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.
.223 caliber or 5.56mm.
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.
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.
No