VIS (Versatile Interface Structure)
One of the most innovative products available from Vltor is the Versatile Interface Structure (VIS) upper receiver assembly. After 12 years of concept, development and testing, the VIS integrated receiver and rail platform is now available.
The VIS is a polylithic upper receiver assembly that ties the normally individual receiver and handguard into an aggregate single part. This combination overcomes many problems that are associated with the traditional "two piece" design, most notably being greatly improved structural strength and repeatable accuracy; while affording the user the benefits of a free-floating barrel and rock solid railed fore end.
Installation and legal note: The installation and the assembly of the VIS kit should be performed by a qualified gunsmith and/or certified armorer. Each kit comes with a barrel nut installation spanner wrench.
Background and Additional Information
The VIS features four properly dimensioned Mil-Std-1913 Picatinny rails: The top rail is one continuous rail from the back of the receiver section, to the front of the VIS; the two side rails extend from the front portion of the receiver section, to the front of the VIS; and the bottom rail is attached to a removable lower section of the handguard portion. This removable lower section allows for the attachment of the M-203 grenade launcher, as well as assists in cleaning and maintenance.
The manufacturing process of the VIS is unique...starting with what is essentially a traditional separate upper receiver and handguard, these parts are partially machined then permanently joined using an exclusive welding process - this composite unit is then stress relieved, final machined and heat treated. This innovative process allows the VIS to accept any standard AR barrel! The only thing that is changed is the barrel nut used with the VIS, the required barrel nut and wrench is included with each VIS kit.
Another Vltor exclusive is the modular shell deflector and bolt assist assembly. The VIS gives the operator the opportunity to choose between a shell deflector/bolt assist combo or a shell deflector only.
While the VIS is not the first one piece upper receiver for the AR-15/M16 family, it is the first design that retains the use of standard barrels, as well as a removable bottom rail section that allows the mounting of the M-203 grenade launcher and all SOPMOD components.
Due to popular demand, Vltor also offers the unique receiver section of the VIS as a standalone Modular Upper Receiver (MUR). The MUR is a direct replacement for the MilSpec AR-15/M16 upper receiver that offers exact dimensions and tolerances, improved strength and unique modular design.