To get the most performance and highest ballistic coefficient possible out of the chosen cartridge, long range competitive shooters often handload ammunition with the longest, heaviest VLD (very low drag) projectiles available. The result is often a loaded round of ammunition that is too long to fit the envelope of the AR-15 magazine. The Bob Sled fixes this problem by locking into an AR15 magazine well like a standard magazine, and providing a shallow trough onto which an extra long cartridge can be placed and held in perfect alignment with the chamber for smooth loading. The Bob Sled incorporates a plunger which locks the AR-15's bolt open after each shot, allowing the process to be repeated. Constructed of Delrin for durability, the Bob Sled is sized to match the profile of a regular 10- or 20-round magazine, and is also available for the AR-10.