Whit,
Love those milk jug tests! Thank you for the link to your videos - great stuff.
In an experiment I did with the same type of jugs, I came up with this information:
"Since claims are most frequently made that 10% gelatin solution is pretty close to live target tissue, the following stats use that medium. To translate it back into distances that the same bullet would travel in water, you use the multiplier of 2 to 1, more or less. One source says that 2.25 is more accurate; and another source says that you should use 1.8 with stacked milk cartons because of the cardboard in between each segment (the milk container packaging material)."
(
http://www.levergunscommunity.com/viewt ... 4&start=40 )
Those particular jugs showed me that a slug that penetrated in 10" of gelatin would penetrate 15" of water, or specifically 1.5x. That is, water pentration using that shape of a jug is 1.5x the penetration in gelatin (or roughly, flesh). See:
http://www.levergunscommunity.com/viewt ... 4&start=80
So... penetration through 5 plastic 6-inch milk jugs, capped, stacked sequentially without outside clamping pressure (as in your test) should be about equal to 2/3 that distance in gelatin, FYI. At least that was what happened with pistol bullets.
If the longer rifle bullets follow suit with those jugs, that gives you:
5 six-inch jugs = 30 inches;
Multiplier of .66667 [or, 2/3] * 30 inches = 20 inches
Your 5 jug water penetration should approximate 20 inches of gelatin media.