View Full Version : Main differences M4 VS M16

February 9, 2010, 07:24 PM
What is the real difference between these guns, "AR15's" M16 and M4? Besides the firing options and accessories and stupid add on's. What are the real internal differences of these rifles?

February 9, 2010, 07:29 PM
Let me see if I can answer this,

The M16 in its true form is a 3 round burst and semi-auto rifle with a 20" barrel and fixed stock.

The M4 in its true form is a full auto and semi auto carbine with a 14.5" barrel and a 6 position collapsible stock and shorter hand guards. This is an ideal set up for close quarter gun fighting.

The civilian versions are obviously semi auto only and the M4 style ARs have 16" barrels with the M203 grenade launcher notch on the barrel. The full size M16 style is exactly like the military issue rifle without the 3 round burst.

The term AR-15 is a generic term to describe all M16/M4 family of semi auto rifles based on the M4 and M16.

The lowers on both are identical and will interchange.

February 9, 2010, 07:30 PM
Barrel Length, Feed Ramps, Adjustable stock on the M4, Gas tube length, Gas system Pressure, Barrel Contour, and i'm sure theres a few other things i'm missing but that seems to cover most of the major differences. Well i guess detachable carrying handle if u mean the M16A2, but the M16A4 has that.

February 9, 2010, 07:33 PM
Spyder i think you mixed the full auto vs burst up. The M4 carbine in original version is 3 round burst. the M4A1 (Advancement 1) is full auto.

The M16 however, the original model was designed in full auto (XM-15 i believe it was called at the time) and the M16A1 was Full auto, it wasn't until the A2 that it was a burst fired weapon.

February 9, 2010, 07:50 PM
Yea I knew about the firing options but was curious about the internal differences like 2nd poster stated, thanks for the info guys

February 9, 2010, 08:16 PM
I think you are right... the M4A1 is the full auto version.... too many M16 style guns can't keep em straight! :mad:

February 9, 2010, 09:30 PM
The M4 has a shorter gas tube, so it tends to have a sharper cycle rate. The buffer tube is also shorter due to the collapsing stock. To moderate some of this the M4 has feed ramps cut into the receiver and barrel extension to guide the bullet into the chamber better as it is slammed of the mag. Also, you can get heavier buffer weights like H and H2 to slow down the cycle (not much noticeable for semi auto, but probably of more use to the full auto guys).

The barrel is shorter, of course, so the front sight is made a tiny bit taller so stays in the same relative alignment with the rear sight.

I also believe it was th M4 that introduced the more oval handguards in place of the triabgular or round M16 ones.

February 10, 2010, 05:47 AM

February 10, 2010, 07:50 AM
there ya go RT!!