I occasionally read shtuff about magnums just having more pellets than regular shells. And its as though its a given and everyone understands it. But its simply not true. If shooting didn't convince you maybe a little physics will. I'll use some data from Federal's Powershock #00 Buck rounds.
First some common sense. If I throw nine bricks at you at a given speed they have a certain amount of energy in them. Right? If, instead of nine I throw 15 at almost the same speed, isn't it obvious there's a lot more energy there? Yup, I have to work alot harder to throw 15 instead of nine. Let's see if its worth it...
Energy = 1/2 mass times velocity squared
or
E = 0.5mv*v
00 Buck equals 53.8 grs. per pellet.
A standard 2.75" Buckshot load has nine pellets (1.11 ozs. total weight) and they have a velocity of 1325 fps from the muzzle.
.5 x (53.8 x 9) x (1325 x 1325) = 425,036,813
A 3" Buckshot load has 15 pellets (1.84 ozs.) and they fly at 1210 fps.
.5 x (53.8 x 15) x (1210 x 1210) = 590,764,350
590,764,350 / 425,036,813 = 139
This demonstrates that the 3" Mag has 39% more energy in this particular example of Federal 3" magnum ammo over their regular load. I have not translated these into foot-pounds of energy. Federal's Powershot 2.75" "magnum," which has 12 pellets at 1290 fps, has 26% more energy. Intuitively this makes some sense...
33% more pellets, 33% more weight (1.48 ozs.) only they are going a little slower so not quite 1/3rd additional energy. The 15 pellet, 1425 fps, 3 1/2" Win. magnum load mentioned in an earlier post is 100% more, or twice as, powerful as a standard load -- on a personal note I'm never shooting one of those. You may have realized that a little velocity goes a long way, energy-wise. That's why we can never go faster than the speed of light, but that's a subject for another day and forum...
It is ultimately energy on target that stops it. Just counting pellets is not particulalrly useful, at least not without an understanding of the energy involved; in fact it is a red herring! It also helps to understand the performance of shot at various ranges and upon targets.
Ever hear that for every action there is an opoosite and equal re-action? Don't you feel more recoil from a magnum!? You'd have to deal with that which I wouldn't typically recommend, but regardless, they are actually more powerful.
I am a proponent of Buckshot smaller than 00 Buck by the way.
Al