H&K Underwater Pistol P11

[Robert Scott]

I had never heard of this before. 30 to 45 foot underwater range.

Pretty cool but you gotta send it back to the factory after you have fired all of your 5 (five) rounds...
Just tell the bad guy you're trying to kill you'll be back in a couple of weeks to finish him off...

https://special-ops.org/heckler-and-koch-p11-underwater-pistol/

[barretcreek]

Recall seeing a Gyrojet pistol in the '60s at a gun shop in Silver Spring MD.

https://en.wikipedia.org/wiki/Gyrojet

At least it could be reloaded right away.