I don't know much about guns, only shot a couple in my life, all .22's or 12-guages. I'm looking for a hunting rifle and have read here about the best calibers, etc. A family member recommended a .300 WSM. What I'm wondering is - If I buy a rifle chambered for that, how many choices do I have for ammunition? Do I have to get only .300 WSM, or can I shoot all the other bullets that have the same .308-in cross section, like 30-06, .308, .30? If not, are there any other cartridges I could use at all?