I can give examples of the use of this expression. Even if I can guess what it means, I don't have any adequate ideas.
The phrase has been used in this book[1]
1) The shot told; the Irrepressible was silenced; and I profited by the chance to pour in a broadside of another sort.
2) The shot told: they were notoriously the closest-fisted couple in the village.
3) It was about the time that his disappointment became known to everybody, and the shot told.
The relevant definition of shot in the Oxford English Dictionary is:
figurative. A remark aimed at some one, esp. in order to wound. Also cheap shot (North American colloquial).
The relevant definition for tell from the OED is:
to be effective or efficacious; to have the desired effect
In other words, it means that the remark hit where it was aimed.
Originally the phrase "the shot told" meant that a gunshot had struck the target, and had an effect. You can find it used in this sense in historical novels set during the Napoleonic Wars, for example.
Later, as a metaphor, it indicates that sarcasm, irony, or other possibly hostile speech had had an effect on the person to whom it was addressed.
