Barrel indention

[gunman496]

i dont mean to sound ignorant or stupid but i think i may be spelling indention wrong . . . regardless my question is what is the need for that indention on the barrel of an M4gery. if you look at this you see it:

AIM Double Star S-15 .223/5.56 M4 Rifle Double Star S-15 .223/5.56 M4 Rifle

if you look at this:

Rock River Arms: TASC Upper Half

is there a reason for that ? if so what are the benefits of it? cause i really like the looks of that rock river upper and thats probably what i'll end up going with but i want to hammer out little details first

[John A.]

The indention is one thing that makes an M4 barrel an M4 barrel.

The indention (barrel contour) is for securing M203 grenade launchers or 37mm flare launchers, or the Masterkey shotgun to the AR barrel.

Here's you some homework.
Knight Masterkey Shotgun

37MM

M203 grenade launcher - Wikipedia, the free encyclopedia

[chad_quixote]

I WANT!!!!






Knight Masterkey Shotgun

Several shotgun designs have been modified to be mounted under the barrel of combat rifles or submachineguns. The shotgun is mounted in a similar fashion to the M-203 grade launcher under the M-16. Masterkey shotguns have been mounted under the M-16, M-4, and MP-5 weapons. The Knight masterkey shotgun is one such under rifle mounted shotgun and is primarily designed as a breaching took. That is a weapon designed to blow doors open. As such, the weapon is most commonly used by law enforcement. The shotgun is part of the Knight Corporation's Modular Weapon Concept.
The Knight Masterkey has a short 10 inch barrel and is fairly lightweight at under 6 lbs. Still, a combat rifle or submachinegun can be a fairly heavy combination. The shotgun is punp action and has a three round internal magazine. One more round can be carried in the chamber when needed. Like the M-203 grenade launcher, the recoil is destributed to the host weapon's barrel nut and barrel. It also uses the rifles magazine as the handgrip to fire the shotgun. The shotgun uses an aluminum adapter to simulate the receiver dimensions of the M-203 grenade launcher. The shotgun is designed to be quickly detached and is designed with a special folding butt stock to be used independently.
Weight:5.5 lbs (2.5 kg) free weight, 9.1 lbs (4.12 kg) assembled to Stand Alone assembly.Caliber:12 Gauge.Barrel Length:10 inches (25.4 cm).Overall Length:16.7 inches (43.2 cm) free length, 29.5 inches (75.0 cm) assembled to Stand Alone assembly with butt-stock extended, & 20.7 inches (52.7 cm) with stock closed. Action:Pump Action.Mode of Fire:Single shot only.Range:300 ft (90 m).Magazine:3 round internal.Cost:1900Made in:USA.Special:Lightweight, can be mounted under the barrel of combat rifles and submachines.

[Knight, Masterkey, M-16, M-4, and MP-5 are copyright of their respective owners]
By Mischa (E-Mail Mischa ) and by Kitsune (E-Mail Kitsune). Copyright © 2002, Mischa & Kitsune. All rights reserved.