I suggest Parro's, they're on US 2, just west of Waterbury. I've done business with them, and will again. They have most brands of handguns and some rifles. They definitely have Glock stuff.
Or take a trip to Williston, get off I-89 at Exit 12, hang a right onto VT 2A, then a left onto US 2, and pull in right next to the Mobil on the corner of US 2 and VT 2A. The Powderhorn. Doesn't look like much on the outside, but the biggest amount of non-PC firearms in the state, short of Century's warehouse. You won't regret the trip. Lots of stuff, bring money, lots of it. He's reasonable, but you'll want to buy stuff.