I prefer 12 gauge 1 1/4 of 5 or 6 shot with the heaviest dram of powder. However I always like a fast load over a heavy load. If you will be doing lots of walking behind dogs nothing beats a 20 gauge with 3" inch loads of 1 1/8 oz of #6 shot. If you walking a lot I always say go with as light as gun as possible that way you will be quicker when the time comes to pull the trigger.