"After all, the extractor is cut with dummy rounds in the charge holes..."
That may be done in some armorers class but I beg leave to doubt it is done that way at the factory. If you look at the extractor and the way it is made, you will see that pins or not, dummy rounds or not, it is impossible for the extractor to become mis-aligned with the chambers. (Look at the points of the "star" and how they mate with the cuts in the cylinder.)
I will also note that it is quite common for older S&Ws not to time up fully when the cylinder is held back and it is very common for older Colts not to come up all the way until the trigger is pulled. The real test is if the firing pin strikes the primer in its center every time. If it does, any slop under abnormal conditions is not important; if it does not, that revolver needs work.