I was not able to find the referenced data sheets, so here are the specifications as of 1967. The reference is from Frankfort Arsenal's Small Arms Pamphlet covering design specifications of listed ammunition.
Cal. .30 AP M2 Bullet weight 158.5 grains to 166 grains
Cal. 7.62mm AP M61 Bullet weight 144 grains to 150.5 grains (cut cannelure)
Cal. 7.62mm AP M61 Bullet weight 145 grains to 150.5 grains (knurled cannelure)
The 30 caliber AP bullet has a flat base and is slightly longer. The 7.62mm AP bullet is shorter and if memory serves, has a slight boat tail. Not sure about the boat tail part, haven't pulled one out of a case in close to 30 years.
A forum community dedicated to M14 and M1A Rifle owners and enthusiasts. Come join the discussion about optics, ammunition, gunsmithing, styles, reviews, accessories, Modern, Devine, SOCOM, EBR, classifieds, and more!