average accurate. Whatever you build I'm sure you'll be happy.

Chrome BC Group is fine but IMO not necessary. My standard BCG's are easily cleaned after range sessions (or not even cleaned for a while).

The option for a chrome lined barrel and chamber will be more important to reliability than the chrome BC.

Uncle Mike
May 30, 2009, 10:52 AM
It took me two years to decide on a nice .22 rifle to step up to from my Ruger 10/22. Two years to decide on an AR-15. About a year to decide on a shotgun. Two years and counting to decide on handguns (I have not decided on that yet. I've got a Ruger Security Six doing yeoman duty as a general purpose handgun until I get my CCW permit).

...Yea, it sucks doesn't it... I'm the same way and I sell the damn things every day!:what:

should I opt for a Titainium Nitrade BCG

Avenger... if he doesn't show up at the range with a fancy pants, super sexy yellow colored bolt, how in the world is he going to keep up with the p3n1s envy thing that plagues our shooting ranges? hehehe :eek:

P.B.Walsh
May 30, 2009, 01:04 PM
So, a chrome barrel is more important than the BCG?

Wouldn't that make the rifle less accurate?

Thanks

Uncle Mike
May 30, 2009, 02:19 PM
Chrome is not so accurate as is a chrome moly barrel.

P.B.Walsh
May 30, 2009, 02:51 PM
So, do I NEED to get a chrome moly bbl.? I'll be putting no more than 300 rounds down the barrel per year, and accuslly closer to 200 rounds per year, so do I need a chrome moly bbl.

Thanks :)

Uncle Mike
May 30, 2009, 02:59 PM
Are you shootin' in a big money compitition?

If not then get which ever is cheapest... yea, I said cheapest.... which could be the chrome plated barrel.

The chrom-moly barrels are found more, but not exclusively, on National Match rigs, DMR's, varmint rigs ect.... :D

I would get the chrome plated barrel.

And... 200-300 rounds per year.... yea right... more like 2000-3000 rounds per year, yep, they are that much fun!

P.B.Walsh
May 30, 2009, 03:13 PM
Ok, thanks, I'll just get the A3 option, does anyone know the estimated time DPMS can ship a rifle?

ARNETT44
May 30, 2009, 05:35 PM
There should be no reliability issues with the 16 or 20. Accuracy may be slightly better with 20, but what is the twist? What ammo is being used. Sounds like you should go with what appeals to you the best.

P.B.Walsh
May 30, 2009, 07:39 PM
Ok, does anyone know what the ETA on DPMS AR15s?

railroader
May 30, 2009, 09:55 PM
Chrome lined barrels usually cost around $40 to $50 more than chrome moly barrels. Unless you are into match accuracy you aren't going to notice the difference. Chrome lined barrels last longer, are easier to clean and tend to have less extraction problems. I have to 16" barrel rifles that are both chrome lined and they run perfect. Accuracy is good too. My midlength rifle has shot groups a hair over 1" at 100yds for me so I'm happy. Mark

ArmedBear
May 30, 2009, 11:56 PM
tend to have less extraction problems

Note that this is probably the bane of the AR platform. I wish I'd gone with chrome-lined for that reason.:)

weet
September 23, 2009, 04:04 AM
hummm ? i guess , im kinda like the poster a few posts above, checked everthing out for a long time.....
then got a flattop bushy in a farm trade... wasent exactly what i wanted,, 16'' barrel carbine style.....m4
i loved the rifle sights on the rifle my buddy has....and the softer ? cycle of the rifle length gas system,
but his barrel was to long around the pickups, and on and off a farm tractor.
then ,? lo and behold, !!! eureka !!!!
the ''DISSIPATOR !!!!'' so i ordered a 16'' mid-contour ,barrel with the mid-length gas system.....think about this ?
rifle length sights, mid-lenth gas, and handy like the carbine...and even looks good with a2 stock, or the six position,
isent this ''the perfect AR?''.......... i thinks so, cannot wait to try it out.

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