I knew a couple guys in US Navy helicopter sear and rescue (SAR) that packed privately owned Magnums: an M19 and an M28, both in 4" and in armpit holsters. Ammo was no problem, as it was readily available at the PX. Navy regulations required carrying only .38 Special ball-tracer cartridges, but these wiseguys always packed Winchester-Western or Super Vel hollow points. The Navy designated the sidearms function as primarily emergency signaling, with personal protection as a last-ditch effort. Ball M41 was also available, but seldom issued to aircrew.