Blue Book of Gun Values
Do a google search on continential rifles or multi barrel rifle systems.
Local stores that sell guns or weapons will have a variety of information for an consumer with questions about sniper rifles. Academy and Wal-Mart are two different providers of guns and weapons who also sell sniper rifles.
Maybe in Canada
Owners manual, Gunshop, most rifles have the caliber listed right on the barrel
try: SAVAGE SHOTGUN.COM
Blue Book of Gun Values has some information.
Library, internet forums, internet searches
No way to answer with just the information given. Who made it?
10-100 USD or so
You are aware that Ruger has made .22 caliber rifles, pistols and revolvers? You have to give information to get information.
The Greener bullet was for muzzleloading rifles- although it COULD be used in a single shot, muzzleloading pistol. See the link below for a little information.
Any good sized library will have books on firearms and how they work.