hi-cap

A high-capacity magazine (or large-capacity magazine) is a firearm magazine capable of holding more than the standard number of rounds provided by the designer, or legally, a particular number of cartridges dependent on jurisdiction and kind of firearm. Typically high capacity magazines can deliver more rounds through a number of designs – drum magazines, extended box magazines or extended double stack magazines.
For legal purposes, in some jurisdictions magazines holding more than 10 rounds are considered "high-capacity." This can be problematic as typical magazine capacity is between 15 and 18 rounds for popular modern semi-automatic pistols, or up to 30 rounds for modern sporting rifles.

View More On Wikipedia.org