No that is an actual level of odds that 1300 rated player catches a GM level mistake, 2700 doesn't play perfect but close to it you know.
I think about the only chance is to catch him out with an opening novelty which the GM doesn't know or underestimates. Anything over 10 moves and the 1300 wll be so far behind he wont be able to win with an extra queen.
My probability function also says that the chances are decreasing when game is getting longer and longer. But the problem is finding an underestimated novelty against 2700 rated player is probably harder, they just memorize the moves of the opening you choose .
Nevertheless, if there is a moment to strike at the GM, it is at the opening .
No that is an actual level of odds that 1300 rated player catches a GM level mistake, 2700 doesn't play perfect but close to it you know.
I think about the only chance is to catch him out with an opening novelty which the GM doesn't know or underestimates. Anything over 10 moves and the 1300 wll be so far behind he wont be able to win with an extra queen.