What’s the difference between a ‘push feed’ and a ‘controlled feed’?
- Credit: Archant
Can you explain the difference between a ‘push feed’ and a ‘controlled feed’ bolt-face on a rifle action? Chris Parkin replies
Q: Can you please explain the difference between a ‘push’ feed and a ‘controlled’ feed bolt-face on a rifle action?
CHRIS PARKIN replies: Most modern rifle designs use a push feed bolt-face like a Tikka or Remington, where the circumference of the otherwise slightly recessed bolt-face nudges the brass cartridge forwards and out of the magazine, up the feed ramp and into the chamber. As the cartridge pushes into the chamber, finally coming to a halt as its shoulders meet those within the chamber, the bolt drives over the case’s head and the sprung-loaded extractor claw, or internal circlip, is forced open, and then clips back over the case’s rim as the bolt is closed. This is a somewhat comparatively aggressive process but works with brutal simplicity and allows rounds to be literally thrown onto the magazine follower or into the chamber, and the bolt-face forced closed over them.
In contrast, a controlled feed bolt-face like that of the legendary Mauser 98, or its hereditary peers such as CZ 527 or Ruger 77, allows the magazine’s follower to slide up the rim of the cartridge case – behind the extractor claw on the bolt-face at its fully rearward position – before it slides forwards in the magazine and up the feed ramp into the chamber. Because the rim is already under the extractor claw, this process can feel a little gentler, although the rounds nearly always only work when magazine fed, rather than single loaded. The usually far sturdier full-length extractor claw won’t easily clip over the rim of the case when it is in ‘battery’, so to speak.
Both systems have benefits but I find the controlled feed more likely to fall foul of case rim thickness variation in the brass, especially on actions such as the Sako 85’s, which combines elements of both designs. On the other hand, modern rimmed cases, such as the .17 Hornet, benefit from the gentler control of the 527 action in my opinion – it holds them onto the bolt-face and directs the tiny meplat of the bullet straight into the chamber, rather than scraping its delicate bullet up a feed ramp on what is a thin-necked case. Combined with a recessed rim to the chamber, which can easily snag the tiny bullet’s meplat, ‘controlled’ is far better.