Patrick, ammo will depend on the task at hand, hunting (bird, deer or hogs, self defense etc). The tighest pattern buck shot is the Federal with Flight Control Wad. Self defense in the home use #4 buck shot which will get the job done without over penetration. Just pattern a few brands to find the ones that pattern best in your shotgun. Cheers and stay safe!

What you can find. It is a pump so you should not need high brass to break it in. After that it depends on what you want to do.