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 MIL-HDBK-1027/3B
degrees of hardness are available, such as Joalloy AR-360 or Joalloy AR-400.
Other steels are available and other steel companies have equivalents. Such
steels are normally stocked by jobbers supplying mining, heavy engineering,
and highway construction trades. Welding requirements remain the same as for
ASTM A514/A514M.
The design engineer should specify the ASTM or Mil-reference number,
grade of steel and other qualities, and hardness for the specific application.
To ensure that the grade of steel needed is obtained, the purchaser should
deal only with a reputable supplier. While steel plates look alike, there are
significant differences in backstop performance spending upon the hardness
and quality of alloy.
A 3/8-in. (9.5 mm) steel plate treated to 440 BHN when set at an
angle of 42 degrees is sufficient for all handgun cartridges including .44
magnum. A 3/8-in. steel plate treated to 500+BHN when set at 30 degrees will
accommodate cal. 30 (30-06), 7.62 mm, and 5.56 mm ball ammunition, as well as
all pistol calibers.
2.1.5.2
Bullet Trap Plate Thickness. Minimum plate thicknesses shall be as
given in Table 2. Plate joints shall be flush and either buttwelded ground
smooth or butted and bolted to a beck plate on the rear with countersunk heeds
on the face. No joint should be horizontal or located directly behind a
target.
Table 2
Minimum Bullet Trap Plate Thickness
ARMORPLATE
STEEL PLATE
ANGLE FROM
STEELPLATE
550+BHN
(caliber
MIL-S-16216J MIL-A-12560G 440BHN
(degrees)
.22 LR rimfire
42
1/4 (6 mm)
1/4
1/4
1/4
.38 Ball/Wadcutter
42
1/2 (13 mm)
3/8 (10 mm)
1/4
1/4
42
1/2
3/8
1/4
.45 ACP/Wadcutter
1/4
42
.357 mag/9 mm/.30
1/2
3/8
1/4
1/4
cal. Carbine
.44 mag
42
3/8
1/2
1/2
3/8
30
5.56 mm
NR
1/2
NR
3/8
30
7.62 mm
NR
NR
3/8
1/2
30
Cal .30 (30-06)
NR
NR
3/8
1/2
NR - not recommended.
2.1.5.3 Sand Pit. In an existing facility using an inclined plate bullet
trap, a sand pit directly in front of the metal plate bullet stop may be used.
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