This mania for hyper fast loads is getting out if hand. Lead loads, I used in my youth, would have been from 1150-1250 and we're extremely effective. Steel at long range has such a bad reputation that everyone thinks all you need to do is drive it faster but past 30 yards it has lost so much velocity that the difference between a 1200 and 1500fps load is marginal. You get five to ten yards more effective range at most, which you could do almost as well just by increasing to larger shot size. You can't pass shoot, or sky bust as some do with steel. It does kick more, stress parts and shooter more but for what I see as marginal gains.
I was looking at low pressure lead load for a 20 and noted Longshot could produce 7k 7/8 ounce loads at 1350. Too fast for my use because of the recoil that would damage old wood. So I tried to reduce the load down to about 1200 fps but when I tested them the velocity went from 1135-1275, which was not a consistent load. Worse was that the loads were tested in warm weather, where velocity tends to be more consultant. In real cold I expect the spread to be greater. If the light loads had been consistent I would have sent them out for pressure testing and velocity confirmation. So I crossed Longshot off my light load, in a small bore list to keep velocity and pressure down to shoot in light doubles. It would be nice to reduce my powder inventory to less than ten different powders to load everything I need.