What is Push feed and controlled feed?

Push feed and controlled feed are two main types of mechanisms used in firearms to describe how the bolt drives the cartridge into the chamber and extracts the spent casing after firing.

The better of the two systems has been debated for over 50 years, and both systems have their strengths and weaknesses. Some prefer the controlled round feed for hunting on dangerous game, while others state that either of the systems can be reliable or unreliable, depending for example on the quality of the rifle and maintenance. There has been a trend that newer rifle models tend to have a push feed mechanism, while almost every modern semi-auto pistol has a controlled round feed. A push feed system is in most cases cheaper to manufacture.