I was shopping for 20 gauge loads and saw 20 gauge (Hevi shot) loads for 3" 1 1/4 oz of shot. One had #5 shot and listed a velocity of 1060 (approx) and the other had 1260 (approx) with #6. Anyone know the reason for the listed difference? The slower load was packaged as turkey loads. The faster one was for waterfowl.