Each one has its uses.
gray, brown, green, yellow
No such thing. You can have small caliber but not low caliber.
If you are reffering to speed, there is no calliber that can beet the .177. You can get a .177 gun that shoots anywhere from 150 FPS to 1200 FPS. There is a catch though, because energy is calculated by mass X exelleration, you can learn that where the .177 has high speed, it has very low mass. If you got a .20, .22, or .25 calliber gun, than you would have very low speed but very high mass.
high
Not sure where Hilti starts their lowest level, so I will start at the absolute lowest. From low to high, grey, brown, green, yellow,red. I think they start at brown.
Usually low resistance is better.
Low rise are better
low burn your hair with high
Low hz
Not firearms related.
What is better a high lift lawn mower blade or a low lift blade.
Depends on the gun. As low as $50, as high as $50,000. Most are between $150 and $600.