Thread: M70 bolt stuck
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Old November 4, 2012, 10:24 PM   #9
James K
Join Date: March 17, 1999
Posts: 24,160
There is a fari amount of misunderstanding of the reason for "controlled round feeding". The usual statement is that it allows the rifle to be loaded under combat conditions where the rifle might be in a position other than perfectly upright. That is true. But the real concern in the early days was a bit different, and didn't show up until the advent of pointed jacketed bullets.

In a push-feed rifle, if a round is chambered and the bolt is not comletely closed due to haste or error, if the bolt is then pulled back to chamber another round, when the second round is pushed forward, its pointed jacketed bullet can be jammed into the primer of the chambered round, with interesting results. With CRF, the extractor grips the rim of the case as it is pushed out of the magazine; if the round is chambered without the bolt being locked and the bolt is then opened, the cartridge will be pulled out and ejected.

The designers of push feed rifles recognize the problem, but design the feed rails and ramp to keep the bullet point away from the primer of a chambered round, plus the use of soft point sporting ammo and the lack of a need for rapid fire combine to mitigate the potential problem. Push feed rifles, having no need for a large extractor cut, can be designed to handle very high pressures. So the designers chose to accept some of the known problems of push feed so they could make rifles that powder happy reloaders wouldn't blow up.

Jim K
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