I called the rangers that work in that area. They said while the road is closed about a mile out from the shooting range, you're still able to hike in and use the range. You MUST hike to the range to fire, as firing on the roads and surrounding area NOT in the range is not allowed as well.
From the Forest Service website:
Area(s): South Platte Ranger District
Date(s): Jun 1, 2011 - Dec 31, 2011
Pursuant to Title 16 U.S.C. § 551, and Title 36, C.F.R. § 261.50 (a), the following act is prohibited on a portion of National Forest System lands within the South Platte Ranger District of the Pike National Forest, Park County, State of Colorado, hereinafter referred to as the Restricted Area. This order is necessary for short-term resource protection.
PROHIBITIONS:
Operating motorized vehicles in the Restricted Area, from June 1, 2011, through midnight, December 31, 2011, is prohibited. (36 C.F.R. § 261.54(a))