Magnum Force

Magnum Force increases damage of secondary weapons at the cost of reduced accuracy by 6% and -3% per rank, at a maximum of 66% and -33% at rank 10, respectively.

Tips

 * This mod is effective when combined with Lethal Torrent and Barrel Diffusion on 'spray and pray' type Pistols against a wide array of enemies.
 * Targeting Subsystem can almost completely negate the accuracy penalty from this mod once its effects activate, down to a 3% reduction of accuracy when combined with a fully-ranked Magnum Force. Keep in mind however that the accuracy bonus from Targeting Subsystem will only take effect once you hit an enemy and will only apply when you're aiming.
 * This mod is generally inefficient, with an extremely low damage bonus compared to Hornet Strike, an accuracy reduction, and a prohibitively high cost both to level and to equip.  It is currently considered totally inferior to elemental mods and faction mods for raw damage output.
 * The Angstrum can benefit from this by allowing its charged shots to cover a larger area at the cost of limiting long-range capabilities.

Trivia

 * When it was first released, Magnum Force increased recoil as well as damage. However the recoil penalty did not affect recoil-less weapons (Acrid, and Embolist, among others). This was confirmed to be unintentional in Warframe Prime Time - Episode 2 (9:40). The mod's effects were changed Update 10.4 to give weapons an accuracy penalty instead of a recoil penalty.
 * "Magnum Force" is the name of the second movie in the "Dirty Harry" series of films starring Clint Eastwood.