Oleg,
I think you have fallen for a commom misconception that the smaller gauges are "less" than the larger 12 gauge. In fact, the smaller gauges shoot their payload at the same velocities as the larger gauges, they just shoot a smaller payload.
In this case, even the .410 is much more superior than the .22 mag shot shell in both speed and payload.
Don't sell the smaller gauges short, most people do because they have zero experience with them. I both hunt and shoot skeet with the .410 and find that I am not handicapped at all. You just have less shot to do the same job so you have to be extremely percise. After shooting a 1/2 oz. paylod, 1 1/8 oz. paylod of the 12 guage seems excessive.
NJW in AZ