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View Full Version : AR 15 upper midlenght or M4 carbine gas system?


Vsanzbajo
10-08-2009, 2:40 PM
I know it is a very broad questions, but this is the deal. I can only keep one upper. Both Uppers have a 16' barrels.
I will be using the AR for self defense and target shooting at the range. I have a mid-length upper with the 9 inch hand guards and one with the shorter gas system, 7 inch hand guards.
Which would you keep, overall which one is better for a broader spectrum of tasks?
Thanks

ar15barrels
10-08-2009, 2:46 PM
The mid-length is better.

technique
10-08-2009, 2:46 PM
I honestly prefer Carbines over anything. A fine tuned 16in Carbine is a fine weapon. And its in line with "mil-spec" a mid is not. Its more of a commercial market thing.

A mid will probly last you longer, its "softer" on parts that wear over time. So I guess if you can only have one, do a mid. You may get more life from it.

THT
10-08-2009, 2:49 PM
Midlength has a longer sight radius, easier on parts, and softer recoil.

StevieC
10-08-2009, 4:44 PM
would that be like a dissipator?

Vsanzbajo
10-08-2009, 4:48 PM
What do you mean by dissipator?

Vsanzbajo
10-08-2009, 4:49 PM
I can only have one for now. Moving soon, do not want to overhaul too much.

ar15barrels
10-08-2009, 4:51 PM
What do you mean by dissipator?

Dissipator is a carbine length handguard with a low profile gas block and rifle length handguards.

http://img14.imageshack.us/img14/6002/dissybarrel.jpg

tomd1584
10-08-2009, 6:17 PM
Dissipator is a carbine length gas system with a low profile gas block and rifle length handguards.



fixed

J_Rock
10-08-2009, 6:37 PM
16" - midlength
14.5" or shorter - carbine length

Afterburnt
10-08-2009, 6:51 PM
Dissipator is a carbine length handguard with a low profile gas block and rifle length handguards.

http://img14.imageshack.us/img14/6002/dissybarrel.jpg

What is the advantage of this set up?

technique
10-08-2009, 6:56 PM
What is the advantage of this set up?

longer sight radius ...

THT
10-08-2009, 7:21 PM
16" - midlength
14.5" or shorter - carbine length

Barrel length doesn't dictate gas system length. There are many 16" barrel midlengths as well as carbines.

tomd1584
10-08-2009, 7:26 PM
Barrel length doesn't dictate gas system length. There are many 16" barrel midlengths as well as carbines.

i think what he was trying to say is, if the barrel is 16", run a midlength. for 14.5" or shorter, run a carbine.

technique
10-08-2009, 7:27 PM
Barrel length doesn't dictate gas system length. There are many 16" barrel midlengths as well as carbines.

He's talking what barrel length is optimum for what system. Although messing with port size really makes that irrelevant.

jasonnorcal
10-08-2009, 8:20 PM
Dude, that thing looks badass:43: Gonna have to do a quick google search to see a complete dissipator

J_Rock
10-08-2009, 9:15 PM
i think what he was trying to say is, if the barrel is 16", run a midlength. for 14.5" or shorter, run a carbine.

Bingo.

And yes you can have a 14.5" midlength. They are exceeding hard to find or you would have to cut a 16" midlength down and open up the gas port.

ar15barrels
10-09-2009, 9:48 AM
fixed

Thanks.
Fingers were not typing what mind was thinking.

LongRangeShootin
11-05-2009, 12:32 PM
one of my rigs is a custom 18" heavy barrel (1" under free float tube). it has its gas block thats only like 4" from the end of the barrel, and works
B-E-A-U-T-I-F-U-L.

http://img.photobucket.com/albums/v291/johnsguns/DSCF3161.jpg

1988
11-05-2009, 12:36 PM
I honestly prefer Carbines over anything. A fine tuned 16in Carbine is a fine weapon. And its in line with "mil-spec" a mid is not. Its more of a commercial market thing.

A mid will probly last you longer, its "softer" on parts that wear over time. So I guess if you can only have one, do a mid. You may get more life from it.

IMHO, the longer gas length is better. However, I believe that they had to use the Carbine length for the M4 because they need room for the bayonet and launcher.

ar15barrels
11-05-2009, 12:40 PM
one of my rigs is a custom 18" heavy barrel (1" under free float tube). it has its gas block thats only like 4" from the end of the barrel, and works

That's because it has a rifle gas system.
Rifle gas systems almost always work better than both mid-lengths and carbine gas systems given a similar amount of barrel past the gas port.
This is because the rifle gas system has more TIME for the bullet to get out of the barrel before the bolt unlocks and tries to extract the case.

jasonnorcal
11-05-2009, 2:57 PM
OP, you should keep the middy for sure, even though I want a carbine:shrug:

missiontrails
11-05-2009, 8:23 PM
I honestly prefer Carbines over anything. A fine tuned 16in Carbine is a fine weapon. And its in line with "mil-spec" a mid is not. Its more of a commercial market thing.

A mid will probly last you longer, its "softer" on parts that wear over time. So I guess if you can only have one, do a mid. You may get more life from it.
+1. Went through a mid-length stage, now back to carbines with right combination of gas/buffer weight..

missiontrails
11-05-2009, 8:26 PM
Bingo.

And yes you can have a 14.5" midlength. They are exceeding hard to find or you would have to cut a 16" midlength down and open up the gas port.

This is a CMMG 14.5" mid-length:
http://members.cox.net/mephoto/CMMG.jpg

ko1featherweigh
11-05-2009, 9:28 PM
What about the pigtail gas tube any advantages to that? or would it be better just to get a midlength?

ar15barrels
11-06-2009, 2:01 AM
What about the pigtail gas tube any advantages to that? or would it be better just to get a midlength?

They have problems distorting with heat.
Get a proper midlength.

lumpia
11-06-2009, 3:08 AM
I know it is a very broad questions, but this is the deal. I can only keep one upper. Both Uppers have a 16' barrels.
I will be using the AR for self defense and target shooting at the range. I have a mid-length upper with the 9 inch hand guards and one with the shorter gas system, 7 inch hand guards.
Which would you keep, overall which one is better for a broader spectrum of tasks?
Thanks

Personally I prefer the mid. That being said, I'd rather have a BCM carbine than a Stag mid (if Stag even makes a mid, I wouldn't know). What brand are your uppers?

vinny_land
11-06-2009, 10:31 AM
Personally I prefer the mid. That being said, I'd rather have a BCM carbine than a Stag mid (if Stag even makes a mid, I wouldn't know). What brand are your uppers?

You're right...Stag doesnt make midlength. As for the dissipator, i believe CMMG and DPMS make them (also Model 1). If Im not mistaken, CMMG markets the dissipator with all three gas systems but all with the rifle sight radius.

Rule .308
11-06-2009, 10:45 AM
I have a disipator set up that is probably 20 years old and it just runs a rifle length gas system, has worked flawlessly for me for many years.

bombadillo
11-06-2009, 2:59 PM
BCM mid length!! FTW

Vsanzbajo
12-17-2009, 5:20 PM
BCM BFH midlenght upper.

NiteQwill
12-17-2009, 5:44 PM
BCM BFH midlenght upper.

Hell yea. That's what I run and I love it.

bombadillo
12-17-2009, 9:09 PM
Oh, I have a 16" BCM mid length gas system upper and a JP 18" rifle length gas tube, and a 20" rifle length gas tube and I have NEVER had a failure to anything other than fire and that was my own fault with super super lightweight springs that I put in. Hope you get what you want!

-B