#6 Kent Bismuth. I just ordered a bag of #4 to load after going back and forth between 4s or 5s. When I called to order they were out of 5s so that simplified things! May increase to I 1/8 oz to up the pellet count slightly but we'll see what the patterns are like with 1 oz first. I rarely fire a shot with the 16 at anything farther away than 35 yards but jumping (rough shooting) ducks means they are often heading away rather than a passing shot so I want good penetration. The 4s will definitely give that on ducks and would do in a pinch if I got up close on a goose.