tround said:
I think that the 0,338 must replace the GPMGs in 7,62x51 . But it can't remplace the 12,7 because
it was designed to be the minimum anti material caliber . (see Pershing specifications in 1918 and simply the MG TUF IN 13,2X92sr) . The french attempt to decrease the energy of HMG were failures : 9x66 10x71 11x78 cartridges . Even today the 12,7 remain the minimum anti material caliber .
Nobody should care about such entirely obsolete opinions.
Modern AFV are armoured in protection levels
- some against 7.52 mm long cartridge AP
- few types against 12.7 mm API
- many against 14.5mm API
the next real step is then 30 mm APDS or even APFSDS
.338 can penetrate the first category just as .50 can, and .50 can penetrate no other categories except with the still relatively exotic SLAP cartridges
The only advantage of .50 is that it can penetrate the first category at worse angles or longer distances, which isn't very important since such targets are very often poorly armed themselves (7.62 only) and could be engaged at short ranges.
The huge advantage of .338 is the much greater quantity of ammunition that can be carried inside the vehicle and the much higher practical rate of fire (.50 practical rate of fire in ground combat is very limited because ammo is so short; you'd normally want about 900 rpm).
Meanwhile, .338 is just as the .50 valuable for penetrating light cover (walls, trees, sandbags) and likely better for suppression (higher RoF, smoother manual aim).
By the way; the Polish 7.92 mm anti-tank rifle was no more or less a failure than 12.7, 14.5 or 15 mm ATRs. There's no minimum calibre for light armour penetration cast ins tone at all. In fact, 7.62x51 mm SLAP is very much capable against most APCs.