GDG- Cannon Fire

[The Mills]

Hello All:

I was wondering if anyone could give some descriptions of cannon fire for the various cannons used at Gettysburg, and here is what I am wondering.  

When I see a cannon demonstration today at the park, they are obviously not using live ammunition and I am wondering how different it really is from a "real" firing of the gun as had been fired during the battle.

For instance:  are they using the same amount of gunpowder (same type, etc), and would the sound / loudness (decibals) be the same between a demonstration today and an actual firing of the cannon?  I assume the cannons wouldn't simply remain stationary, that there would be some sort of recoiling.  How much would the cannon actually recoil?  If they did, would the gun crews then roll them back to their original locations, or just fire them from where they stopped, so in essence, after say 10 - 15 shots, the cannon might be 100 yards from their original deployment?  

Also:  how was it different for a smoothbore Napoleon vs. the rifled cannon?

Any help is appreciated.

Thanks
Andy