Just a in the manner of Mauser rifles, the LE # 4 and #5 extractor will engage and lock itself into the rim of the cartridge, as the bolt is pushed forward from the rear, towards the chamber.
I will agree, that the LE # 4 and # 5 have the added advantage over the Mauser, that it also can, without the risk of breaking the extractor claw, have a single round loaded into the chamber, and the extractor slipping over it.