Well, yeah, in most movies characters use single-action guns. Still, even with semi-auto weapons I doubt Jamie would have faired much better. The only thing that would've really worked was going full auto and then having multiple weapons ready to go to. A full-auto magazine would be spent in seconds. So either more magazines would be needed with some serious skills in speed-loading/reloading or multiple weapons.
Giving Jamie all of the benefit, however, I don't think he would've faired better than Adam.