Inch series · controlled reference

Slotted Hex Head Machine Screw Dimensions

Complete nominal-size data from U.S. DoD military standard MS51849A for steel, slotted hex-head machine screws. Both UNF-2A and UNC-2A thread pitches are shown for every nominal size in the sheet.

Source: U.S. DoD MS51849A, Table I; the DoD record remains active and was validated in April 2026.

StandardMS51849A · UNC-2A / UNF-2A · DoD active record
RevisionPrimary-source review · 2026-09
Unitsinches
CAD ORTHOGRAPHIC REFERENCEMS51849A · INCH SERIES REFERENCE
MS51849A slotted hex head machine screw dimension drawing, side view with dimension callouts, 1/4-20 UNC reference size
SIDE VIEW · LENGTH REFERENCE · 1/4-20 UNC
MS51849A slotted hex head machine screw dimension drawing, end view showing slotted hex head and width across flats, 1/4-20 UNC reference size
END VIEW · HEAD / DRIVE · 1/4-20 UNC

Reference size shown: 1/4-20 UNC. The drawing identifies dimension locations only. Use the table for nominal data and confirm the exact product configuration before ordering.

MS51849A Table I — complete nominal-size range
Nominal sizeThread pitchesA — flats max / minH — head height max / minJ — slot width max / minT — slot depth max / min
#4 · 0.112 in48 UNF / 40 UNC0.187 / 0.1810.060 / 0.0490.039 / 0.0310.036 / 0.023
#6 · 0.138 in40 UNF / 32 UNC0.250 / 0.2440.093 / 0.0800.048 / 0.0390.046 / 0.033
#8 · 0.164 in36 UNF / 32 UNC0.250 / 0.2440.110 / 0.0960.054 / 0.0450.066 / 0.052
#10 · 0.190 in32 UNF / 24 UNC0.312 / 0.3050.120 / 0.1050.060 / 0.0500.072 / 0.057
1/4 in28 UNF / 20 UNC0.375 / 0.3670.190 / 0.1720.075 / 0.0640.101 / 0.083
5/16 in24 UNF / 18 UNC0.500 / 0.4890.230 / 0.2080.084 / 0.0720.122 / 0.100
3/8 in24 UNF / 16 UNC0.562 / 0.5510.295 / 0.2700.094 / 0.0810.156 / 0.131

Drawing is an original dimension-location illustration, not a manufacturing drawing. Verify material, finish, thread series, length and MS51849 part number before release or installation.

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