Right.. I think most women in such a situation would be too terrified to try to put on a convincing act. And even if they did, what would plan "B" be if the rapist decided to follow through anyway?
Not all rapes are "terrifying". That's a misrepresentation, since the vast majority are not cases of strangers leaping out of dark alleyways and putting a knife to your neck. The most common perpetrators of rape are husbands and boyfriends, according to statistics in England, where 97% of the callers to Rape Crises Lines knew their attackers beforehand. (
linky) So you're basically advocating wives (or passing vigilantes) shoot their husbands, daughters shoot their fathers, students shooting their classmates, etc. for what many people might argue (albeit incorrectly) might actually be a simple case of miscommunication or the need for psychiatric counselling.
Don't get me wrong, I'm not being an apologist here, I only think it's of great benefit for both men and women to have an accurate picture of what "rape" actually is in the vast majority of cases. Insisting that death should be an appropriate punishment for rape overvalues female chastity in a way I find disturbing and archaic.
Yes there are serial rapists around who target strangers, but it's a drop in the pond in comparison to the whole. Probably similar to the ratio of people murdered by serial killers to killings overall, including crimes of passion and manslaughter (as opposed to first degree murder), although that's just a guess.
There just aren't enough violent, predatory sociopaths in the world to justify carrying a gun just in case you happen to have the misfortune to cross paths with one, considering it is infinitely MORE likely you will use it inappropriately yourself in dark times, or your children will play with it, or someone will steal it to sell on the black market.