While AR has seen some versatile guns from Pentagon programs that are easier to maintain and are more reliable, the 21st century has offered modular rifles that are giving AR a run for its money. Some of the best tactical rifles right now come from the FN’s SCAR series which include the 5.56mm NATO Mk 16, 7.62mm NATO Mk17, and Mk 20, all of which use a short-stroke gas system. Another rifle called the Masada developed by Magpul also uses short-stroke gas pistons as well as a rotating bolt, but variants of the Adaptive Combat Rifle tend to run for less. The Italian army uses the Beretta ARX series which include the semi-auto ARX-100 now on the consumer market. The Czech Republic uses the BREN 2 multicaliber rifle, the German army uses a 5.56mm NATO G36 carbine designed by Heckler and Koch, and the Poland Army is currently developing the Modulowego Systemu Broni Strzeleckiej GROT.