ADCOR BEAR 5.56x45mm

The Adcor BEAR was designed for the purpose of upgrading…

The Adcor BEAR was designed for the purpose of upgrading the basic infantry weapon. The BEAR—shown here with a SureFire M900V vertical foregrip and Trijicon ACOG—surpasses a conventional operating system by utilizing a unique gas/piston hybrid that builds on the strengths of each system.

At first glance the Adcor Defense Brown Enhanced Automatic Rifle (BEAR) look likes a standard AR-15, but if by second glance its enhanced features have not jumped out at you, then you need your eyes examined. Piston systems are fine and good, but the BEAR is designed to compete in a future military rifle improvement program, the BEAR is not a conventional piston system—it is a hybrid.

The BEAR system takes the best of a variety of the other systems and builds on their strengths. It a modified AR-15 bolt carrier, with the most noticeable difference being a long rod attached in place of gas key. The appearance of the BEAR is reminiscent of the AK-47 bolt group. The end of the bolt rod fits into a short tappet near the muzzle of the rifle that receives the force of the exhaust gases. The tappet is propelled back sharply for a very short distance, and this movement pushes the bolt rod backwards allowing the bolt to unlock and recoil under the kinetic energy of the discharging cartridge. All of the hot exhaust gases stay in the front of the system and out of the receiver, which is the big benefit of a piston system. The BEAR overcomes the adverse mechanical influence of the piston slap and subsequent carrier tilt by using the length of the bolt rod as a mechanical guide, thus keeping the bolt from from wobbling around inside the receiver. At its core, the system is a “short-stroke” piston rather than the short-stroke system more commonly seen in AR piston variants today.

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BEAR’s bolt carrier and key design requires two pieces—carrier and piston key—as it would be impractical to manufacture the bolt carrier and long piston rod as single piece.

The bolt carrier and key are is made by Adcor. The BEAR design requires two pieces—carrier and piston key—as it would be impractical to manufacture the bolt carrier and long piston rod as single piece. With more common short-stroke piston systems, the bolt carrier and key are one-piece. This design is touted to be as superior to the Mil-Spec carrier, where the key is screwed onto the carrier from the top and then the screws are Loctite and pinned to prevent them from backing out. In the world of do-it-yourself kit-built ARs, there are concerns that if the bolt carrier is of inferior production the screws can back out, which may cause the weapon to jam very soundly. This is generally not an issue with factory-built rifles like the BEAR, where assembly jigs and precision tools are used.

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The dustcover is slightly modified to function with the BEAR wiper system, which is fitted with springs that push the wiper outwards and fill the ejection port, effectively sealing it to significantly reduce the infiltration of debris.

The gas system can be adjusted by turning the regulator valve located in the forward part of the gas block. The gas regulator value is available with either two or four positions of adjustment. The four-position valve is more military oriented. It can be opened or closed down for suppressors or running a very dirty weapon. The in-between positions are for best function depending on ammunition type.

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