Reduced charges of rifle powders (even the quickly burning N110, which is good for full-power Hornet loads) shall not generate high enough chamber pressure for regular combustion. Surfaces of rifle powder kernels are usually coated with chemicals (deterrents), which shall reduce flammability of powder, and combustion of it until the coated surfaces of the kernels are burned through. Reduced charge shall usually become extinguished, leaving the bullet lodged in the bore, but sometimes the powder shall smoulder and generate detonating mixture of gasses.
When this coctail of gasses shall explode by heat and/or pressure inside the rifle chamber and bore, the shooter has a true bomb in his/her hands. It may be hard to believe the disaster what a considerably sub-minimum charge 0.20 gram of shotshell powder is able to generate behind 8 grams bullet in the .308 Winchester rifle: Shooter lost almost his life or at least his left arm. A charge 1.10 gram of the same kind of powder and same kind of bullet was completely safe in use: Five or six consecutive shots gave exactly same muzzle velocity. Accuracy is of "Bench Rest" class. Minimum charge of this very powder VV N320 is 0.40 gram in .308 Win behind the bullet LAPUA S374, but two foolhardy Finnish lads didn't believe it without a painful experience. Another almost lost his eyesight. He loaded 0.20 gram of N320 behind a jacketed D-46 bullet with weight 11 grams, while minimum charge of powder N320 is ca. 0.50 gram!