Gents:
The recoil issue is from the high velocities. If you throw the shot at moderate velocities, then , using m1v1=m2v2, solving for v2, and then subbing back into Ke = 1/2 Mv^2, you will not have any more recoil than if you shoot lead.
GKT
Good point GKT. Comparing lead to steel requires that we consider both the velocity and the mass of the ejecta.
I think the relevant recoil metric here is the force of the shoulder applied to the gun via the stock to decelerate the gun from v2. That is pretty much the same as the force of the stock head pressing against the action, since most of the gun's mass is in the metal. Since we don't know the time-pressure curve that's hard to calc . I suppose v2 (the final velocity of the gun) is a reasonable proxy. As you rightly point out, this is proportional to the mass and velocity of the ejecta but inversely proportional to the gun's weight. So while we have high velocity of the steel shot working against us, we have the lower mass of a given volume of steel shot (low density), and the higher mass of the gun to help us (in this case the gun is a heavy one even for a 10). So I am not worried about stock failure, if it does fail it would have failed with "regular" loads. I'll put a thick removeable pad on it, that will further reduce the stock head pulse. (taken to an extreme, if we had a 100 lb gun and a one ft recoil pad, the gun would hardly move and any movement would be stopped very gradually, so the stock head would hardly experience any force pulse.)
I don't like Ke as a measure of recoil. But if you use this paradigm, the gun is coming at your shoulder with a certain energy that is proportional to the square of it's recoil velocity, which in turn depends on the mass and velo of the ejecta divided the gun's weight. To stop it, you must apply a force inversely proportional to the distance the gun moves before coming to rest, assuming the force is uniform. So a heavy gun won't be coming very fast, and if you use a recoil pad, you need to apply less force because you have more recoil distance to work with. Standing up has the same effect.. your shoulder can move backward with the gun.
Anyway, to cut a long story short, I think what GKT is saying is the same thing I have been saying, steel doesn't recoil very hard unless there is enough extra shot in the cup to offset the lower density of steel (ie about 1.5x the amount of shot to get almost the same weight of shot as lead in the same shell).
