Friday, February 13, 2015

Trapping bullets with a water trap

Sometimes a reloader needs to capture a fired bullet to evaluate the reload's potential terminal ballistics characteristics.  This is commonly done with a "water trap".

A wire basket from an old, chest freezer, a plastic garbage bag, a picnic table and off screen to the left, a snow bank.

Dimensions of the wire basket are 20" long by 10" wide by 7" tall for a calculated volume of a bit less than 7 gallons.  In metric, that is 500mm long by 250mm wide by 175mm tall with a volume of about 27 liters.

Momentarily distracted by a passing thought of caution I added a chunk of firewood at the end of the trap.  I did not need to.

The most energetic round I load.  30-06, 180 grain Remington Core-Lokt soft point.  57.5 grains if IMR 4350.  2800 fps.  Provided a hunter can hit the target, this load is the cat's meow for such moose, elk, grizzly bears and amorous Holstein bulls as wander about Southern Michigan.

The view downrange.

Houston, we have collateral damages.  The zero temperature this morning probably made the plastic of the table brittle.  I will have to fix that before Mrs ERJ notices.  I will use yellow pine.

Do you see the bullet?

It is right in the middle of the red circle.

A closer view.  There were no signs that the bullet hit the chunk of firewood.
The basket is reusable.

This is what the reloader wants to see.  How widely did it expand.  How much weight is retained.

The smooth face of this bullet is indicative of a bullet that has been trapped in water.  The diameter was 0.575"

Conclusions:

  • The top of the picnic table needed replacement anyway.
  • The 20" long water trap stopped a stout, big game bullet.
  • The 20" long water trap should be capable of stopping handgun bullets if they expand.
  • It is always prudent to have a backstop.  Bullets do not always travel in a straight line after hitting the surface of the trap.
  • It was easy to find the expanded bullet to collect expansion and retained weight data.
  • The wire basket is reusable.  The big game bullet bent it up somewhat, but the big game round delivered 9.5 times more energy than a 9mm handgun round.
  • Garbage bags are cheap.

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