[USS Alaska]

Why don’t they make M-16s in 7.62?

Then they'd have to call them M-21s.

[Spktyr]

The M-21 is a .308 M14-based rifle used as a sniping rifle.

But they do make the M-16 in .308. It’s called the AR-10. Or the DPMS .308. Or the Bushmaster XM-15 in .308.