LFI, biggest gun store between the Mississippi and California, 50 minutes North off I-25 in Johnstown. Best selection of just about everything in Colorado. The collection of Kimber Serial #1s is worth the gas money for sure. Scheels is is 200 yards from them and a great place to visit and drool. Drive right on by Cabelas.

Mile High Shooting in Erie on the way back if you are at all into Precision.

Machine Gun Tours in Lakewood has some really cool Class III stuff, lots of ARs, not much hunting stuff.

Ark, Damage Factory and Bowers are smaller, great service at all three. If you do Damage Factory and Bowers, Centennial Gun Club is really close to them as well.