Download Report

Our backstop is a standard upswept and down swept slanted steel plate range. The Plum High
School rifle range backstop is almost identical to ours except that their room is taller thus their range
is higher and their range is not as wide. A Construction grade steel frame stands independent of the
rear wall yet attached to the wall so that it can not upset. On this construction frame are 3/8 inch
steel plates (standard design criteria for .22 cal is ¼ inch steel) sloped at approximately 30 degrees
with the horizontal (standard design criteria suggest 25 to 45 degrees). These plates are 4 feet wide
and 4 feet long and they stretch the entire width of the back wall. (A 2 foot section was added in the
middle to cover the entire 26 foot width of the room)
At the connecting point between the two steel plates a 1 foot by 4 foot 3/8 inch steel decelerating
plate was placed horizontal to the floor. The lower plate rests on the steel frame. The upper plate
hangs by 4 chains from two 4 by 4 crossbeams placed on the steel frame. The deceleration plate
hangs from a chain from the upper plate. (See Diagram exhibit 5)
The front of the steel frame is finished in 1/8 inch plywood so that any backsplash is contained
within the backstop. Seven shooting ports faced with homasote were cut into the plywood to
provide shooting lanes that are replaceable. Periodic replacement of these panels is planned, it
appears the panels will need to be replaced on a yearly basis. (see pictures at bottom of document)
Bullets entering the lower portion of the backstop are deflected up to the deceleration plate where
they stop. Much of the residue slides back down the plate and rests on a ledge between the plate and
the front. This facilitates easy removal. Any bullets entering the top of the backstop deflects toward
the deceleration plate and stops. Most of this residue bounces off the plate and ends up in the front
ledge also. Cleaning is done by removing the front homasote panels and vacuuming the residue out
with a HEPA vacuum.
The sides, floor and ceiling of the room are constructed of concrete or concrete block. Since only
½ inch of concrete is needed to stop a .22 cal bullet at a 90 degree angle (see ex. 7 table) any
glancing blow of a bullet on either the ceiling, floor or sides of the room would result in a deflection
down range toward the backstop and a loss of much of the bullets energy. All lighting in the room
is up lighting and has steel deflection shields on the under side facing the shooter. The only entrance
to the room is behind the firing line and controlled by a red warning light during range operations.
I have provided several pictures of other ranges using similar backstops. Example 6 is a
professional backstop designed for high power rifles. (they use a smaller slope due to the increased
energy) Example 8 is a standard portable backstop available at many sports stores which has ½ of
the design. It is a down swept plate at a 45 degree angle. The entire backstop is made of ¼ inch
steel. I own 2 of these backstops and they work flawlessly. Example 9 is a backstop plan found on
the internet which is also a down swept steel plane. This author claims he used 3/8 inch steel and it
works for bullet calibers up to .44 mag. This makes me think the 3/8 inch steel in our backstop is a
bit of overkill, but better be safe then sorry.
Fig 1. Internal structure of backstop showing sloped plates and internal deceleration plate.
Fig 2 Completed front of backstop showing shooting ports.