If 30 yards is max I really would consider a .22lr instead. BUUUUTT I've never tried #4 birdshot, at that range it may be quite effective. At that range you also don't need anything more than a normal full choke. I would look into some of the 'hevi-shot' "X-tended range" or the other heavier-than-lead alloy turkey and/or waterfowl loads.

If you're not going to see 'em before 30 yards you might wanna bring a second set of underwear. If had my first 'scare' last year. That sucker came in fast and was nearly on top of me before he saw me!!!!!!!!!!!! Of course, as luck would have it I was just goofyin' around and didn't have a gun on me. (I was bored, had a mouth call in the truck with me...and figured why not?)