A good OH shooter is giving away points if they don't BS. In general I would say that grouping will at least double shooting fixed at 200 yards and I can think of only two guys that ever were competitive with fixed. Merrill Martin was one of them and I'm not sure if he ever won a ASSRA match but, I do know that he placed in the top three at times. His chamber and throating were of the CBA BR style with a straight neck, ball seat and a long lead. I don't know if anyone chambers the 32/40 with a straight neck but, if they don't and don't use the above type throating, accuracy with fixed will be severly lacking. Even with that type chamber/throat, I doubt that you can get better than 3" for 10 shots at 200 and I would think that one or two of the ten would drop out of that.
I believe that even if your a poor OH shooter like me, that fixed will hurt you. You may luck into a better shot because the "angle of despersion" went opposite of you unsteadiness but, it will also go in the same direction of it as many times as not
Back in '93 when Jim Feren shot the still standing, record OH 241- 5c, I do not think he would have even considered a good fixed load, even with his skill it would have probably cost him at least 5 points.
OT but, BTW, just for the record his 241 - 5c was not a re-entery match as is listed, it was part of his record 100 shot score and just think what it could have been with a rifle that would shoot 250's instead of a 245 - 246 rifle.
Frank