Some guns yes, but most guns would require gunsmithing to change caliber.
The standard caliber of a biathlon rifle is .22.
a .22 caliber
A .177 caliber air rifle has very little recoil.
Rifles can be rechambered, if the rounds are the same caliber. You'd do this to change cartridges of the same caliber. Rifles can also be rebarreled. You'd do this to change calibers and cartridges. You can also replace the action in a rifle to change the action length. The cost of rebarreling(new caliber and cartridge) and replacing the action(new action length) would be prohibitive. It would be cheaper and easier to sell the 308 and buy a 338 magnum.
.223 caliber or 5.56mm.
No You could build a rifle in .306" or any other caliber but you are likely referring to 30.06. A 30.06 rifle is referred to as "30 Caliber" but to be accurate it is nominally .308"
Yes, I can. A Barrett M107 is a .50 caliber sniper rifle.
The Dragunov (note corrected spelling) sniper rifle is in caliber 7.62x54mmR. This is the same caliber at the Moisin-Nagant 91/30 rifle.
50 caliber
value of a model 49 ithaca 22 caliber rifle
You will need the services of a good gunsmith.
Depends on the application. If you mean power, the higher the caliber, the more powerful it is. for example, a .22 caliber rifle is much less powerful than a .50 caliber rifle.