Indoor shooting ranges are very popular with
law enforcement agencies across the country. These ranges are
favorable as they offer protection from adverse weather
conditions, may be operated year round day or night, and have
the flexibility to control and change conditions for special
training scenarios. The encroachment of residential communities
into rural areas has also contributed to shooting range
facilities moving indoors, it becomes safer for the community.
The adverse tradeoffs of the benefits of shooting indoors are
the exposure of
airborne lead particles and noise levels during live fire
exercises.
The airborne lead particle issue has been
widely documented and addressed on many levels. The hazardous
impulse noise levels and the resulting hearing loss have not
received the same attention but is a phenomenon that demands
attention. The majority of indoor firearms shooting facilities
in America have deficient or no acoustical treatments. This is
very costly for the law enforcement agencies as worker
compensation claims paid out for hearing loss claims exceeds
$100,000,000 each year and is rising.
The muzzle blast of a firearm that is
discharged produces impulse noise peak levels in excess of 165
dB (decibels). This impulse noise exceeds the Occupational
Safety and Health Administration (OSHA), National Institute for
Occupational Safety and Health (NIOSH) and American Conference
of Government Industrial Hygienist peak sound pressure limits of
140dB. Prolonged exposure to impulse noise will result in
hearing loss.
The most common reason for not acoustically
treating a shooting range under construction is oversight. The
architect, the law enforcement agency and the builder generally
overlook it. Shooting range design and construction is highly
specialized; function and safety of the shooter is the highest
priority in design development. Acoustical treatments should be
as high priority as are the ventilation system for lead
particles and the bullet trap to contain rounds fired. The
criteria will not be met with perforated metal panels or rubber
materials. To
complete construction of an indoor shooting range facility and
discover that it is too loud to shoot in is a very costly
mistake. In most cases this oversight will cause a range shut
down due to workers compensation concerns and OSHA complaints
until the range noise problem is remedied.
The acoustical objective is to achieve a low
reverberation time in the treated range. The design is to
include acoustical treatments to all exposed wall surfaces and
exposed overhead baffles or safety ceilings.
Critical Design Criteria
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Ricochets: The treatments are to be uniform
without dimensional deviations on the surfaces to reduce
ricochets due to misfires. The treatments should allow
penetration of bullets without reducing the treatments
acoustical performance. The treatments are certainly not to be
of any metal products. |
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Fire concerns: Un-burnt powder must be
removed as part of regular range
maintenance. Treatment durability must allow for this
maintenance without damaging or hindering the acoustical
performance. Treatments are to be fire rated with a label of
“non-combustible” to ensure against fire by accidental
ignition of un-burnt powder. The treatments should not be of
any foam products, which contain polymers. |
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Acoustical performance: Treatments must
absorb a minimum of 95% of all muzzle
blast energy. The intensity of gunfire noise requires superior
acoustical performance to provide the low reverberation times
necessary to reduce the impulse noise levels of an indoor
shooting range. |
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Weather concerns: Most indoor shooting
ranges constructed are not entirely
enclosed. Some designs expose the vertical area above the saw
tooth baffle design and or rear walls to the exterior
environment. Acoustical treatments must be able to perform in
exterior environments such as rain, heat, humidity, and
sub-freezing temperatures without reducing material life or
compromising acoustical performance. |
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Ease of installation and cost:
Implementation of a well designed acoustical
treatment during original construction is highly cost
effective compared to retrofitting an existing range.
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With
the Troy System™:
