Of all the wetpack tests I've done this was one of the more surprising. Usually a normal caliber and weight (like 180 gr, 30 cal) high power, controlled expanding, premium jacketed rifle bullet traveling at a normal 100 yd hunting impact velocity will penetrate, in my media, somewhere around 14-18". The media is always the same- bundles of 100% water saturated phone books with a bone simulation hardwood insert of 1 3/4 - 2" thickness placed behind the first bundle... or about 4-6" in from the entry face.
Just out of curiosity one day I loaded up an original Civil War issue 69 caliber US military rifle, an M 1861 Navy (Naval), aka Plymouth rifle, with a Lyman #68569 Minie' and tested it. The moderate FFG BP load used should have yielded about 800-850 fps at the media. The hollow based Minie's I cast for this rifle are of near pure lead, a nominal .690" diameter and weigh about 730 grains. The result was almost 20" of straight line, point forward penetration! Plus, as shown in the photo, the Minie' suffered very little deformation and nearly 100% weight retention. Go figure? Maybe a basic bullet penetration demo comparing the concepts of momentum to kinetic energy- I dunno?
