would the .416 Barrett be too much, especially for a sniper rifle?

i had a random unrelated question. 

if one wanted to improve on the 50BMG, and necked it down to about 11.3mm, would it still be able to match the same muzzle energy, in other words you are makeing an equivalent of 6.8mm in 50bmg.

and would this result in better retained energy>?

smg762 said:

if one wanted to improve on the 50BMG, and necked it down to about 11.3mm, would it still be able to match the same muzzle energy,

Most likely yes. You can use a rather long and heavy bullet and increase MV so the ME stays the same.

I am not sure this is a sensible approach though. .50 allready has high MV. Going faster will have an effect on barrel life. The main limit of .50 is its small caliber. This limits payload volume. You want to go even smaller. Makes very little sense to me.

smg762 said:

and would this result in better retained energy>?

Propably. But if you want more retained energy just use a heavy longe range .50 bullet. The "common" long range load is a 750 gr bullet that is ~100 gr heavier than the typical MG grade ammo. There also is a 800 gr bullet COTS available.

schnuersi said:

Propably. But if you want more retained energy just use a heavy longe range .50 bullet. The "common" long range load is a 750 gr bullet that is ~100 gr heavier than the typical MG grade ammo. There also is a 800 gr bullet COTS available.

That's because the current M33 ball was designed to ballistically match the WWII-era M8 API that was optimized for air-to-air role.

The original M1923 ball used a 802 gr bullet launched at a very sedate velocity (770 m/s, very similar to the various 13.2 mm Hotchkiss), then was replaced with the faster M1 ball (750 gr @854 m/s), and finally the M2 ball (~700 gr @895 m/s).

As an anti-personnel loading yes. As an anti-material loading, no. Like others have said, not enough payload volume. 

Also, logistics. Lots of places are set up to make 12.7 NATO or 12.7x108; necked-down versions of these would require some new tooling at least.

If you want a smaller than .50 rifle, get one of the .338s.