Take Mulberry east (CO 14) towards Ault, cross 85, continue on CO14, then take CR 57 (I think, there will be a Pawnee National Grasslands sign on the south east corner of the intersection). Its around 7 miles in, an it is a dirt road. Continue north on CR 57 for two miles, then you can turn right (east) and go half a mile to a bunch of berms where many people shoot, or you can turn left, and there will be a green gate which you can open and go down and there are several shooting stations. Try to get there early, because it tends to get busy rather quickly. Its free, but unregulated, so keep an eye on those around you. Good luck!