The G3, as you may know, is a semi-automatic rifle that utilizes a roller-delayed blowback system of operation. In general, blowback refers to any action that operates on the energy created by the movement of the cartridge as it is forced back into the bolt head by the expansion of gases that result from combustion in the chamber. In any firearm that employs roller-delayed blowback, the locking rollers are an integral component of the bolt. Locking rollers are small, cylindrical parts that serve to both hold the bolt in battery and release the bolt from battery.
The G3 bolt locking rollers are original parts manufactured by Heckler & Koch. They are housed in the locking roller retainer plate and located in the breech. As in any roller-delayed blowback operated firearm, the barrel is fixed. When the bolt head is forced back, the bolt locking rollers move inward against the bolt carrier extension, forcing it back at a high velocity and delaying movement of the bolt head. If either of the rollers fails, it will need to be replaced immediately.
For a better grasp on the rollers and where they are located, check out this overhead schematic of the G3’s roller-delayed blowback device. For $3.95, you will receive a replacement pair (two) of G3 bolt locking rollers.
G3 Bolt Locking Rollers 2-pack
The G3 bolt locking rollers are a component of the roller-delayed blowback device and located in the breech. They are original factory parts made in Germany by HK.
Spare parts are an important consideration when it comes to firearms. Like any machine, firearms rely on a series of parts to function properly, including any component of the bolt. If a part breaks or fails, a repair or replacement is necessary.
It is also important to consider availability. At this time, Keepshooting.com has a wealth of authentic, original factory parts from HK for the G3/HK91/PTR91. Not only are they readily available, but also they are cheap. Now is the time to take advantage.