In actuality (and in physical theory) velocity and momentum are inter-related.

As hunters, we like to talk about penetration, but in physicality it equals momentum.

By switching to a load with the same size shot and lower velocity, you in theory will actually be decreasing momentum.

Hence, that' s why 4' s carry greater knockdown power than 6' s, because the tradeoff in the larger shotsize (momentum basically equally mass X velocity) outweighs the small loss in velocity.

However, a size 6 shot load with more pellets and less velocity will equal less momentum...just with more BB' s not penetrating. The mass in this sense is the mass of each individual pellet, not the entire mass of the load.

To think of this in easier terms, if you pick up some steel bearings and throw them with either your arm or a slingshot, which one penetrates better. The answer is obvious, the shot being propelled via the weapon applying more force and more velocity.

If you' re worried about penetration past 40 yards, try shooting HiV 4 or 5 shot. That' s why 5 shot has become so popular in the last 5 years, to offshoot the velocity/penetration conundrum between 4 & 6 shot. Basically, a happy medium[