BPA---There is no substitute, in shotgunning anyway, for proper gun fit. Your eye is your rear sight in shotgunning, so you need a gun which fits YOU. You must handle as many 20 gauge guns as you can so that you can get a comparative feel for what fits you best. Consider length of pull (the distance from the middle of the trigger to the middle of the butt)--if that length is too LONG, you won't be able to shoulder it quickly, you'll not be ble to get your head down on the gun and see a proper sight picture.. If too short, your thumb could be hitting you in the nose when you fire.
Also, consider the weight of the gun. If too light, it's hard to keep the gun moving ahead of a crossing target. And, a very light gun subjects you to more recoil than necessary. If too heavy, it's harder to carry all day and still be ready for that magical, end-of-day, last hour when the shooting often is best.
Gun fit is an extremely subjective thing! Due to differences in build, body strength, recoil tolerance, etc. what works for me could be a non-starter for you. Wind River has a point--no one but YOU can tell you how a certain gun feels.
In terms of testing guns, you might go to a skeet or sporting clays range--preferably with a friend who knows his way around, and look at/handle (ASK PERMISSION FIRST!) several different guns there. Or if you have buddies who shoot, ask to handle their guns to check how they fit you.
Before you lay out big money for a new 20 gauge, have an idea of how the different guns feel in your hands. Careful you don't step in the bullshit offered by various gun shop clerks, many of whom don't shot a lot and just repeat what they hear clients say. CAVEAT EMPTOR--and good luck--the "hunt" for a new shotgun can be exciting and fun.
