CZ 550 .243 Winchester
The CZ 550 system consists of a receiver that serves as the systems shroud and a bolt group of which the bolt body has three locking lugs, two large main lugs at the bolt head and a third safety lug underneath the bolt handle acting as a backup. The bolt handle is permanently attached to the bolt and is turned-down and backwards for use with optical sights.
Another distinctive feature of the CZ 550 system is the controlled-feed mechanism, consisting of a large, non-rotating claw extractor that engages the cartridge case rim as soon as the round leaves the magazine and firmly holds the cartridge case until the round is ejected by the ejector, mounted inside the receiver. The CZ 550 bolt action will cycle correctly irrespective of the way the rifle is moved or positioned during the bolt cycling action or if the cartridge has been fired or not. Only if the bolt is not brought back far enough, sharply enough, in a controlled round feed bolt action the cartridge case may not be cleanly ejected and a jam may result.
The bolt houses the firing pin mechanism that visually and tactilely protrudes from the rear of the bolt indicating if the action is cocked or not. A small disassembly button offers the possibility to access the firing pin and spring.
The action features a large gas relief hole at the bolt body designed to protect the user’s head in case of a primer or cartridge rupture or detonation. When the action suffers a catastrophic failure it is designed to deflect the debris away from the operator’s face.
The CZ 550 bolt group can be easily removed from the receiver simply by pushing the disassembly button, located at the left wall of the receiver, and then by rotating and pulling the bolt out.