LH Shotguns

Is getting a RH shotgun for a LH shooter a big problem?

I know for bolt the action is on the other side but for most shotguns it's bottom load or break that I've been looking at. Would you consider these ambidextrous?

Yes - I would. Most shotguns and rifles (that don't have a Monte Carlo stock), that are not bolt action - I would consider ambidextrous.

If one shoots with both eyes open it does make a difference. The cast (angle of the butt stock to right or left) changes where the gun sits in front of your sight picture. Regardless of the action type and ejection to right or left, how the gun sits as you aim it makes a difference. As a lefty, my shotgun is cast so that the butt stock "bends" off to the right which then pushes the barrel and sight to the left and more to the front of my face. A neutral cast means tilting my head more to the left, gives a tilted sight picture and less of a natural hold to the gun. Over a round (25 shots) of trap, my lefty will give me on average a 2 hit better result than any of my side by side, over under or pump neutral cast guns. I have one gun with a distinct right hand cast and that's on average 1 hit lower still.

Even shooting rh pump guns is no problem, I find it easier as the eject port is on the right and your front/support hand can quickly load a shell from that side if you need a quick follow up shot while hunting.

Been doing it for over 50 years now. Never had a problem. I do have a left handed pump but never fired it yet nothing to hunt here anymore.