Before I reply, let me give you my experience. I'm a retired Police Sgt. that was FBI trained and certified firearms instructor, SWAT, and sniper. Over penetration was always a concern for me and I'm sure for most LEOs. Like one person said, shot placement is very important. So practice as much as possible. I'm in agreement that slow big bore rounds are the way to go. The reverse hollow base WC was a trick that was used a long time ago and I still believe in it today, especially in an environment that you described. I would stay away from fragmenting bullets. In church I carry a .45acp, or a .44 sp, or an S&W model 25 in .45 Colt. They are all slow moving big bore rounds that take some of the concern off about over penetration. They are carried in an iwb under my jacket. I would stay far away from + P ammo for fear of over penetration.