PDA

View Full Version : Difference Between Mid-Length and Carbine?


Durwin
02-19-2012, 5:38 PM
Good Evening all,
I'm looking for a Daniel Defense barrel for the AR that I'm building.

I'd like to know the difference between the mid-length and carbine-length versions. They are both 5.56 and 16". Is there a difference in gas tubes or in the way handguards will mount?

Does one have an advantage over the other?

Thanks, D

takinflight33
02-19-2012, 5:43 PM
the differnce is the length of the gas system. the midlength gas system is longer which makes for a smoother recoil pulse when fired.

Dhena81
02-19-2012, 5:48 PM
Good Evening all,
I'm looking for a Daniel Defense barrel for the AR that I'm building.

I'd like to know the difference between the mid-length and carbine-length versions. They are both 5.56 and 16". Is there a difference in gas tubes or in the way handguards will mount?

Does one have an advantage over the other?

Thanks, D

It's a difference in length carbine 7" midlength 9" so if you have a drop in handguard there will be a difference.

Arkangel
02-19-2012, 5:48 PM
Good Evening all,
the way handguards will mount?

Does one have an advantage over the other?


You will need midlength handguards

the differnce is the length of the gas system. the midlength gas system is longer which makes for a smoother recoil pulse when fired.

Pretty much nailed it. That's the short and to the point version.

Durwin
02-19-2012, 6:16 PM
Thanks everyone.
The handguards will be Vltor.

Durwin

clutchy
02-19-2012, 7:02 PM
the idea behind the midlength gas system is that it mimics the length of the gas systems of other barrel lengths.

the carbine(7") was designed for a 14.5 inch barrel.

the midlength then gives you the same gas length with a 16" barrel or something like that.

Most people put a 16" barrel on their gun and then you end up with a 7" gas system on a 16" barrel which evidently gives you alot more pressure in the chamber and in the recoil system. More pressure than is needed. The reason is that after the bullet passes the gas tube you still have X amount of barrel which continues to send more and more gas through the system. Moving the gas port forward on the middy gives you a similar length system to a 14.5" barrel w/ a 7" system.


there's a whole huge argument about it...

make sense?


< - Now ask this goofball why he put a middy system on his 14.5 :(

jbush
02-19-2012, 7:13 PM
the idea behind the midlength gas system is that it mimics the length of the gas systems of other barrel lengths.

the carbine(7") was designed for a 14.5 inch barrel.

the midlength then gives you the same gas length with a 16" barrel or something like that.

Most people put a 16" barrel on their gun and then you end up with a 7" gas system on a 16" barrel which evidently gives you alot more pressure in the chamber and in the recoil system. More pressure than is needed. The reason is that after the bullet passes the gas tube you still have X amount of barrel which continues to send more and more gas through the system. Moving the gas port forward on the middy gives you a similar length system to a 14.5" barrel w/ a 7" system.


there's a whole huge argument about it...

make sense?


< - Now ask this goofball why he put a middy system on his 14.5 :(

This^ The dwell time, (time the bullet pass the gas hole to the end of the barrel) is more optimal in a 16" midlength. The carbine length system was designed with the shorter 14.5" barrel, by adding an 1 1/2 to make it a 16" barrel the gas port is moved out on a mid length. Check ar15barrels.com for specs on optimal dwell time. Although there are a lot of AR owners who swear by their midlength 14.5 barrels. Not going there right now.

Agent Tikki
02-19-2012, 8:11 PM
Midlengths give you 2 inches more rail/handgaurd to use, and 2 inches more sight radius.

Carbines are lighter.

Midlengths also look nicer imho.

Since most manufacturers overgas their systems, the whole middys shot softer thing is a pretty minor point imo.

tuna quesadilla
02-19-2012, 8:29 PM
Chevy vs. Ford
Bud vs. Coors
Coke vs. Pepsi
...
Midlength vs. Carbine

It's one of those questions that people will viciously fight for their respective side, but the truth is both can be just as good.

People talk about dwell time being optimal with 16" midlengths and that 16" carbine systems are inferior... Well, I happen to know of some very famous carbine instructors who use 14.5" midlength and 16" carbine gas systems. In fact the current "gold standard" of carbine AR15s, the Colt 6920, is a 16" carbine gas system.

The only practical differences between the two are:

1. Midlength has slightly longer iron sight radius (nonissue if you're using optics or a low-profile gas block)
2. Midlength gives you slightly more real estate on the handguard (nonissue if you're using low-profile gas block with a free float handguard)

Buy whichever one you can get a better deal on from a reputable manufacturer.

ETA:

3. Midlength supposedly shoots ever-so-slightly softer than carbine. From personal experience, the difference is so minimal that you would have to be one hell of a shooter for it to actually hinder you.

nitroxdiver
02-19-2012, 10:04 PM
I personally cannot feel the difference between the two. I do notice a difference with the KAC sr-15, but it also has an even longer gas system, between midlength and rifle length with 16" bbl.

Of the 2, I prefer midlength for the simple reasons that the handguard is longer, and they are more aesthetically pleasing to me. Maybe a stupid reason, but it's my preference.

vintagearms
02-19-2012, 10:26 PM
You will appreciate the additional space on the rail/handguard when shooting over a long period of time. I can tell the difference between the carbine and midlength. That is why I chose 14.5" midlength. Now if you do choose a middy I suggest you look at the carbine buffer over the rifle length especially with shooting underpowered ammo like Wolf.

Colt-45
02-19-2012, 11:51 PM
This should help:

http://www.03designgroup.com/technotes/carbine-vs-mid-length-gas-system

sonnyt650
02-20-2012, 6:31 AM
A carbine shoots gas through the gas tube a couple of inches earlier than a mid-length, and so the rest of the system needs to compensate by having a bigger buffer, stiffer action/recoil spring, reducing the amount of gas flowing, etc. It's only about the barrel out to the gas tube, doesn't matter the overall length of the barrel that way. In fact I think 14.5" properly fixes a bayonet on a carbine, while mid-length was configured to properly fix one w/ a 16" barrel as the reason why we just don't have dissipator/rifle-gassed carbines.