How generous of you to offer. [And he sees no reason not to accept it, even if wasn't something he was fishing for. There's nothing supernatural about being a good shot or fast learner, and anyone who is suspicious of him is someone he wants to keep close.] Thank you.
But as things are it wouldn't do to waste bullets frivolously, of course. [Learning to shoot is frivolous? Well, in this particular situation, with the both of them talking about it more as a pastime, it kind of is.] Do you hunt?