“The Protector” was a very discreet palm pistol developed in the late 1800s by a French inventor, produced in bulk by the Ames Sword Company, and sold by the Chicago Firearms Company. They are mechanically double-action turret revolvers with a unique grip design meant to be to be fired by squeezing. The first few were made in France by the original inventor, and later licensed to an Irish-American who sold them through first the Minneapolis Firearms Company and later the Chicago Firearms Company. Most are in an extra-short .32 caliber rimfire cartridge, but a few were also made in both .41 and .22 calibers.
Ian’s Video: [12:57] https://youtu.be/Zv4ekzpWdFk?si=
You actually have it completely backwards. Black powder ammunition heated up gun/rifle barrels much faster than modern powders. The length of time it took for the much more inefficient powder to finish burning off caused the barrels to absorb more heat from each shot.
If you’d like to test this, you can still pretty easily find black powder shotgun loads. Put just 6 shots through one with modern powder and touch the barrel. Then do the same thing after it cools off a bit with 6 rounds of black powder shells. You touch the barrel after that you might want to have some burn cream and bandages on you.