Steyr Arms and Glock have stepped forward with legal challenges against Sig Sauer Inc, the winner of the U.S Army’s Modular Handgun System competition. Despite attempts to slow down the adoption of the Sig Sauer M17, the Army hasn’t lost momentum in its mission to upgrade to a more modern pistol. Steyr Arms Inc. filed a lawsuit against Sig Sauer on May 3, claiming the interchangeable trigger group contained by a polymer housing infringes on its patented design.