Ream is a unique method of rock breaking using high-energy projectile impact. This report describes the most recent in a series of tests demonstrating mining applications for the ream method. In an underground limestone mine at Greer, West Virginia, ream was used to drive a short tunnel and to drill a large-diameter borehole. Along with breakage data from these tests, the goal of the program was to examine environmental problems which might result from the use of cannons underground. A total of 103 shots was used to advance a 14-1/2-ft-high by 10-ft-wide face a distance of 5-1/2 ft. It is estimated that the 9.3-Lb concrete projectiles launched at 5,000 ft per second will break an average of 0.78 Ton of limestone or 67 percent of the 1.125 Tons of granodiorite broken in previous tests. The 9-inch-diameter borehole was drilled horizontally by repeated axial impact for 7 ft, 2-1/2 inches by 21 shots, giving an average of 4.12 Inches per shot. Scaling this result to compressible impact energy yields an estimated 5.8 Inches per shot for a 12.8-Inch-diameter hole, compared with 8 inches per shot for a 16-inch-diameter hole in granodiorite.