Mauser actions use a controlled round feed, meaning that the bolt grips the cartridge as it loads it into the chamber. Most modern rifles, like Remington, and Browning use a push feed action where, as the name implies, it simply pushes the cartridge into the chamber. The Winchester Model 70 currently comes with a Mauser action.
The idea behind controlled round feed is that the cartridge remains in complete control during the loading process and it is never loose in the reciever. It was designed for battle rifles subject to violent movements and unorthodox shooting positions. A controlled-round feed type action will feed correctly with the rifle held at any angle and even upside down.
Controlled-round feed designs also prevent double feeds. This is because when the extractor has captured one cartridge, a second cannot leave the magazine without the first being ejected. Either way, only one cartridge makes it into the chamber.
Full length, Mauser type extractors not only increase feeding reliability, but they take a bigger bite on the rim of the fired case, making the extraction of dirty or oversize cases, or those affected by pressure due to high ambient temperatures, more certain. Most other designs do not take as positive a grip on the case rim as a Mauser claw extractor, making failures to extract more likely.
Winchester stirred up a lot of controversy when they got rid of their controlled feed action in the Model 70 in 1964 (hence M70 "pre 64") which led to some pretty strong opinions from consumers.
With a push-feed action design, incorrect operation (particularly “double stroking” the bolt) can result in two cartridges trying to enter the chamber at once, jamming the rifle with potentially catastrophic results for the hunter of dangerous game. However this is a very rare occurrence.