The story of the mid-length AR-15, what is it?

[556slinger]

I have always had an eye for the mid-length platform. So, I built one but as far as having any knowledge about them, well... I don't. After searching for info and retailer websites as the only results i gave up. now I come to you guys in hopes that one can help me out. What is the history, special purpose, military or LE issued?

[Vismund Cygnus]

I think it was meant as a compromise between the longer barrel of the M16 and the quicker handling of an M4.

[LightningMcQueen784]

My thought and understanding on it was that the mid-length offers the gas system of a full length rifle, while maintaining the handling characteristics of the shorter carbines (no bayonets tho). it's kind of a compromise, but one that sounds quite attractive.

But someone please correct me if I'm wrong...

[mojo]

Mid length gas length does not equal rifle length. Mid is longer than carbine but shorter than rifle. I forget the actual measurements but this is what I think they are:

Carbine: 7.5 inches
Middy: 9 inches
Rifle: 13 inches

[DaveM55]

Stolen from another site:
http://forums.officer.com/forums/showthread.php?t=81462

GAS SYSTEMS OF THE AR-15 FAMILY

There are three types of gas systems for the AR-15 rifle: carbine, midlength and rifle. This is referencing the gas system, not the sight radius (distance of the front sight from the rear sight.) The gas system is composed of the gas port (located under the front sight base), which the gas block covers and redirects the gas back into the upper receiver through the gas tube. The handguards cover up this tube which is just made of thin aluminum. The M16 utilizes a rifle length gas system, and has 12" handguards. The midlength uses (you guessed it) a midlength gas system (9" handguards), and the carbine (M4, CAR-15) uses (that's right) the carbine length gas system (7" handguards.)

Carbine

An intersting note in regards to gas systems, is that the carbine length system was designed to be used with 11.5" barrels (Colt Commando.) When the M4 stuck a 14.5" barrel on there (and commercial manufacturers used 16" barrels) it makes the short gas system extremely harsh on the carbine, leading to the symptom of "hard extraction." To overcome this, a bolt upgrade is needed. The bolt in a carbine should have a black insert under the extractor spring. This helps the symptom, but commercial manufacturers went further and fixed the PROBLEM, not just the symptom when they created the midlength.

Midlength

The "middy" is less harsh on the action, resulting in smoother extraction like its big brother, the rifle gas system. The middy naturally gives the shooter a longer sight radius than the carbine, but not as long as the rifle. It's an excellent compromise if you are going to run a 16" barrel, and it is even the correct dimensions (length from flash suppressor to FSB) for the USGI bayonet to fit!

Rifle

As mentioned, the rifle is the original gas system used in the M16, and is the best. However, it necessitates the use of an 18"+ barrel, and that is getting too long for most LE work. But if you're one of those rural deputies, and you have plenty of room in your squad/truck for one, go for it. The extra barrel length will increase the velocity of your bullet, and that's always a good thing. It would not fit well in my vertical rack, so I carry a 16".

[556slinger]

nice, thanks for the info. now, I don't feel like such a bone head with the whole not knowing the background of my rifle.

[Willie D]

...while maintaining the handling characteristics of the shorter carbines (no bayonets tho).

Actually, you CAN put a bayonet on the mid length, but you can't put a grenade launcher on one.


I bought a Delton mid length for the supposed improved reliability over the M4 style and because the sight radius is longer. I haven't been disappointed.



Another option would be the "Dissapator" carbine, which has full length handguards over a mid lenth gas system.

[556slinger]

Well, I gave the middy a little test today. I ran 300 rounds of brown bear 62 gr. hp lacquered steel cased surplus and there was not a single malfunction. Surprisingly, it was pretty accurate.. a bit dirty but accurate. I had a very enjoyable 3 hours today. Its been a while since me and the wife did something fun alone without the kids.

[drose40]

Its been a while since me and the wife did something fun alone without the kids.

Ah, that begs for a snappy, funny response. But I'll control myself and leave that for another. ;-D

[556slinger]

Its been a while since me and the wife did something fun alone without the kids.

Ah, that begs for a snappy, funny response. But I'll control myself and leave that for another. ;-D

haha, now that you bring attention to it lol