"the DREAD's ammunition will be .308 and .50 caliber round metal balls (steel, tungsten, tungsten carbide, ceramic-coated tungsten, etc...) that will be literally spun out of the weapon at speeds as high as 8000 fps (give or take a few hundred feet-per-second) at rather extreme rpm's, striking their targets with overwhelming and devastating firepower."
so, they would not break up in the air since they would be made of very tough materials. the main concern with propelling obejects at those speeds seems to be friction with air, hence the cermamic coating. ceramics have incredible heat resistant properties. the space shuttle tiles are made of ceramics. they are able to withstand temperatures of thousands of degrees kelvin... to get a general idea of the heat they shield from...
"The Shuttle reenters at Mach 18--that's 18 times the speed of sound. If all the energy of the air pushed out of the way by the shuttle were converted to heat, it would reach a temperature equal to the local atmospheric temperature (250 degrees Kelvin) multiplied by 18 squared; that's 80,000 K. But not all the energy is converted to heat; the actual temperature is "only" 2000 K. Yet even that is about a third of the temperature of the surface of the Sun"