3.51 WinMBT patch

[Grumbler]

Maybe it ain't broken?

http://www.survivalmonkey.com/50BMG_ammo_Primer.htm

This source and others (google it) give between 16 and 22 mm of penetration at 500 meters for various type of .50 bullets.
IIRC the SLAP round is twice that. When you consider spalling and the effect of multiple hits within the same basic area, I think the .50 is UNDER RATED in the game. Very few light vehicles have more then 25mm of armor.
When it comes to M-Kills, the 12.7 mm round has more then enough energy to break track and knock sprockets around. While the running gear on a tank is good steel, it isn't armor, so a .50 should be able to shoot thru bogies, sprockets, road wheels, track, etc, at under 10 hexes.

In SP terms, pen of 2 at 16 hexes for standard M2 AP round.