i assume you're living in the us? not sure what the laws are, i'd imagine they don't make it particularly easy, especially if they think you may be leaving the US with aforementioned device (i.e. export).
best thing is to check the batf's site,
http://www.atf.gov/
also, it may be easier to talk to someone on the phone. you should be able to find the local branch of the atf (in the town you're living, or purchaser is living). should be on the atf's site, or look in the phone book. i'd probably suggest calling the local atf.
although if you're not living in the US, and you're having a noncitizen purchasing it for you for export, i'd personally suggest probably steering clear of that.
also, steer clear of the glocks! yuck! the usp may be a few hundred bones more than a glock, but there's a reason. you get what you pay for.
