because steel is not ballistical equavelent to lead, ( there is a vast difference in weight ), a 6# of steel will lose velocity, compared to a lead shot of 6#, or any other size. The only ballistical source that comes close is some other compounded shot, like ITX, "nice shot", or Kent matrix shot. Gold is better than lead, but it makes the shots more costly. Steel has to be launched with speed of of 1300-1500 FPS, lead does just great at 1050-1200 ft per second. Steel shot and it's super powder required, and shot difference, ( it's lighter and more more cartridge space that lead), lead to horrendous recoil, the experiment continues with, weird shot formations, belted shot, winchester octogon of doom shot, to try to get a high count and make it fly strait, and increase contact, more importantly penetration, on contact. In small gauges in lead as well as steel shot, at least 20 gauges and less, I count ths 16 as well, do not do well with shot of over 5#, which includes a heavy belted 3" mags., any way are we always trying to make a 20, a 12, or the 12 into a 10, with 3 1/2" shells? Enjoy the twenty, use it far away from steel shot zones, or buy the fancy ITX, "nice shot", to stuff into it. The fact that most manufactures make steel , 3 " loads, is testimate that shooters buy them. The birds they put down would be struck as surely with a 2 3/4 inch high velocity load. Fuller testimony that "John shot a bird with his missle of 2#s fired out of high backbored 20 ga. at 70 yards", is expected. Usually it was a bird that got up in range, and succombed to the charge later in flight, by then nobody knows where they were, and the shot becomes heroic. Or a lucky shot which encourages " more lucky shots" henceforth. I would take estimates from someone would patterned steel, moving on a target board at 40 yards, with a chronagraph to measure speed. I have seen reports and have done enough physical investigaton to know the truth. I shoot low velocity, low pressure loads, 4800-6000 PSI, with 6# on pheasants of ITX, or "nice shot" of 1 ounce. Waterfowling I move up to 4# on ducks, and if geese are present I shoot 1 ounce of 2#'s, still at 4800-6000 psi, loads go approximately 1100-1250 FPS. I don't shoot at ranges north of 35-40 yards.