Got some interesting answers, even one or two answered the question who have tried it. I know my rifle may or may not shoot he same as other rifles of the same, I know its about harmonics ( Duh!, don't forget velocity and scatter nodes. ). And the one about the SKS I think is posted on the wrong forum cuz its got nothing to do with anything here.
Recent findings with my 91/30 bayo on vs bayo off, I found the groups to be the same, only the POI had changed to about 8 inches higher at 75 yards with the bayo completely removed. Home loads were the only scenario where I can improve the groupings by anything to speak of. Very little effect on group size ( but still raised POI) on czeck surplus and the more recent Russian surplus, but the Russian Surplus has so far shown to be more accurate and hotter ammo than Czeck surplus.
If its nice this weekend ( not -30 c), I'll get out and try it myself. Just trying to get a heads up of what to expect at the range, from others who have made this comparisons. I'll bring large cardboard backing for the targets to be sure I know where I'm hitting. I don't have a problem to tune in some more home loads, and probably will. I'm just thinking that if it doesn't make much of a difference, I'd just assume take it off for hunting season. As said, just looking for cause and affect from others who have actually gone through the motions.
Someone mentioned that they get funny looks at the range when shooting with extended bayonets. Who cares what they think? If they know anything about firearms, they will know what you are doing and why. Funny comments and questions just make the ignorance light bulb flash red. Personally, I like the bayonets on. Some rifles were meant to be shot with bayo affixed.