Dont forgot about military weapons used for avalanche control
"Military weapons were first used to control avalanches in North America in 1949 at Alta Ski Area, Utah and Berthoud Pass, Colorado. Military weapons proved remarkably successful and use quickly expanded; today, thirteen Forest Service permitted ski areas, five state departments of transportation, one state owned railroad, the British Colombia Department of Highways, Parks Canada, and several private operations mostly use 75mm and 105mm recoilless rifles for avalanche control. Many of these users literally depend upon 75mm and 105mm recoilless rifles, last manufactured in the late 1940 's and early 1950's, for public safety and economic viability; unfortunately, only about a five year supply of these weapons and ordnance exist."
http://arc.lib.montana.edu/snow-scie...90-167-174.pdf