PVAR rifle

The Pneumatic Valve and Rod rifle also known as UDMC PVAR rifle is Filipino assault rifle, manufactured by United Defense Manufacturing Corporation, and is a variant of the Armalite AR-15 and M16 rifle.

The rifle uses the Pneumatic Valve and Rod system, which was created as a more reliable design than the traditional direct gas impingement system of the AR-15 family.

History
United Defense Manufacturing Corporation undertook the development of the rifle as a possible replacement for traditional AR-15 designs which utilize a direct gas impingement system.

Design
Problems of the traditional Direct Gas Impingement system was of its extreme heat and carbon deposits in the bolt assembly and bolt carrier group. The problem occurs during the firing of a round and in order to recycle the weapon’s mechanisms, necessary force through high-pressured hot gases from the barrel’s gas port, are rammed back through a gas tube to the bolt assembly and bolt carrier group. As a result, wear and tear after a few thousand rounds become evident. Another problem was that of xcessive recoil and muzzle rise are due mainly to the conventional high-powered rifle’s high operating cyclic rate of fire (approximately 850-950 rounds per minute) and to the design itself whereby the hot compressed gases are rammed back into the bolt contributing to the recoil and muzzle rise. This results to cycling and reliability problems and firing accuracy issues. Simply put, due to its higher rate of fire and overall design, the rifle has a high tendency to jam and the soldier will have trouble controlling his aim when the rifle is fired on bursts or full automatic due to too much recoil and muzzle rise and flip to the “1 or 2 o’clock” position.

This problems were fixed by the PVAR rifle's system. Where in the Direct Gas Impingement System pressurized gas is used throughout the operating cycle, the UDMC PVAR System utilizes instead mechanical energy for a more effective and more reliable cycling. The UDMC PVAR System prevents much heat, carbon build-up, unburned powder, and dirt from being deposited inside the bolt assembly and the bolt carrier group resulting to a cleaner and cooler operation, less downtime for cleaning and repair and, considerably longer life span of the rifle. It can fire underwater and even accept successfully drum magazines.

But this problems are fixed by the cost of a reduced rate of fire from 900 to 750. This is later fixed by attaching beta c-mags instead of standard Stanag mags. The PVAR itself is suited for high ammo magazines because of its ability to fire more bullets in the longest time.