Hello, I first read about explosive bullets in a slim little booklet put out by the NRA about American civil war firearms..it might still be available. Anyway, it seems there were explosive bullets used first by the British & later by U.S. troups. Their main purpose was to blow up enemy artilery cassons..but of course there were human targets also..reports from wounded solders told of how they could hear and feel the bullet exploading inside them! Some used percussion type detonation, but most had a 31/4 sec. fuse & sometimes they went off in air.
As a result of this exiting reading...I of course had to try it. I had made a mould for casting .22 lead 40gr. bullets. I drilled out nose in bench lathe for press fit on #4 lead shot. Into this cavity I packed toy gun cap powder & pressed shot in. I shudder even now some 40 years later how I ever came out of these experiments with both my eyes and all ten fingers! Anyway..shooting into 2X4 blocks, bullet always went thru 1st. block..2nd was penetrated about 1/2 way. Splitting open revealed a blackened walnut sized cavity imbedded with lead splinters & only the very base of bullet. Kind of exiting shooting at rocks at night!