Best gun stores are Jensen Arms in Loveland and Rocky Mountain Shooter's Supply in Ft Collins. RMSS has an indoor range as well.
Actually IN Longmont the best gun place I've found is Grandpa's Pawn on 3rd & Main. Lots of used stuff and they'll order new stuff, and have some new on hand. Good people as well.
Best shooting club is Northern Colorado Rod & Gun Club. They run several types of shoots, including an IDPA-based Defensive Pistol. Sorta like IDPA, but a little more relaxed.
http://www.ncrgc.org/
Best true IDPA group is Front Range IDPA. Good folks, but a bit of a drive for me.
http://www.coloradoshooting.org/fridpa.htm
There are others around and IPSC types as well.
Best Mexican food we've found in Colorado thus far is Hacienda Colorado in Broomfield. Best in Longmont by far is Efrain's next to the fire station on the Ken Pratt Parkway. Stay away from La Mariposa and El Delicioso. You'd think there'd be all kinds of great Mexican food around here... sadly, no.
Best "pub grub" is The Pump House, at Main and 6th, supposedly really good microbrew beer too... don't drink beer myself.
Best Italian in Longmont is Pinoccio's, a little hole-in-the-wall on Main.
There's also a really good Indian place (Indian as in India) on Main, can't remember the name.
Best breakfasts, and lunch on weekdays, is Lucille's on Kimbark. Neo-Cajun type place.
Great sandwiches at the Bear Rock Cafe on Hover.
Good diner-style food from La Peep and The Egg and I, breakfasts and lunch. Both on Ken Pratt/ Hwy 119.
Lastly, best "general store"/ ranch & home type place is Murdoch's on the north end of Main just before Hwy 66.
Any Longmontians, or is it Longmonters?, care to share where to get ammo, supplies, and which gun stores to visit or not to visit?