 Greener fitted the hollow base of an oval bullet with a wooden plug that more reliably forced the base of the bullet to expand and catch the rifling.Tests proved that Greener's bullet was extremely effective, but the military rejected it because, being two parts, they judged it as too complicated to produce.The soft lead Minié ball was first introduced in 1847 by Claude-Étienne Minié, a captain in the French Army.