EDIT: In the deep past, Mt Grant was used for infantry training (spent blank cartridges are a common find on the lower slopes). During the last decade, the Hawthorne Army Ammunition Depot has been expanded once again for multi-agency use, and there are several live-fire ranges along the lower eastern mountain front. High-angle live fire training is exercised around Rocket Mountain, a complex approximately 15mi to the SE of Mt. Grant. It is unknown if true live fire is currently present on the mountain itself, however given the current levels of training activity on the Depot and security restrictions, obtaining permission through base security to access the summit should be considered mandatory. See the "Red Tape" section for updates.
When significant Nevada peaks are considered, Mt. Grant makes the short list for many reasons. At ~11,270', it is one of the 25 highest named peaks in Nevada, as well as the highpoint of Mineral County. The location, coupled with height and surrounding terrain, make the view from the summit nothing short of spectacular.
The line of sight on a clear day exceeds 130 miles, encompassing Sierra peaks south of the Palisades on one side all the way to peaks near the north end of the Sierra beyond Reno. Countless mountain ranges in the Great Basin are visible to the north, east, and south; from Tohakum Peak near Pyramid Lake to the Kawich Range north of the Nevada Test Site. With the exception of the Sweetwater Range 30 miles to the west, the nearest peaks of similar height are on the Sawtooth Crest almost 50 miles away.
Covering over 40 square miles at its base, massive Mt. Grant takes up a fair amount of real estate, at this time mostly owned by the Hawthorne Army Ammunition Depot (by some accounts the largest such facility in the world). The flanks are cut by several roads, one of which leads to 11,000' just below the peak. Access to the summit is controlled by the Depot, and since 9/11/01 this has been restricted. See the "Red Tape" section below for details.
Wildlife thrives on Mt. Grant, with notables including Bighorn Sheep, Mule Deer, and the occasional feral horse. A significant portion of the mountain is above piñon treeline, and various high-altitude conifer species have found homes on these upper reaches.
The summit is actually a sharp ridge of large 3rd Class talus (~200') that stretches for a few hundred yards. The "official" summit elevation was recorded at a survey point some ~50' lower than the true high point, making Mt. Grant slightly higher in actuality than the USGS admits. Before 9/11/01 a summit register was located at the top, but the current status is unknown.
Much like the Cascade Volcanoes, Mt. Grant's solitary and imposing nature results in the "creates its own weather" phenomenon. High winds in the vicinity of the peak are common; in fact, many sections of the summit ridge are swept clean of any loose material smaller than golf balls --- attesting to the ferocious nature of the airflow along the surface.
Due to the sheer size of the mountain, several route possibilities exist for the hiker. Again, because practically the entire area is owned by the military, permission to access must be gained (see "Red Tape" section below). Of course, the road itself may be driven up (from the NE side), but we are talking hiking here.
To climb "from the base", the shortest routes are on the west side, and are accessed via high-clearance/4wd dirt roads. The "trailheads" would be either Baldwin Canyon or Lapon Canyon, with the hike starting somewhere around ~7000'-8000'. The closest pavement to either of these locations (about 25 miles) is NV State Hwy 338 north of Bridgeport, CA. From Bridgeport, CA State Hwy 182 is taken north for ~15.5mi over the state line to the East Walker/Sweetwater Road. This graded dirt road is followed east for ~15mi into Fletcher Basin and a 4-way dirt intersection. A turn to the north is made, and the road is followed for either ~4mi (for Baldwin Canyon access) or ~10.5mi (for Lapon Canyon access). Due to the nature of the access and hike, skill in using a topographic map is essential for not only navigating to the "trailhead" areas (as far up the canyons that you are able/willing to drive), but also for finding the way in to the peak. There are no sources of water on the peak from this approach.
Climbs from the much lower (~4500'-5000') east side have been done, but are quite steep and strenuous. A walk along the access road up Cottonwood Creek from the town of Walker Lake would involve over 10mi one-way, but would be easy terrain for the most part and include running water most of the way.
2017-October nvsmith adds:
A few comments on Mt Grant access. The only legitimate access to Mt Grant uses the road that goes through Hawthorne Army Ammunition Depot. To gain access the first step is to stop at the base visitor access office. Park just to the left (south) of the main entrance and go to the office. Then there are forms to fill out. After providing proof of identity the forms are fax'ed to Tobyhanna Army Depot and run through some sort of ID check. The process can take as little as an hour; I had to wait a day. Then one contacts the visitor office ahead of time to get the key to the gate. The office is only open Monday through Thursday but the key will be left with the gate guards for weekend access.
Here is what I was sent on October 4, 2017:
"Mt. Grant is now closed for the winter. Next year around middle of May call me at 775-945-7101 and I will let you know if Mt. Grant and Rose Creek are open.
Rose Creek has the cabin and you can stay there after you fill out a Rose Creek and Cabin application. There are no matches, lighters or flame producing items allowed. No alcohol or pets. When you decide you want to go up call me and we can over the application. There is no cost. If you want to fish you have to have a Nevada fishing license.
If you have any more questions please call me and we will get them cleared up and answered."
UPDATE April 2015: The Reno Gazette Journal reports that the Army is actually going to open 'the gate' to Mt. Grant for hikers:
The comparatively mild snow conditions of the Great Basin offer an extended dayhiking season for those who don't like to gear up for major winter alpine adventures. Climbs should be done with at least waterproof boots and gaiters if there is light snow.
Mt. Grant can accumulate more snow than most other Great Basin peaks, so take this into account when doing an off-season expedition. While the snow generally melts quickly off the ridges, some areas (such as N aspects) can harbor decent accumulations of powder usually overlain with a light crust (@^$@*&!!!).
Summer hikes should always involve lots of water, as the evaporation rates get quite high in Nevada.
There are a few lower-altitude water sources on this peak --- however, the feral horses, cows, and deer have the run of the springs, so make sure you treat it thoroughly (i.e. boil, etc)! I say always bring your own....
Times of high snow accumulation and/or muddy conditions will hamper driving efforts on the dirt road sections. Have high-clearance and 4WD (and know how to use it) if you go during a potentially stormy day.
Camping is, of course, free on any BLM land. The nearest lodging, food, or gas available would be in Bridgeport, CA; Yerington, NV; or Hawthorne, NV.
Like most Great Basin peaks, this one requires creative research and a lot of guessing to determine current conditions!
Regional weather may be found by looking up the Hawthorne or Yerington, Nevada forecasts.