I agree with the other posters, who mentioned
it should not be a surprise gift. The ladies want
the event, more than the item.
To make it special, take her to a range to rent a bunch
of pistols for her to try.
Then take her to Carrabas, or a nice lunch somewhere.
Then, if she has a general idea of what she likes,
perhaps a trip to the gun store.
She's going to consider her time with
you special that day, not the gun...