I’m very familiar with bear bangers that you fire from a shotgun, but those are different, they’re actually a large rubber wad that you shoot the bear with, so the bang is the impact the shot makes when it hits the bear. These pen launcher bear bangers get shot in the air, so the bang is the noise from the explosion.
REMEMBER; Bear bangers are there to scare them off before a confrontation, bear spray is for an attack.
Have you ever actually fired a bear banger? There is a moderately loud bang as the banger is ejected from the cartridge, a trail of smoke, and a few seconds later a loud bang as the banger explodes. There is no kickback when the cartridge fires and the cartridge is only slightly warm allowing you to unscrew it and reload right away. Although the pen launcher is a simple device and the cartridges appear innocuous, they are potentially dangerous and have the capacity to damage hearing and to cause burns if used improperly.
Bangers (red cartridge) explode with a loud bang after travelling about 40 m. Whistlers (sometimes called screamers) come in a blue cartridge and project about 80 m. They produce a high-pitched screeching sound for 2-3 seconds until the end of flight. They are said to “… produce an unusual, alarming sound creating an immediate fear reaction in birds and animals.”
So it is unlikely you will use a banger unless the bear is showing signs of aggression and coming toward you. It makes sense to avoid having the banger go off behind the bear as it may drive it toward you. If you fire almost vertically up in the air the banger may technically go off between you and the bear, but so high above the bear that it may run toward you anyway. My inclination would be to aim the pen launcher a little to one side of the bear with a low trajectory so that it goes off fairly close to the bear. If using a whistle, which starts making a noise as soon as it leaves the launcher, I would aim it the same way, but with a higher trajectory. So much for theory. Has anyone used bangers or whistlers in an actual bear encounter?
The best way to deal with bears is to avoid a bear encounter in the first place. Keep you head up, your eyes open and your senses alert when in the backcountry.
Aside from being a lot smaller and lighter (and cheaper), these seem to me like they could potentially be a lot more effective than bear spray, especially considering you could choose to aim the banger at the bear in desperate situations, and it would be effective from a greater range, and could be deployed against more than one bear at a time.