I have Michael Yardley's little book on gunfitting. Great insight. I think an enthusiastic, experienced shooter, with the knowledge of that book and some aptitude, can figure out his or her own dimensions. Experienced shooters will have already gravitated to their dimensions in adjustable comb and LOP target guns or by going thru numerous guns. I've never had a professional fitting, but I can recite my dimensions and I would really question a pro that suggested dimensions much different.
For me, I have no differences in tolerance of general gun fit dimensions for o/u, sxs, auto, or pump guns. I do believe shooters have a lot of tolerance on LOP and in general, I would rather have a gun shorter than my ideal LOP rather than longer. That is: I can tolerate a 1/2" shorter better than 1/2" longer.
