Small Arms Test Range
Building number 620c

Building 620 was built in 1928-29 as part of the consolidated testing area created in the rehabilitation work done after the 1926 explosion. It had a two-story section built into an embankment, with a concrete foundation and tile walls, containing an office, firing room, instrument room, storage room, and a lavatory and change room in the basement/first floor. Stretching to the north-northeast of this section was a 12-foot wide, 195-foot long 1-story firing range. This section had 7-foot high concrete exterior walls with hollow tile above, steel trusses, and a shed roof. A third 7-foot high concrete interior wall ran down the center of the structure, creating two parallel firing ranges. A sand pit caught the bullets at the north end. In 1940, an additional range designed as a flare test tunnel was built abutting the west side of the first range, forming a gable roof. It was the same width as the original double range, and had its own instrument room and double-door entrance at the south end, where it formed an "L" with the original office section of the building. It also had a small ante-room at the northwest corner of the building, built partly into an embankment and accessed by an exterior stairwell. This room provided access to the detonation chamber at the far north end of the building, which had a 5-foot diameter draft stack installed in the ceiling. Movable screens were provided for measuring light intensity within the tunnel proper, and other equipment measured the candle power, burn rate, and color value of tracers, flares, and candles. The 1940 range was built of hollow tiles with reinforced concrete piers. A wooden covered walkway ran along the exterior of the east side of the building and connected Building 620 to Building 620C.

Building Information

Year Built



Concrete foundation, hollow tile and concrete walls, shingle roof with steel trusses; wood-framed covered walkway on concrete piers


Ranges each 1 story, 12’ x 195’; Office section 2 stories, 30’ x 32’


Second range added 1940; frame additions on east side 1943 and 1944 (these are Building 620C); interior dividing wall removed from east range, and hollow tile infill and windows on east wall replaced with concrete 1969

Ready, Aim, Fire!

Building 620 Range 2

Small-caliber weapons and ammunition were tested at Building 620 for over 60 years.  During that time, evolving instrumentation for measurement and recording made tests and calibrations ever more precise.  But the basics of test firing remained essentially unchanged.  Technicians set up their instruments, attached the weapon to the mount, and fired - usually repeated rounds, in order to obtain reliable statistical data. These procedures continue at Picatinny’s Armament Technology Facility.

Modern firing range in building 7 Modern firing range in building 7

Two of the three modern firing ranges at Picatinny's state-of-the-art facility

I Worked Here

Vicki Duke

Female silhoutte

Vicki Duke took a job in small-caliber weapons testing at Picatinny in 1983. She describes what it was like to join the mostly-male team, and the test firing routine at Building 620. 

Building 620 Corridor

Firing Range No. 1 in Building 620.

Original Building

Original building plans have not survived, but photographs taken in 1929 show the original Small Arms Range (Building T-822, later re-numbered 620) constructed in Picatinny's new Ordnance Testing Area.

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building No. 620building No. 620

Evolving Facilities

  • Extant plan sheets show not only the addition of the west range in 1940, but also some of the new features installed and changes made in the ranges over time. For instance, a concrete gun mount and attached chamber for measuring smoke density was installed in the west half of the original firing range in 1942, and in 1946 a new "universal" gun mount was installed in the firing room. New electrical connections were installed in the detonation chamber for an M36 detonator in 1952, and the west range was partitioned into separate rooms in 1955. In 1969, a full rehabilitation program included the removal of the center wall within the original test range and filling in the windows along the east wall with concrete block, along with upgrades to systems. A water bullet trap and flume were added to the west range in 1977 (see tab), and at the same time a new barricade with viewing window was installed for the east range. Examples of drawings are shown here. The photograph shows an instrument setup in the west range.

  • Building 620 Foundation Plan

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  • Building 620 Construction Detail Plan

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  • Building 620 Building Alteration Plan

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  • .22 caliber gun mount with lumiline screens, recoil pendulum, and recovery box

    .22 caliber gun mount with lumiline screens, recoil pendulum, and recovery box

  • Building 620 Addition Plan

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  • Building 620 Smoke Chamber Detail Plan

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  • Building 620 Gun Mount Detail Plan

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Water Trap

In 1977, the flare tunnel (west range) detonating chamber was converted into a water bullet trap. This trap consisted of a steel plate with a small opening through which rounds were fired, backed by an apparatus with two large truck tires through which water was pumped to trap bullets. A similar water trap is still used in the new Armament Technology Facility at Picatinny.

Building 620 Inside The Water Trap Recovery Room

Inside the water trap recovery room

Building 620 Gun Mount Base and Water Trap Opening

Gun mount base and water trap opening

  • I Worked Here

    Vicki Duke

    Female silhoutte

    Vicki Duke, who worked at Building 620 in the 1980s, describes the water trap.  

    Building 620 Barricade and Viewing Window

    Barricade and viewing window at north end of west range

Additional Building Photographs

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