m4oa3 sniper rifle, band scope full metal jacket bullets should kill in one shot to the head
The bore of a gun relates to the diameter of the hole in the barrel - and in turn the diameter of the bullet the gun can fire.
Generally .22 hunting class air rifles good for hunting squirrels. Those that deliver more the 15 ft lbs can be used for hunting rabbits but you should go for head shots. Some air large bore air guns can deliver considerable force good for coyote or even Wild Bore (the Quackenbush Outlaw). The upcoming Crosman Rouge looks like it will be a good varment hunting rifle out to over 100 yard for coyote or smaller creatures. Note Lewis and Clark had an air gun they used to keep meat on their table.
get a bore attachment to a screw gun or drill.
Caliber "Caliber" is a word for the diameter of the bullet or the bore of the gun.
The best brand of .177 caliber gun that is good for hunting will depend upon what type of hunting a person is doing. Two good brands for general hunting are the Daisy and Crossman.
A good handgun for big game hunting would be any manufactures gun in caliber .454 Casull. A good target shooting pistol would be anything chambered in .22 caliber.
What are you asking?
bore diameter
The bore refers to the hole in the gun barrel thru which the projectile (bullet) passes. Some guns have a smooth bore, but many modern guns, both pistols and especially rifles, have a rifled bore, that is, the bore has a helical (spiral) groove that causes the projectile to spin as it flies thru the air. The diameter of the gun's bore determines the size of the bullet or shell (e.g. .22, .45, 9mm, etc.)
Shotgun with buckshot, 30 caliber rifle, etc.
The bore is the inside of the barrel- that is, the hole that the bullet is fired through. The diameter of the bore is measuring how wide the bore is from one side to another.
The range is not directly related to bore diameter. And the largest gun over built (The Tsar bombard) has a 36" bore.