A guy I went to high school with was on a cutter down in the islands somewhere and told me a story of fighting it out with a drug runner boat, they were shooting up at the Coasties on deck with small arms but were well under the minimum elevation of the cutter's deck gun.
The Coasties turned the drug boat into a colander with .50 caliber MGs when they saw the drug guys uncovering out a WW2-era 20MM Oerlikon gun. Wish I knew where he was today so I could ask for the specifics on where he was at the time. This would have been in the late 80s or early 90s.