cpa:
The energy/work applied to ounce of shot to accelerate it from 0 to 1200 fps is the same whether it is applied in a 12 gauge or a 28 gauge. There may be minor differences in the efficiency of the energy used to apply that energy to the shot charge but they are most certainly very small.
The shot at the bottom of that 28 gauge shot column will experience more stress than that shot at the bottom of the 12 gauge shot column. Thus the 28 gauge shot is more likely to be deformed.
There are tables that show how long it takes a given size shot to travel a given distance, based on a particular muzzle velocity.
It seems that it is the nature of most firearms enthusiasts to always strive to increase the effective range of their chosen weapon. Over the last 150 years, in pursuit of that goal, choking was developed. Then progressive powders allowed an even larger charge of shot in the same gauge. Shot cups and pie crimping were developed with the aim of getting more effective range from a given shot charge and muzzle velocity.
So if I don't have any "fliers" losing velocity and drifting out of the pattern before they arrive at the target I have more pattern density. Given the correct choke I now have extended my range.
#9 shot runs out of penetrating power before it runs out of pattern density. #4 shot runs out of pattern density before it runs out of penetrating power.
Shot stringing lowers pattern density at the target and thus the maximum effective effective range for a given combination of shot weight, muzzle velocity, and choke. If you don't think so imagine a shot string fifty yards long.
If you load one ounce of hard 5% antimony shot into a modern plastic shotcup in a shot shell and then optimize the choke selection you can get a longer effective range than if you pour 1 ounce of the same size soft lead shot onto a fiber wadded shot shell and then put a shotcard on top of that and roll crimp it. Again with an optimally selected choke.
I shoot mostly trap and bobwhites (over pointing dogs). I am not worried about shot stringing or extending range. But I find the theory and the experiments and the discussions and articles about it very interesting and follow them closely. I shoot competitive trap but I don't win, place, or show very much. I only shoot 1-1/8oz of #8s with a muzzle velocity of 1145 fps (2-3/4DE). But I buy the cheapest shell I can because I believe, at my skill level, shot stringing isn't responsible for any of my misses. My favorite trap choke is mod.
My favorite load for bobwhites is one ounce of #8s. Again I don't worry about shot stringing. My favorite choke for bobs is cylinder. But I don't worry if about the length of the shot column whether I am shooting that one ounce of a 20ga or a 16ga or as 12ga.
But if I was shooting for big money at pigeons or hoping to shoot bunker trap in the Olympics or hoping to win my Regional ATA championship I would pay much attention to shot hardness, bore diameters, and overall shell quality. Because shot stringing affects maximum effective range and quality of patterns.
