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Wednesday, 29 July 2015

Bullet Penetration & 'M K R':

Currently the 'Standard' for assessing penetration and comparing the effectiveness of projectiles is ballistic gelatine - but it wasn't always the way.

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.

Fun eh.

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.
Ordnance Ballistic Gel is a tissue simulant only .. anyone looking for an exact replica of an animal torso is really wasting their time as there are as usual - too many variables.

- 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.

Marty K.