Differences between M4, Carbine and Midlength

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[ARCHIVED THREAD] - Differences between M4, Carbine and Midlength

Posted: 9/6/2005 6:13:49 PM EDT

I know the difference between the M4 and Carbine: M4 profile has a distinct step-up and -down profile as well as fat handguards. Carbine can have a thin barrel or heavy barrel as long as it has a 16" lenth and thinner handguards of the same lenth as M4.

Do I have that right?

So, what is the difference between Carbine and Midlength? I understand the Midlength has 16" barrel.

Posted: 9/6/2005 6:18:53 PM EDT

[#1]

sure

carbine vs. midlength: different gas tub length--the midlenght runs the size bt/w a carbine size tube (7in) and the rifle length (12in)

so w/ the midlength, you have more sight radius, longer gas tube, longer HGs, but same 16in/14.5in +perm muzzle device as the carbine

overall, i like the middy better, hell it even looks better

**edited, thanks combat jack for the correction!**

Posted: 9/6/2005 6:19:51 PM EDT

[#2]

Midlength is a measurement of the gas system. It's longer than the carbine but shorter than standard length rifle.

ETA: Oops, AG just beat me to it.

Posted: 9/6/2005 6:20:07 PM EDT

[#3]

well I'm not an expert on the subject, but a true M4 has a 14.5 inch barrel (i believe), and is still a carbine. The difference between the carbine and the midlength has to do with the midlength having a longer gas tube, longer hand guards, and a longer sight radius....but someone correct me if this is wrong

Posted: 9/6/2005 6:21:21 PM EDT

[#4]

Its a little more complicated than that.

Carbine is any barrel from 14.5 to 16 or so, or in some references 18".
M4 is actually a barrel profile, and can be 14.5 or 16". Its the one thats light under the handguards and has the M203 mounting turndown in front of the front sight base.
Mid length is a length of gas system and the corresponding handguards. 12.5, 14.5, 16 and 18" barrels can and sometimes do have midlength gas systems.

Handguards on a carbine or M4 are 7 inches long. On a midlength they are 9 inches. Full size rifles use 12 inch long handguards.

ETA: An M4 and a mid length are also considered carbines, but normally the distinction that they are "M4 carbines" or "Mid length carbines" is made. In the above list, consider the term carbine to mean a non M4 barreled rifle with a standard 7 inch gas system.

Posted: 9/6/2005 6:21:43 PM EDT

[#5]

A midlength 16" barrel has a longer gas system-the port is closer to the muzzle than the port on a carbine, so the gas impulse is both slightly later in the cycle and relatively softer than in a carbine.

Basically the "distinguishing features" of the M4 series are the barrel profile (which is designed to allow the attachment of an M203 grenade launcher IIRC), the carbine-length gas sytem, and the distinctive handguards (which, to be correct, should have double heat shields).

Posted: 9/6/2005 6:23:33 PM EDT

[#6]

The prinsipal difrense is the lenth of the forgrip...allowing for a longer "radius" on the front sight (full length handgaurds can be used on a 16"-barreled midlength, but not a 16"-barreled carbine).

Carabine

Midlenth

Posted: 9/6/2005 6:27:18 PM EDT

[#7]

Quoted:
The prinsipal difrense is the lenth of the forgrip...allowing for a longer "radius" on the front sight (full length handgaurds can be used on a 16"-barreled midlength, but not a 16"-barreled carbine).

I have to disagree with you here. My middie's handguards are shorter than full length handguards, but signifcantly longer than carbine handguards.

Basically the front sight is about the same distance from the muzzle as on a 20" barrel, so that means that the handguards are going to be about four inches shorter on a midlength than on a 20" rifle.

Posted: 9/6/2005 6:36:40 PM EDT

[#8]

Mid length is about 3 inches shorter than rifle. And thats a rifle gas system on the SPR clone there. And an 18" barrel.

And dude, no offense, but its principle and difference.

Posted: 9/6/2005 7:06:29 PM EDT

[#9]

Quoted:
Basically the front sight is about the same distance from the muzzle as on a 20" barrel, so that means that the handguards are going to be about four inches shorter on a midlength than on a 20" rifle.

D'OH!
Thanks for the correction! (I really didn't know that)...Always that that they were the same.

Posted: 9/6/2005 7:08:09 PM EDT

[#10]

Quoted:
Mid length is about 3 inches shorter than rifle. And thats a rifle gas system on the SPR clone there. And an 18" barrel.

And dude, no offense, but its principle and difference.

It's not Carabine or Midlenth either.
I was just being an asshat.

So, If the handguards are proprietary to midlengths, what's the appeal? (I'm not trying to knock self-expression...I think they're cool looking)

Posted: 9/6/2005 7:12:06 PM EDT

[#11]

Posted: 9/6/2005 7:18:53 PM EDT

[#12]

so comparing it to a dissipator what length is the gas tube for a mid?from gas block to end?

Posted: 9/6/2005 7:26:22 PM EDT

[#13]

Quoted:
so comparing it to a dissipator what length is the gas tube for a mid?from gas block to end?

A dissipator uses a carbine 7 inch gas system under 12 inch rifle handguards. Mid length is 9 inches.

Posted: 9/6/2005 7:34:20 PM EDT

[#14]

Speaking of reliability and gas pressure etc

Isn't it "better" to have a longer distance between the gas port and the muzzle?

for example a carbine would have roughly 9 inches of barrel past the gas port on a 16inch barrel and a midlength would have about 6 or 7 inches on a 16inch barrel - right? Are there any concerns with this?

Posted: 9/7/2005 10:53:47 AM EDT

[#15]

Quoted:
Speaking of reliability and gas pressure etc

Isn't it "better" to have a longer distance between the gas port and the muzzle?

for example a carbine would have roughly 9 inches of barrel past the gas port on a 16inch barrel and a midlength would have about 6 or 7 inches on a 16inch barrel - right? Are there any concerns with this?

No, you want the longer gas tube so that you have less pressure cycling the gun. Rifles run great, its the carbines that have all the trouble - needing heavier buffers and such to run reliably. Midlengths run at lower pressures than carbines; therefore can be more like a rifle in their reliability. Plus, they just look nice, very porportionate overall.

Posted: 9/7/2005 3:51:24 PM EDT

[#16]

So what are the advantages/disadvantages of a midlength versus a carbine? Is it just that it will cycle better as mentioned above?

I guess I'm just wondering if it is mainly an aesthetic issue or is it mainly a reliability issue?

Any clarifications are welcome. Thanks!

Posted: 9/8/2005 5:55:44 AM EDT

[#17]

Quoted:
So what are the advantages/disadvantages of a midlength versus a carbine? Is it just that it will cycle better as mentioned above?

I guess I'm just wondering if it is mainly an aesthetic issue or is it mainly a reliability issue?

Any clarifications are welcome. Thanks!

No, thats about all the midlengths have going for them over carbines, more reliable and better porportions. Midlengths will accept a bayonet, unlike a carbine. I want a midlength just because they look "right".

Posted: 9/8/2005 6:02:10 AM EDT

[#18]

Midlengths also tend to be a bit more accurate do to the fact that they cycle a little less aggressive, at least for me they are. The longer sight radius is a big plus! When you have to have a 16" barrel I dont see the reason for a carbine gas system. Now if you go the NFA route and get the SBR then 14.5" M4 carbine all the way!

Posted: 9/8/2005 7:24:20 AM EDT

[#19]

Interesting. For some reason I've only been looking at Carbine's for my next AR.....even though my only AR is also a carbine. I just might have to look into this whole midlength thing.

Thanks for the responses!!!

[ARCHIVED THREAD] - Differences between M4, Carbine and Midlength

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