We had the same problem last year and we were also feeding HSC Finisher. We were feeding two steers and one was fine and the other could shoot it through a screen door! We did everything we could think of and finally the only thing that helped him was being on more complete feed and less hay. The hay we were feeding was just basic grass hay, but apparently the combination of his feed and the amount of hay we were feeding was just not right for him. We tried oats, beet pulp, probios and he was tested for parasites. As a young calf this steer was always a little looser than the others. I would definitely have him checked for parasites as was previously suggested.
On another note we are feeding two more steers this year the same feed and essentially the same hay and neither one of them have a problem with it.