Advanced AR-15/M16 Components from VLTOR
By Christopher R. Bartocci

The entire firearms industry has appeared to enter the AR-15/M16 business, whether it is by manufacturing complete weapons, replacement/upgrade components or accessories. Some manufacturers make higher quality than others. There are military/law enforcement grade equipment and less expensive hobbyist equipment.

VLTOR was started by Eric Kincel, former staff writer for Gun World magazine and former Service Assembly Manager of Knight’s Armament Company. Kincel also co-founded Microtech Knives and led a small arms division called Unitech Research, Inc. Unitech dissolved as a company due to a lawsuit with Knight’s Armament Company. In 2001, with the assistance of an investor, VLTOR was formed. In 2004, VLTOR was bought by Abrams Airborne Mfg., Inc. This is a major aerospace contractor which brought VLTOR the advantage of their great experience with space-age materials. The AR- 15 was ground breaking in the 1950s with the advantages brought from Fairchild Engine and Aircraft in using advanced aircraft materials. VLTOR is using the next level of technology, aerospace technology and materials. This partnership between the two companies has brought VLTOR consulting, co-developing with other firearms manufactures, securing government contracts and receiving patents for their newly developed projects.

Kincel recalls seeing a press release on the Advanced Combat Rifle (ACR) Program in 1988, with particular fascination with the Colt entry. While working at Knight’s Armament, who developed the muzzle brake/compensator for the Colt ACR, Kincel got to fire the Colt entry and became very fond of some of the enhancements; in particular, the triangular cheek weld of the collapsible stock. The original ACR stock cheek weld area was filled with foam but Kincel felt that that would be a good place for a storage compartment. Kincel acquired his first ACR stock from Ken Elmore (Specialized Armament Warehouse) that was modified to fit the standard receiver extension. Later, Kincel acquired a complete original Colt ACR stock with the original receiver extension and hydraulic buffer. Development of the Modstock commenced and was released for sale in 2001. The Modstock offered several advantages over the current military issue. The Modstock is manufactured from advanced high strength glass filled polymer with a special impact modifier added to the polymer formula.

The Modstock offers three sling mounting points. First is the standard loop through the stock. The other two positions are through a reversible sling swivel. It could be placed in either the right or the left side. The key improvement was the addition of two battery storage compartments that are mounted to the top left and right side. This water resistant tube enables the soldier to carry spare batteries for his issue M68 (AimPoint) reflex sight or the 3-volt lithium batteries for the EOTech sight. Also, a cheek-weld adapter is available which could replace one of the battery storage compartments; a benefit for users who are wearing gas masks. The stock comes in two configurations: the standard and the clubfoot. The standard is similar in profile to the mil-spec stock. The clubfoot is intended more for precision shooting. The L-shape stock provides something for the shooter to hold onto when he is steadying the rifle. The clubfoot model has a special butterfly paddle compared to the standard paddle, which eliminates the possibility of snagging on web gear ending in an accidental unlock of the stock. The Modstock is offered in black, foliage green and flat dark earth. There are two rifle length Modstocks available. One A1 length and the other is 5/8 of an inch longer A2 length.

Along with the stock itself, VLTOR offered a complete assembly that included a receiver extension that had the five positions numbered and could be viewed by a hole in the top of the stock. This is a milspec diameter receiver extension. A standard carbine buffer and buffer spring is provided. Also provided is a lock plate and lock nut. This lock nut/plate uses the standard mil-spec installation wrench and may be staked in place after installation. VLTOR offers additional options in lock plates which are universal to left and right hand shooters. One lock plate provides a circular ring for a 1-point sling as well as a standard 1-inch sling mount. VLTOR also offers a similar locking plate with a small circular ring designed to fit the Heckler & Koch-type hook sling mount.

The standard stock was utilized by all three of Colt Defense LLC’s SCAR (Special forces Combat Assault Rifle). The clubfoot model was utilized on the ArmaLite SASS (Semi-automatic Sniper System) candidate as well as the early Remington SASS candidate. These stocks have become very popular with military special forces and law enforcement; particularly those who utilize battery operated optics. The Modstock was granted a National Stock Number (1010-01-536-4742) due to it being a standard item on U.S. Marine Corps M32 grenade launcher. The largest single purchase of Modstocks has been from the Canadian Forces (Special Forces).

SAR also gets a first look at a new Enhanced Modstock (EMOD) just going into production by VLTOR. This is a modified version of the clubfoot Modstock. The major differences are that is 1 inch longer than the standard Modstock. The butt plate is longer as well. The EMOD has a semipermanent rubber buttpad, which is held in by one screw. With the screw and the rubber buttpad removed, the stock can still be used. The rear of the stock is textured with diamond knurling for ensured traction. With the buttpad installed, the overall length of the stock is increased by 1/2 inch. This makes ease of installation and removal of both the removable battery compartments as well as the cheek-weld adapters. The longer storage compartment holds either four lithium 3Volt batteries or three lithium batteries and one AA battery. Additionally, there is an additional battery compartment located on the left side of the stock that will hold two AA batteries or one lithium 3Volt battery for use in optics such as the AimPoint M68 reflex sight and the Leupold CQT.

The EMOD has internal improvements as well. The first improvement is the strengthening around the locking mechanism. The second improvement is that the stock will be made to cater to both types of receiver extensions, the commercial and the military model.

The VIS (Versatile Interface Structure)

Over the past few years, many manufacturers have come up with rail system and monolithic upper receivers. The monolithic receivers have shown great promise in both durability and achieving aim point retention when removing and replacing optics. Also, the monolithic upper receivers permit a completely free floated barrel. This aids in both accuracy and cooling of the weapon during extended periods of fire.

At the 2006 SHOT Show, VLTOR introduced their VIS or Versatile Interface Structure after a 12 year development process. The VIS is made of two pieces of 6061 T6 aluminum extrusions. The reason for two pieces rather than one is so the VIS could use standard barrel assemblies unlike other monolithic handguards where you have to have a proprietary barrel assembly to install in the receiver. It is not possible to machine the barrel attachment assembly in a one-piece upper as the current mil-spec AR-15/M16/M4 barrel assembly calls for. The barrel in the VIS is completely free floated. The VIS will also accept low profile gas blocks such as the VLTOR’s, P.R.I. and LaRue in case the shooter want to run a short gas system with a longer handguard length version on the VIS. The upper receiver is manufactured from an extrusion of aluminum with a proprietary VLTOR modular shell deflector, forward assist or combination. The handguard and receiver are currently bonded together by a “Molten Salt Dip Brazing” though other methods are currently being looked at. The handguard has quad Mil-Std-1913 rails at 12, 3 and 9 o’clock and a removable lower handguard which provides a 6 o’clock rail. It is held into the receiver by two locking levers, not a slip ring or a screw. All VIS systems have M4-type extended feed ramps and any Mil-Spec barrel may be installed with an extended barrel extension.

Installation of the barrel into the receiver is quite simple. After applying some never-seize compound, the VLTOR special designed barrel nut is installed and torqued down to the no more than the mil-spec 40 pounds with the provided installation tool. The tool is then discarded as it is designed for one use. Then the gas tube is installed in the gas block/front sight tower and the assembly is slid onto the barrel. The gas tube goes through the hole in the receiver. The assembly is either staked back in place or assembled with the Allen key hex screws. Also provided is a M203 index bracket for installation after the barrel nut is torqued. The lower hand guard is then installed front end first. When it is in place, two levers are moved to lock it into place.

Currently VLTOR only offers the VIS in the kit only, not with a barrel installed. The barrel that was installed on my test and evaluation VIS was a 16 inch Wilson 1/8 twist barrel with a standard birdcage flash suppressor and crush washer. This VIS was a mid-length gas tube variation. VLTOR offers standard carbine and rifle lengths as well. A standard bolt carrier group was provided. The barrel has a VLTOR made gas block with a back up front sight that, when folded, the gas block serves as a Mil-Std-1913 rail. To engage, the front sight is lifted by the front of the assembly and locks in place. The front sight post is similar to that of an AK47 or an SKS. It is adjusted with a tool and is adjustable for elevation only. Below the sight is a ring for the installation of a removable sling swivel that can be installed from either side. The back up sight provided was Troy Industries rear folding battle sight. However, any of the A.R.M.S., Knight’s or MaTech BUIS can be used.

The optic chosen for testing is an AimPoint M68 reflex sight mounted on an A.R.M.S. throw lever mount. The mount had the A.R.M.S. spacer installed so I would have co-witness with the iron back up sights. The vertical pistol grip utilized was the Grip Pod designed and manufactured by Joe Moody. This pistol grip, by the press of a button, turns into a bipod. The height of the bipod is perfect. When laying prone the 30-round magazine will not obstruct the movement of the rifle. The ammunition chosen for test firing the VIS was M855 Ball for function ability and Black Hills Mk262 MOD1 ammunition for accuracy.

The CASV-EL Free Floating Handguards

Probably the most significant improvement to the weapon system since the development of the M4 carbine is the rail systems. This is what has really given the M16/M4 the flexibility to be as “modular” as it now is. The first system to be truly accepted by the military for general use is the Knight’s Armament Company RIS (Rail Interface System) and to that, the current issue RAS (Rail Adapter System). This replaced the handguard and replaced it with quad Mil-Std-1913 rails. This system required no modifications to the existing firearm. A bottom handguard attaches to the handguard cap and will be retained by the slip ring. These rails made the secure mounting surface for flashlights, lasers, range finders and anything else you may think of. It also brought the age of the vertical pistol grip. By removing the bottom handguard, a M203 grenade launcher could be mounted. The next evolution in the rail systems was to be the work of A.R.M.S., Inc. Dick Swan. He introduced the free floated rail system on hisRigid Frame System, which would evolve into the A.R.M.S. SIR (Selective Integrated Rail) system. This solved several issues Swan saw of the original systems. No tension was on the barrel with the use of vertical pistol grips, no heat transferred from the front sight assembly back into the forged aluminum receiver and it increased the thermal threshold of the barrel. Sights stayed in alignment due to the barrel not contracting and expanding with extreme temperatures resulting in accuracy enhancement.

Many companies have since come out with rail systems both free floating and not. Most of the designs were made so an armorer in the field could install them. No modifications were made to the weapon. Others, well, lets just say it would take an entire gunsmith shop to install.

VLTOR, to compete in the market, designed their own free-floated rail system called the CASV-EL (Extended Length). This system is made completely of aluminum with the exception of the stainless steel mounting hardware. The CASV was designed for the U.S. Navy E.O.D. Groups (Explosive Ordnance Disposal). It consistsof a full length top rail that puts a “protective sleeve” over the rail on the M4 upper receiver and attaches to the barrel nut. Different length Mil-Std-1913 rails are provided with the system and may be screwed into the desired location on the rail system.

Installation is extremely simple. The CASV-EL used for test and evaluations was completely installed in less than 5 minutes on a Colt LE6921 carbine. Remove the standard M4 handguards. Prior to installation the side mounted sling swivel had to be removed from the barrel of the carbine. Remove the lower handguard from the CASV, pull backward on the delta ring on the upper receiver of the M4. Insert the rear of the CASV into the barrel nut (it interfaces with the scallops on the barrel nut). Install the mounting clamp and screws. That is all there is to it. The largest benefit to this design is that there are no modifications to the weapon. Some other manufactures require the front sight assembly to be removed as the flash suppresor.


Even with so much effort going into trying to change operating systems and find replacement weapons, the M16/M4 is here to stay. This is why so many manufacturers are designing and marketing all these new gadgets to enhance the modularity and versatility built into the family of weapons. VLTOR is definitely onto something. Their equipment has proven itself and the VIS has great potential for giving the endusers a lightweight package capable of multi-calibers using standard barrels. VLTOR has gone to great lengths to keep as much parts commonality and interchangeability to the standard M16/M4 possible. Their Modstocks and CASV fit with no modifications to the firearm. This is a sure plus.

VLTOR Weapons Systems
Phone: (520) 408-1944
Fax: (520) 293-8807
Web: www.vltor.com

This article first appeared in Small Arms Review V10N11 (August 2007)
and was posted online on November 23, 2012


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