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, 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 size	Thread pitches	A — flats max / min	H — head height max / min	J — slot width max / min	T — slot depth max / min
#4 · 0.112 in	48 UNF / 40 UNC	0.187 / 0.181	0.060 / 0.049	0.039 / 0.031	0.036 / 0.023
#6 · 0.138 in	40 UNF / 32 UNC	0.250 / 0.244	0.093 / 0.080	0.048 / 0.039	0.046 / 0.033
#8 · 0.164 in	36 UNF / 32 UNC	0.250 / 0.244	0.110 / 0.096	0.054 / 0.045	0.066 / 0.052
#10 · 0.190 in	32 UNF / 24 UNC	0.312 / 0.305	0.120 / 0.105	0.060 / 0.050	0.072 / 0.057
1/4 in	28 UNF / 20 UNC	0.375 / 0.367	0.190 / 0.172	0.075 / 0.064	0.101 / 0.083
5/16 in	24 UNF / 18 UNC	0.500 / 0.489	0.230 / 0.208	0.084 / 0.072	0.122 / 0.100
3/8 in	24 UNF / 16 UNC	0.562 / 0.551	0.295 / 0.270	0.094 / 0.081	0.156 / 0.131