M110A1 may refer to the M110A1 CSASS or the M110A1 SDMR. It is an American semi-automatic sniper rifle that is chambered for the 7.62×51mm NATO round. It is manufactured by Heckler & Koch (H&K) and developed from the company's HK417, and similar to the Bundeswehr G28 configuration. Despite a designation similar to the M110 Semi-Automatic Sniper System, the M110A1 is an unrelated design as the former was a development of the Knight's Armament Company SR-25. The M110A1 CSASS was expected to supplant and eventually replace the M110 in U.S. military service but this does not appear to have occurred as of 2022. However, several thousand M110A1 SDMRs have been fielded with the US Army and Air Force to replace various weapon systems currently being used.