Carbine and Rifle Modstock
Revised Date 07/14/2008
Congratulations on your purchase of the VLTOR Modular Firearm Buttstock, (a.k.a. Modstock). We hope you will appreciate the quality of the construction and the versatility the Modstock offers. Please read this Installation and Operation Manual thoroughly before handling the Modstock and/or the contents of the box.

Before attempting installation, please read the warnings and notes first. 

WARNING: The Installation of the any Vltor Modstock System should be preformed by a qualified gunsmith or qualified United States military small arms technician.

LEGAL NOTE: The Vltor Modstock system for AR type rifles can be used on some post-ban (1994 Crime Bill) configured firearms. The only Modstock system allowed on a post-ban (1994 Crime Bill) rifle is the Rifle Modstock and only when mounted to a Rifle Receiver Extension (Colt part# SP61574). The use of a Collapsible Stock Receiver Extension on a post-ban (1994 Crime Bill) rifle is strictly prohibited by federal law (Section 922 of title 18, United States Code). Vltor Weapons System recommends the installer and/or the firearm's owner to check with local, state and federal law before attempting installation/possession of any product manufactured or sold by Vltor Weapon Systems . Vltor Weapon Systems is not responsible for the installation of, use of the Modstock system, or any other related Vltor Weapon Systems product.

A note to qualified installers: Refer to the current United States Military Technical Manuals or Colt factory technical manuals for proper tool needs and technical data, such as, torque specifications. All parts installed during the conversion, including Vltor Modstock components, should be new and certified by Colt and/or the United States Military.

Important Note: The Vltor Modstock System will fit only Colt/military dimensioned, collapsible stock receiver extensions. Other makers' collapsible stock receiver extensions will fit improperly and should be considered unsafe to use. These inferior receiver extensions are not recommended for use with the Modstock system under any circumstances.

AR Rifle Series

Removal of existing buttstock / installation of Modstock for rifle:
Located at the rear upper portion of the butt plate is a slotted screw. With the screw completely removed slide the complete stock assembly off the receiver extension.

Install the rifle Modstock over the receiver extension, making sure the Modstock's forward indexing pin aligns to the indexing hole, located on the back of the rifle's receiver located just below the receiver extension mounting point.

For "A1" length (ARM-1 series) Modstocks:
With the A1 length Modstock installed, insert the Modstock Butt Cap, (supplied with the Modstock kit). Next, with the Butt Cap in place, install the new A1 length Butt Cap Screw (supplied with Modstock kit, known as Colt part #SP62601). Thread and torque screw to proper specification as required in the United States military or Colt factory technical manual.

For "A2" length (ARM-2 series) Modstocks:
With the A2 length Modstock installed, insert the buttstock spacer (found only on A2 versions of the AR rifle series, Colt part #SP64578), followed by the installation of the Modstock Butt Cap, (supplied with the Modstock kit). With the cap in place install a new Butt Cap Screw (found only on A2 versions of the AR rifle series, Colt part #SP64577). Thread and torque screw to proper specification as required in the United States military or Colt factory technical manual. (The Buttstock Spacer, Colt part #SP64578 or the Butt Cap Screw, Colt part #SP64577 are not supplied with the ARM-2 Modstock Kits).

AR Collapsible Stock Carbine Series

Removal of existing collapsible buttstock / installation of collapsible Modstock:
To remove the existing collapsible buttstock, two steps need to be taken simultaneously. Step 1: retract/disengage the lever lock pin. Step 2: slide the stock to the rear of the receiver extension until the stock assembly separates from the receiver extension. To install the new collapsible Modstock assembly, reverse the removal process.

Installation of the Rifle Modstock to the collapsible buttstock receiver extension:
(Before proceeding, refer to Legal Note/Disclaimer at the beginning of the manual.)To remove the existing collapsible stock, refer to the pervious paragraph. Next, install the Rifle Modstock onto and over the collapsible receiver extension. As mentioned before, the AR Modstock will only fit Colt/military dimensioned receiver extensions. The Colt receiver extension (Colt part #SP64072) is available through Colt and/or through a Colt Authorized parts distributor.

When mounting the Rifle Modstock to the collapsible stock receiver extension, two different lengths or positions can be achieved. The first position is the standard position known as "position A". The second position of the stock is an extended length of 0.800 of an inch longer then position A. The extended position is "position B". The Rifle Modstock features two Manual Lock-Pin access ports. Each port allows the stock to be placed in either Position A or B. To lock the Modstock into position A, place the Manual Lock-Pin access port under the receiver extension mating slot. The slots are located beneath and within the collapsible stock receiver extension. The access port for position A is located along the mounting beam near the center of the stock. This port must be indexed to the furthest most stock placement slot of the collapsible stock receiver extension. To achieve position B, the forward access port (found next to the forward sling mounting hole, must be aligned with the closest indexing slot near the firearm's receiver of the collapsible stock receiver extension. This slot would normally be used when the collapsible stock is in the "standard/collapsed" position.

To lock the stock into either position the Manual Lock-Pin must be installed. The Manual Lock-Pin is equipped with every rifle Modstock kit. The Manual Lock-Pin assembly consists of a steel indexing pin and a pivoting composite material latch. To lock the Modstock into position A, install the Manual Lock-Pin into the position A access port, inserting the pin into the receiver extension's slot. With the pin installed, begin to rotate the Manual Lock-Pin, Locking Latch until it contacts the ramping surface (the bridge of material long the mounting beam). Next, by applying pressure to the Locking Latch, the latch will ramp-up and rotate to a complete locking position, simultaneously forcing the Manual Lock-Pin upward in the receiver extension slot. To unlock and remove the Manual Lock-Pin, reverse the installation process.

Installation of Cheek Weld Adapter or Modstock Accessory Compartment:
The installation of the Cheek Weld Adapter and Accessory Compartment are similar. Both items feature locking fingers on the upper portion and mounting flange at the base. Future Modstock accessories may differ in ways of mounting. To install, first plan placement for the chosen accessory, then insert the locking fingers into the square mating holes along Modstock's body. Next, pivot the accessory downward, until the accessory's mounting flange contacts squarely against the surface of the stock. Immediately before the two surfaces contact, the parts will first "snap" together, aiding in it's locked position.

Next, to better secure mounting of accessories, the use of Accessory Mounting Hardware should be used. All Modstock kits come equipped with two Accessory Nuts and two Accessory Mounting Screws. To install, index and insert the Accessory Nut into the accessory and through the Modstock mounting beam. After insertion of the Accessory Nuts install the Accessory Mounting Screw on the opposite side of the Accessory Nut's insertion.

Thread the Accessory Mounting Screw(s) to a snug fit with the aid of a 3/32 hex wrench (which is provided with the Modstock kit). The combination of the Accessory Mounting Screw and Nut will sandwich the accessories and the Modstock together.

Installation of Accessory Compartment Cap:
Every Modstock kit is equipped with two Accessory Compartments (long compartments for the rifle Modstock and short compartments for the collapsible Modstock). Each Accessory Compartment is equipped with two Accessory Compartment Caps. The caps are easy to operate and feature a rotary-lock function. Before cap installation, first make sure the Accessory Compartment is ideally placed on the Modstock, allowing access to either end of the Accessory Compartment. Some users may prefer to block one end of the Accessory Compartment, by mounting close to the backside of the butt plate or near other accessories. If so, first install the cap before mounting the Accessory Compartment.To install a Compartment Cap, place the cap in hand, locate and place the lever downward. At 180-degrees away from the lever there is the access notch (top). Before installation, the notch must index with the locking tooth, found at the 12 O-clock position of the Accessory Compartment. After properly indexing both parts insert the cap. With the cap fully inserted the next step is to rotate the cap into the locked position. There is only one way to rotate the cap to the locked position. To lock, rotate the Compartment Cap lever towards the Modstock's mounting surface. When the cap rotates two functions occur; first, the cap lever detents over the Accessory Compartment support arm, and second, the cap is forced into the compartment bore by means of a camming action. The camming action occurs when the Compartment Cap is forced into the Accessory Compartment with aid from the locking tooth.
Installation tip: Some may find the installation and removal of the caps to be difficult. To aid in the process, apply a dab of petroleum gel or silicon grease to the rubberized material, which seals to the inside of the compartment. The lubricant will also aid in a better seal between cap and compartment.

The operation of the Uncle Mike's Quick Detachable Sling Swivel:
The Vltor Modstock system has the ability to mount a sling, both conventionally and by quick detachable means. To allow the sling to be quick detachable, Vltor has equipped every Modstock kit with one Uncle Mike's Quick Detachable, Sling Swivel. This sling swivel is retained within the stock by means of retractable locking ball bearings. To install the QD sling swivel into the Modstock, first, insert the body of the sling swivel into the Sling Swivel Locking Sleeve located within the Modstock. With the Sling Swivel partial installed complete the insertion by applying pressure to the button. The button is located on the exposed portion of the sling swivel's body. By pressing the button, the locking ball bearings will retract, allowing the total insertion of the sling swivel into the Sling Swivel Locking Sleeve. To remove the QD sling swivel simply reverse the installation process.

The Modstock has multiple mounting points for the Uncle Mikes QD Sling Swivel. For every one Sling Swivel Locking Sleeve molded in a Modstock the Uncle Mike's QD Sling Swivel can mount ambidextrously to either side. For example, the rifle Modstock has two Sling Swivel Locking Sleeves giving the operator the choice of four mounting possibilities. The collapsible Modstock only features one Sling Swivel Locking Sleeve which gives the operator a two sling mounting choices.

Questions?

Modular Firearm Buttstock is Patent Pending.

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Modular Firearm Buttstock - Patent 6925744. Other Vltor patents are pending Copyright 2002 - 2008 VLTOR Weapon Systems All Vltor logos are registered Trademarks.