I really don't know much about scopes and what goes on what gun, but i am wondering if the bushnell 3-9x32 would make a good scope for my model 870 rifled shot gun (its got the saddle scope mount) and also on a muzzle loader (which i haven't purchased yet, i'm thinking the knight disc right now though)?

Also how do you tell what scope rings you need? I went and looked at them today and there was hundreds to choose from, i was so confused.

Bushnell makes a scope for shotguns and muzzle loaders. Any scope will work but on Shotguns and muzzle loaders most people want a pretty wide field of view and enough eye relief so the recoil does not bring the scope back and hit your eye brow or your eye. Many scopes do not have enough eye relief. The Simmons Aetec has about the most with five inches. Most Leuplods have four-4 1/2 inches. Bushnell makes one with six inches. The rings you need depend on what you have for bases. (the piece that fastens to the gun.) They will be of the Weaver type where the ring clamps onto the base or the Redfield or Leupold type which turn into the base. I would quess you have the Wearver type. Next would be the size of the rings. Most scopes use a one inch tupee so you will want one inch rings. 22 scopes are often smaller (3/4) inch. There are also some 30MM scope tubes so there are 30MM rings as well. One inch is by far the most common. Then there will be High, Lo, and medium high rings. This is a matter of what you prefer but scopes with big bells on the front may reguire high rings to keep the scope from touching the barrel. It can all be confusing to start with and I am not the best at explaining all of it. A good reputable gun shop can clear it up for you faster in person. I don't know where you live but if you have a Scheels all sports or Cabelas close buy they should be able to help you out. A Bushnell trophy or Banner model should work well for you. Just remember the eye relief part.