diameter is .3125 grade 8 lock washer, standard.
A washer which is usually round with a centrally located hole. Its edges and two bearing surfaces are so designed that applied pressure brings into play the spring tension and/or frictional locking principle which materially resists any tendency toward turning. It may be made of one or two pieces
NSN 6135-01-426-8282
NSN 5895-00-226-3109
NSN 6110-01-299-1655
NSN 5950-01-098-8634
NSN 5996-00-972-7331
NSN 5996-01-126-2156
NSN 6105-00-166-2154
NSN 6320-00-284-1524
NSN 5835-01-077-6278
NSN 6620-01-244-0260
NSN 5950-01-027-1459
NSN 7035-00-553-6951