Some bullet traps include a negative-pressure system to filter dust from air within the impact zone and capture area.
For use with multiple firing positions, the helical chamber often resembles a horizontal pipe, into which bullets are directed by upper and lower steel plates.
[2] Impact-type bullet traps typically use vertical or angled 500 Brinell scale steel plate at least 3⁄8 in (9.5 mm) thick for centrefire cartridges.
The small plates can be easily changed as frequently as necessary whilst the main back wall will need little maintenance from occasional scattered fire.
In some circumstances a wall of railway ties, intact vehicle tires or blocks of shock-attenuating concrete (SACON) or other proprietary materials may be used.
Such systems require less space than earthen berms whilst being quieter than steel impact or deceleration traps, which can be a significant consideration for urban outdoor range complexes.
A discharge will be safely contained in the event of a mechanical failure during loading, or a procedural error during unloading that leaves a round chambered.