Our team uses the Lyle (Bridger) line gun. A brief history of the Lyle (Bridger) line gun can be seen here: http://www.cannon-mania.com/lyleguns.htm
The model we have can be seen at these two web sites:
http://www.lhrservices.com/search_and_rescue/line_gun_kit.htm and
http://www.rocknrescue.com/acatalog/Line_Throwing.html

We did have to get some type of exemption/license from BTF, since the barrel is shortened.

We are also in the process of buying the Sherril Big Shot also shown on the second web page. Pete