My penetrating gaze (!) spotted that the 1883 Springfield Minie rifle was rated as able to penetrate four inches of soft pine with its heavy bullet at 1,000 yards - while expected to hit a target the size of a mounted man at 600 yards.
I've also read discussion about how far a WW2 Lee-Enfield .303" penetrated into (or through) piled dirt or sand - such as the ramparts in front of trenches. - It seems that the bullet will penetrate further at long range than it will closer .. as it tends to break-up on impact with a hard substance at the close higher velocity.
Trying to ignore just what type of bullet we are using - the question immediately arises as to how soft is the soft pine used and how rock-filled or granular is the earth or sand.
The guys on the range nowadays sometimes pile-up wet newspapers or soaked telephone books to get some measure of what is happening, and a row of water filled plastic jugs or bottles gives a spectacle to watch - you can have fun counting the blown containers and looking for the slug.
- Hickok45 enjoys shooting bottles of coloured fizzy drink for effect - and that's got to be the best use for dyed liquid sugar you could think-of.
I've seen tests in gun magazines where straw-board or cardboard is stacked in racks as below:
- and one of the fifty year-old books I just bought was using plastic bags stuffed with cotton waste then filled with water .. all the air was carefully squeezed-out before use.
In the 'OLDEN DAYS' when I first started reading anything that I could find on shooting - 'Duct Seal' or damp potters clay - even blocks of soap were popular for measuring the depth and then recovering projectiles - and to date it is sometimes used by air gun shooters as a bullet trap.
All those old ideas were useful - but they all were only good for comparisons made on the day rather than a measurement. The 10% Ballistic Gel used currently does provide a 'standard' and has the great advantage of being clear so that the "wound path" can be viewed and measured - and the projectiles are more readily traced and extracted if wanted.
- Way back (in the "Olden Days") I was aghast when I had the 'MKR' for cluster-bombs explained (Maximum Kill Rate). - I was told the then standard method - of tieing various livestock to a grid pattern of stakes - on a bombing range and then "counting heads" after the test drop to assess the percentage kill .. which is somewhat less outrageous than loading them onto a plane with Red Cross markings and flying them to Viet Nam for trials.