Id of three .50BMG ball projectiles

I have 2 .50BMG projectiles that I would like to ID , they are on the left side of the photo in the 1st pic, and seem to have lost their color tips.

The bottom of the projectiles.


Projectile LHS, with extra serrated cannelure AP ( probably M1) or API
RHS, Normal Ball.

Different cannelures ( Cut groove and knurled groove).
Cut grooves are usually done to AP Projectiles, but can also be found on normal Ball; Knurled Groove is Ball. ( manufacturing Variations from Facotry to Factory.)

Doc AV

Thanks Doc!

Now for a 2nd question. All 3 are ball rounds. Different model #'s or just manufacture’s options? Note the one in the middle with the smaller diameter hole

On your first posted picture with the two bullets, the base of the projectile on the left appears to have a foil closure seal. If so, it is probably APIT. The best way to ID these is to weigh them IMO. JH

Ball pix (L-R):

M2 Ball

First Pic (L-R):
M20 APIT if it has a foil closure disc on the base (not too obvious in the pic what it looks like). If not a closure disk, then M2 AP

(Assuming US production of components, foreign can vary)