Baffles, Berms and Backstops

By: Clark Vargas

Pursuant to prior range industry paper on this subject, one specifically by my good friend Dave Luke and shown in the proceeding of the 3rd National Range Symposium of 1996, this peer

review paper is undertaken to document more recent design standards for ranges, solidifying the “No Blue Sky” concept and “Ballistic Sand” 1:1 suggested slopes, design of manger traps,

etc., detailed and specific civilian range minimum design specifications were last presented in the 1999 “NRA Source Book.”
To properly evaluate bullet containment, which is what Baffles, Berms and Backstop do, it is necessary that we evaluate the process of planning range design, construction and operations

problem by considering 4 E’s, of Range Design.

1. The Business Plan and Range Master Plan:
Developing the Business Plan is essential to determine if the range is viable or not and is the Basis of the Range Master Plan.
The Master Plan focuses on the how, what, when, why and whom of the range. These documents are developed during the Master Planning phase and well prior to the design and construction

phases of a range complex. Subsequent, Safety and Long Range Plans are the living document of a range that must be continually reviewed and updated.
If planning is left to the end or a range is not planned, the facility owner/operator will find some undesirable surprises as he prepares to open for business and some of these surprises

may shut him down. The Safety and Long Range Plans are an important part of the Master Plan.

2. The 4-Es of Range Design:
The 4-Es must be used at every step of developing a shooting range. The 4-Es are: Evaluate, Engineer, Educate and Enforcement.

2.1. Evaluate: The range owner/planner design must evaluate the needs of the prospective user presented in the business plan and identify the specific shooting disciplines to be

conducted on the facility. Evaluate how many shooting activities can be conducted on the same ranges, not simultaneously. Review schedules for the various activities to ensure there are

no conflicts in range design and subsequently range usage result. This is an important consideration. While there are a few different shooting activities that can be compatible and lend

themselves to simultaneous range use, most are not.

2.2. Engineer: Each range or range complex must be engineered to accommodate the specific disciplines and activities which have been evaluated on their own as appropriate and are to be

conducted on the same piece of ground/range. Intimate knowledge by the Engineer/Designer of each shooting discipline and their rule book or curriculum specifying the detailed

requirements (if applicable) of each activity static or dynamic is essential. Each discipline’s requirements will have to be considered in detail to ensure no conflicts in firing line

design, target line location, target placement and target set up operation, etc. Time efficiency is also an important consideration when switching from one activity to another. While it

is possible to conduct multiple shooting activities on the same range, single purpose ranges are best and it will require deliberate thought and careful consideration to ensure possible

conflicts are insignificant and kept to a minimum. Once the design criteria have been established and constructed, it will be important for the owner/operator to truly understand that

there will be very little room for change in use without returning to the evaluation phase with additional engineering to retrofit the range to accommodate the new activity.

2.3. Educate: The operators and those who will be using the facility (users) must be educated in the specific Courses of Fire that are acceptable at said range and which firearms,

firearm calibers, positions that can be used (standing, sitting/kneeling, prone), types of firing (slow fire only, rapid fire, etc.) Static and Dynamic are but a few topics that should

be taken into consideration from inception as to how the range will or may be used.
Briefings on the etiquette of firearms safety, how and when to approach the firing line, how and when to change targets, commands that will be used-and their meanings, range officer

authority, etc. Careful explanation in this area will reasonably ensure that the facility will not be used outside of its design capability and thereby cause problems for the range.

2.4. Enforcement: This is the final phase of the 4-Es and ultimately is the glue that will hold all these considerations together into one cohesive package. You are giving instructions

to be obeyed. You are not giving advice. Enforcement solidifies the Planning and Safety Plan. The owner/operator must consider the specific range rules methods and actions that will be

employed to ensure the range is always used well within the design limits. Ultimately, it will be the responsibility of the owners/operators to determine the range use, assuring

adherence to the rules and regulations established.

3. Purpose of backstops, baffle berms and baffles:
Erecting baffle berms and backstops are a necessary and a minimum requirement for range owners/operators who do not control 1.5 miles downrange for pistol or 3.5 miles downrange for high

powered rifle, with appropriate 5 degree left and right safety zones.
I believe and all of us would readily agree that the full surface danger zone (SDZ) ranges are the exception rather than the rule. They are a concept of the past. Therefore, the primary

purpose of the construction of backstops, berms and baffles is to protect against the injury of people, damage to property or both, when a full Surface danger Zone (SDZ) can not be

provided. A secondary benefit is to permit the periodic recovery of lead projectiles, a recoverable and recyclable metal resource that can contribute to the positive cash flow of a range

facility.

4. Projectile/bullet containment.
It is the ultimate responsibility of the range owners/operators to ensure that the projectiles fired on their range are contained within the range property boundaries. While it is

entirely possible for an existing range facility to be grandfathered against noise complaints, it is totally unlikely that any governmental body would make the same concession concerning

safety. Therefore, it is paramount that shooting range owners/operators continually evaluate the shooting activities permitted and the requirements necessary to ensure those activities

can be conducted with projectile/bullet containment within the property as the result. The level of requirement necessary for the projectile/bullet containment on the property of a

shooting range facility will dictate the extent of the baffle construction. Side berms and backstop shall always stop the bullets. Baffles shall manage the bullets and its flight

characteristic so it remains on the property.

5. Shooting safety fan.
It is important to frequently remember that while specific range safety fans are indicated in numerous design manuals, these safety fans presume a free and open range.
As more and more controls and barriers are added to the design (both administrative and physical), the range SDZ becomes smaller until eventually the range SDZ equals the exterior edges

of the barriers of the backstop and side berms. This point is not specifically made in the “NRA Source Book” and also is not a logical conclusion by those not familiar with range design,

construction and civilian operation. These same regulatory folks seize on a specification and fail to understand that by adding controls or barriers, the range SDZ is changed and

significantly reduced. Backstops and side berms alone do not remove the requirement of an analysis of the SDZ. Baffles, berms and backstops can limit the SDZ to the range property lines.

6. Backstops
The backstop provides the primary impact area for the bullets being fired and to terminate their kinetic energy under normal conditions. They also prevent the bullet from leaving the

range property. The backstop also serves as the storage device for bullets until they are recycled. Refer to prior peer review papers on Ballistic Sand. An important point to remember is

the construction of a proper backstop will not eliminate the requirement to provide a downrange safety fan beyond the backstop for the design type of firearm or caliber allowed to be

fired without baffles.
It shall always terminate the bullet at the property line. The probability of an accidental (firearm malfunction) or unintentional discharge where the bullet escapes the range without

first impacting the backstop must be evaluated and considered as the range design proceeds. This must be evaluated in the context that the surrounding land use changes and encroachments

by development will result.

A major consideration in initial design is to provide sufficient space behind backstop for ease of backstop repair and lead recovery of skips, ricochets and tidily-wings. All too often,

ranges are constructed allowing for the maximum number of firing points and distances to targets in the shortest acceptable width and distance to property lines but with insufficient

space to allow regular maintenance or heavy equipment access all around the range and to the range firing or target line. If insufficient space is not provided, problems will result.

Special consideration is to be provided to interior access and sufficient space, 30 feet minimum behind fixed target lines, for maneuverability of heavy equipment between the target line

and the backstop.

The best outdoor backstop is a manmade earth embankment with a 10 foot high ballistic sand projectile containment face or a natural hill of appropriate size and shape that meets the

specific requirements of the particular range.

Alternative backstops may be used when appropriate earthworks are not available. Preferred backstops include: 1) prepared naturally occurring hills or mountainsides (shaping the slope

will likely be required), 2) earthen backstops constructed from clean fill, 3) earthen backstops constructed from broken material (concrete or asphalt cores) and covered with clean fill

dirt, 4) earthen backstops constructed from clean fill and stabilized internally, and 5) fabricated backstops using steel, concrete, or wooden cribs.

Backstop heights can vary according to the site and use. General dimensions are as follows:

A. Height. A minimum height of a constructed earth backstop is 20 feet. The minimum is acceptable, but 25 feet is now also being recommended. This height is the compacted or settled

height. Height should also be consistent with other barriers that will be incorporated into the range design.
A backstop, ricochet catcher, ricochet baffle or “manger trap” can be installed to reduce the number of bullets escaping the range by tidily winks or sliding up the face of the backstop.

The manger trap is effective in retaining those ricochets that occur off the face of the backstop. While the distance traveled by such a ricochet would be a nominal 50 to 100 yards, this

factor needs to be included in the design calculations, if insufficient distance to the property line is not available. This device is installed parallel to the floor and into the

backstop face and extends to the toe of the slope. The ricochet catcher is typically 15 to 18 feet above the range floor, measured vertically from the ground surface at the target line.

This prevents direct bullet impact into the catcher. The ricochet catcher must be impenetrable to ricochets and should extend completely from side to side and connect the sidewalls or as

substantiated by the design. If overhead baffles are employed, the top of the backstop need only be 2 feet higher than the ricochet catcher. Specific construction details of the ricochet

catcher will dictate the amount of material needed to ensure that the catcher is held securely in place.

B. Width. The width of the backstop should extend at least 5 feet beyond the intersection of the 5º ricochet line from the outside targets/firing position. If the range has high side

berms that closely match the height of the backstop then this requirement need not apply. Keep in mind that earthmoving repair equipment needs adequate area to maneuver and access to

work behind the target line. Therefore, this allowance may need to be greater.

C. Slopes. The backstop side slope (side facing the shooter) ballistically must be as steep as close as possible to 45º (1:1) and not less than 2:1. If a soil analysis determines that

the soil will not support 3:2 slopes to maintain the minimum required slope angle, it will be more economical to remove the poor soils and replace them with more suitable material.

Special techniques may be required to stabilize the backstop above and behind the ballistic sand impact zone.

In poor soil areas, structurally designed soils may be used on the offside of the backstop to stabilize the soil material.

Sandbags, yes; never automobile tires, may be incorporated to maintain the bullet impact side of the slope. There are many other materials and methods that can be used to stabilize the

slope until vegetation can be established. Special netting material is especially useful to establish plants. Heavy vegetation such as large plants or trees should not be permitted on

the range side of the backstops.

Steel backstops are also an acceptable but more expensive alternative when soils are inadequate. The primary drawback is the initial cost. However, if the quantity of shooting is

substantial, the ease of recovering lead may quickly offset the initial cost. Basic maintenance costs also will be lower. Concrete foundation will be required to set and support this

type of backstop. Because these backstops are constructed to the same specifications as indoor range backstops, the 20 feet earthen barrier behind them will be needed.

7. Side berms and walls
These protective barriers may be constructed from earth, precast concrete panels, concrete wall masonry walls, “wooden cribs”, wooden box-type structures filled with pea-gravel, crushed

rocks, chopped rubber tires filled with soil and/or poured concrete walls or panels. The specific type of structure will depend on available space, type of range being built and the

relative initial cost. A major consideration that should be evaluated during the initial planning process is the long-term maintenance cost of the barrier being considered. Most times it

is far more cost-effective to select the construction material that will provide the longest life while requiring the least maintenance. Wood crib baffle require maintenance and if

constant hit, they last only 10 to 18 years.

Exposed tires present problems such as bullet bounce-back that must be addressed before they are used and make recycling of projectiles impossible. If earthen side berms are selected,

the construction methods will be the same as that used for the construction of the backstop. If concrete panels are selected, then site work will be required to build their foundations.

Concrete panels can be tipped into place or set into place using a crane. If masonry walls are selected, skilled masons should be used. Foundations will be required to prevent settling

or major damage caused by ground shifting. Structural engineers should design and licensed concrete companies should be employed to erect concrete structures, especially in earthquake-

prone areas. If concrete walls (precast or poured-in-place panels) are selected, the specifications cited in the “NRA Source Book” should be strictly adhered to. If crib walls are used,

they have to be tested in accordance with the Source Book.

Generally, earthmoving equipment will be used to construct the earthen backstops. If earthen side berms are the choice, then doing earthwork all at once while the equipment is onsite to

construct the side berms is the most cost effective. Side berms generally vary in dimensions according to the specific need. If a side berm is to be used also as a backstop, as some

shooting activities may require, the safety fan rotates and the 180º rule comes into effect. When this instance occurs, the side berm is considered to be part of the backstop and should

conform to the same specifications as the backstop.

In this situation, the overall height of the side berm, for at least that portion that is used as a backstop, shall be the same as the backstop. It is important to remind all range

owners/operators to carefully evaluate the shooting activities to be allowed in their range facility and include them in the master plan.

7.1 Side berm, walls or barrier specifications are as follows:

7.1.1. Height. Generally, side berms, walls or barriers are suggested to be a minimum of 8 feet high, with 10 to 12 feet recommended if the range is going to be subsequently baffled.

Side berms may be used on all ranges and on ranges that go a distance of 1,000 yards. Side berms, walls or barriers stop bullets and are used to allow shooters and range personnel to use

adjacent ranges simultaneously. Another reminder: backstops, side berms, walls or barriers in and of themselves may not eliminate the requirement for a safety fan area.

7.1.2. Length. Except as indicated above, side berms may be the same height and the full length of the range-from the backstop back to 5ft behind the most distant firing line.

7.1.3. Slope. The range side (the side facing the shooter) of the side berm should be as steep as is possible or as flat as desired. These specifications are the same as those for the

backstop.

Masonry walls are an alternative construction method, as are precast panels. The repair work for damaged masonry walls is labor intensive and precast panel sections, if damaged, may not

be repairable on site and have to be removed and replaced. Initially, an additional number of the precast panels can be purchased. Masonry walls using concrete block shall be fully

grouted and filled with concrete to add strength and impenetrability to the structure. Masonry walls should be reasonably protected against bullet strikes and shall not be placed

immediately adjacent to a firing lane.

Wooden crib side baffles filled with selected materials may be used and are easy to construct if properly designed, but are not easily repaired or maintained.

Obviously, the designs for side baffles will depend upon local site conditions and available materials cost. A point to be emphasized about wooden box side baffles is that they must be

tested before being built to ensure that they will stop the bullet for the designed caliber used in the design. It is the rare exception that will require this type of structure to be

more than 3 inches thick consisting of two sheets of ¾ plywood and 3 ½ rock. A structure made to the total thickness of 6 inches will stop all bullets from normally accepted sporting

arms and individual infantry military small arms.

For legal purposes, when wood rock crib baffles are used, construct a test panel and conduct the appropriate U.L. tests before committing to any major construction expense. Test twice

before building once. Refer to the “NRA Source Book” for dimensions and drawings on how to construct the test panel.

Precast concrete panels set at angles on each side of a static range can economically prevent bullets, regardless of the angle fired laterally, from escaping the range. Panels can be

manufactured onsite and tipped into place. These 4” barriers withstand most bullet strikes without major damage. Stringent range rules will prevent shooters from inadvertently firing

into the barriers. Shooters must demonstrate the appropriate skill necessary not to cause damage to range equipment.

8. Safety baffles
The term safety baffle or overhead safety baffle defines the structure which is used to restrict fired bullets over to backstop and side berms to smaller areas than would otherwise be

possible without them.

Safety baffles differ significantly from sound baffles, which are designed to absorb or redirect sound waves.

Safety baffles are designed to redirect and limit the bullet travel no further than the property line.

The basic design concept is the “No Blue Sky” concept. This means that baffles are erected so that the shooter, from the shooting position allowed (or permitted), cannot see any sky

downrange, either over the top of the backstop or to the sides of the range. The baffles ballistic material then contains the bullet.

Safety baffles may be overhead, on the ground, on top of the backstop, in the roof of the firing line cover up to a 30º elevation, in the form of an elongated box, or as a completed

enclosed tunnel.

The principle behind the design is to equip a range with baffles so that if a fired bullet leaves the confines of the range proper, it will fall to earth within a smaller, more

predictable area that is acceptable within the range property, to protect the people or property and adjacent ranges.

If overhead safety baffles are not designed and installed properly, they can cause problems. They may redirect the fired bullet in the wrong direction, back to the shooter, may not

absorb the fired bullet as intended, or there may be gaps that will permit a bullet to escape the range. For any range on which overhead baffles are planned, carefully analyze the

application beforehand and seek a professional design.

8.1 General specifications say that safety baffles must:

8.1.1. Be impenetrable or defeat and limit travel or design calibers to be used on the facility.

8.1.2. Be a minimum of 4-feet-tall for vertical baffles.

8.1.3. Be relatively maintenance-free.

8.1.4. If using concrete must be designed to provide maximum spans l. Span length between columns is a product of lane width.

The specific design and number of baffles that will be needed to protect a given area will be dictated by the amount of free space around a particular range facility that the range can

limit access to.

Overhead baffles are a standard vertical 4 feet high with the bottom edge set 7 to 7.5 feet above the horizontal surface of the range. The width dimensions are the width of the range so

no side light is seen or as properly designed.

For baffles constructed from plywood and filled with high-density material, use 3/4-inch marine plywood on the firing line side, 5/8-inch on the downrange side, and built into a box with

an inside dimension equal to the minimum width of a standard 2×4-inch piece of lumber. Again, the baffle must be tested before use.

Baffles may be built by laminated wood and steel or by a special concrete panel design. Laminating baffles using plywood and 10-gauge steel requires a lamination thickness of three

sheets of plywood with two sheets of steel sandwiched between. Nominally the lamination thickness is 2.5 inches.
Slanted overhead baffles for dynamic ranges are 12 to 24 feet wide and set at a 25-degree angle to the ground as measured from the front edge (the firing line edge being higher than the

rear edge). The slanted overhead baffles are a minimum of 3-inches-thick, prestressed concrete slabs, and must pass 3,000-pound, 28-day, compressive strength test.

9. Ground Baffle
It also is important to keep in mind that it may be necessary to incorporate a series of ground baffles within the overall design. Ground baffles reduce the ground surface area that a

bullet might strike. When properly designed and installed, ground baffles do reduce ricochets, but do not totally eliminate them. When the downrange area is viewed from the firing line,

the shooter will see overhead baffles, ground baffles and the target and backstop immediately behind the target. No blue sky will be visible, nor will any of the horizontal ground

surfaces of the range.

9.1 Generally, ground baffles must be:

9.1.1. Impenetrable.

9.1.2. Minimum height to correspond with the placement and horizontal surface area to be masked. Multiple ground baffles may be required for a 50 or 100 yard range. The goal is to mask

the range floor beyond the first baffle.

9.1.3. Relatively maintenance free. Ground baffles are designed to meet the needs of a particular facility.

The dimensions for ground baffles are a minimum of 3 inches thick, if made of plywood, and may be backed up by an earthen berm. If a wooden top cap is used, particular attention should

be paid to the direction of the wood grain. It should always curve downward and the top cap is cut at 45º angle side down range

Materials for ground baffles may be concrete (firing line side surfaces should be covered by 1” wood stock covered to prevent bullets from being redirected toward the firing line,

pressure-treated wood, steel (firing line side surface covered to prevent bullets from being redirected toward the firing line, or earth or a combination.