Variable Buffer System

Variable Buffer System #420, #421, #424

The VBS is a Variable Buffer System (VBS) consisting of one to three buffer spacers. Placed behind the bolt, this short strokes the bolt when firing and increases the rate of fire. Each additional VBS spacer increases the rate of fire even more. Do not install more than the indicated quantity of VBS spacers or you will not be able to cock the bolt back far enough to catch the sear.

VBS-1 is a Variable Buffer System consisting of one buffer spacer. When installed in the MAX-31k, the rate of fire can be easily changed from between 660 and 950 RPM. When installed in the MAX-31A mk2, the rate of fire can be changed from between 760 and 840 RPM.

VBS-2 is a Variable Buffer System consisting of two buffer spacers. When installed in the MAX-31 mk2, the rate of fire can be easily changed to 710 or 800 RPM. When installed in the MAX-10/31 mk2, the rate of fire can be easily changed to 610 or 700 RPM. When installed in the MAX-31C, the rate of fire can be easily changed to 699 or 769 RPM. When installed in the MAX-1031K, the rate of fire can be easily changed to 675 or 761 RPM.

VBS-3 is a Variable Buffer System consisting of three buffer spacers. When installed in the MAX-11 mk2, the rate of fire can be easily changed to 690, 770 or 950 RPM. The 690 RPM rate of fire is achieved by installing a single buffer spacer, two buffer spacers achieve a rate of fire of 770 RPM and three increase the rate of fire to 950 RPM. When installed in the MAX-11k, the rate of fire can be changed to 750, 950 or 1140 RPM. The 750 RPM rate of fire is achieved by installing a single buffer spacer, two buffer spacers achieve a rate of fire of 950 RPM and three increase the rate of fire to 1140 RPM. While the VBS was designed with the intention of being used with our MAX-11 mk2 upper receiver, it can also be used with a stock M-11/9, MAX-11S mk2 or MAX-11 Sk to vary the rate of fire.

The rates of fire above are approximate. The rate of fire of your ammunition may vary. Different bullet weights, such as 124 gr. And 147 gr. , as well as lighter or stronger powered ammunition, will result in slower or faster rates of fire.

The VBS easily installs on your bolt assembly by simply installing it between the rubber buffer and the back of the bolt assembly. It is securely held in place with the ejector rod.

VBS Application Cross-Reference:

OEM M-11/9 VBS-3 #420
MAX-11 mk2 VBS-3 #420
MAX-11k VBS-3 #420
MAX-11sk VBS-3 #420
MAX-31 VBS-2 #424
MAX-31k VBS-1 #421
MAX-31A VBS-1 #421
MAX-10/31 VBS-2 #424
MAX-10/31K VBS-2 #424
Single VBS-1 #421

Not available for the MAX-11A1/380, MAX-11A1/9, MAX-10/9 and MAX-10/45 uppers.