| FASTENER LENGTH | 3.219 INCHES MINIMUM AND 3.281 INCHES MAXIMUM |
| HARDNESS RATING | 36.0 ROCKWELL C MINIMUM AND 45.0 ROCKWELL C MAXIMUM OVERALL |
| HEAD DIAMETER | 0.429 INCHES MINIMUM AND 0.438 INCHES MAXIMUM |
| HEAD HEIGHT | 0.306 INCHES MINIMUM AND 0.312 INCHES MAXIMUM |
| HEAD STYLE | FLAT CHAMFER |
| INTERNAL DRIVE STYLE | HEXAGON |
| MATERIAL DOCUMENT AND CLASSIFICATION | 66 FED STD SINGLE MATERIAL RESPONSE OVERALL |
| MATERIAL | STEEL OVERALL |
| MINIMUM TENSILE STRENGTH | 160000 POUNDS PER SQUARE INCH |
| MINIMUM YIELD STRENGTH | 130000 POUNDS PER SQUARE INCH |
| NOMINAL THREAD DIAMETER | 0.312 INCHES |
| NONDEFINITIVE SPEC/STD DATA | 1 TYPE |
| WIDTH ACROSS FLATS | 0.156 INCHES NOMINAL |
| SURFACE TREATMENT DOCUMENT AND CLASSIFICATION | QQ-P-416,TY 2,CL 3 FED SPEC 1ST TREATMENT RESPONSE AND QQ-Z-325,TY 2,CL 3 FED SPEC 2ND TREATMENT RESPONSE OVERALL |
| SURFACE TREATMENT | CADMIUM AND CHROMATE OR ZINC AND CHROMATE OVERALL |
| THREAD CLASS | 3A |
| THREAD DIRECTION | RIGHT-HAND |
| THREAD LENGTH | 1.625 INCHES MINIMUM |
| THREAD QUANTITY PER INCH | 18 |
| THREAD SERIES DESIGNATOR | UNC |