They always say the rifles are designed and sighted in to shoot with the bayonet affixed. Pointed out, that is, as in a ‘folded back’ position the harmonics of the barrel will be completely different.
(The fit on all of mine is so tight that it makes it a real chore to remove the poker, which is a problem when you're putting it back in the case or safe.)
But what about rifles that don't have a bayonet? Finn captured or re-built Mosins often don't have the bayonet. Were they adjusted to fire without one? And the snipers sold around here usually don't have one, either. Makes sense that you wouldn't issue a marksman with a front-line infantry close-quarters attachment. I suppose you adjust the scope for the proper point of impact, but if you switch to iron sights are you going to be way off?