Just use real people. [;)]

Go to the store in the gelatin section.  Find something named Knox Gelatin.  It is NOT cheap.  About $14/lb.  This is what the FBI uses to creat ballistic gelatin.  I have about 4lbs of it in block form in my fridge at this very moment.  And believe me, you will need about 4lbs to create a block that will stop a rifle round.  3lbs minimum for a 55gr .223.

If you need help in making some, please e-mail me privately.

I should add that you can get it much cheaper, but only if you order it in bulk directly from Knox.  In that case, it's only about $5/lb, but you have to order about 50lbs...

I have all the equations worked out for how much you need per volume of water...it was a PITA, but I got it done and have done some tests successfully using a .32ACP and a .223.  But, as those are part of a more extensive test, I can't discuss the matter until the project is finished.  At that point, there will be much more in depth info posted here by myself and another board member who shall remain anonymous.

Don't worry.  There will be a plethora of pics.  But, don't hold your breath.  It may be several months.  I think the members here will be very impressed with the experiment.