Full power 00 buck, 9 pellet is the standard. They penetrate >18" up close and pattern tightly, making a good intermediate range load. My 12 guage with a mod choke will keep 7/9 on a 8.5x11 paper at 25 yards, and the farther the range, the lower the velocity, and the lower the velocity the lower the penetration. All these factors add up to 00 buck being less than ideal for "up close and personal," and a great load for 15-35 yards, approximately.

Personally, I like more, smaller pellets for a shotgun, and lighter loads, so I found 20 gauge was a perfect fit for me. 20 pellets of .25 caliber that penetrate 12" of gelatin in up close tests seems perfect in my opinion.