This loader doesn't work with the Armalite AR-10 that doesn't have a rear catch on the magazine.  It will work on AR-10 magazines with the rear catch.

Magazine loader & unloader

(US Patent 6,810,616, Canadian pat. no. 2,416,448)

The LULA™ loader & unloader is a military-quality personal magazine loader and unloader. It facilitates both loading of loose rounds into a magazine and unloading them out of the magazine. It does so fast, safely, comfortably and painlessly. Usable for tens-of-thousands rounds.