I recently signed up for a free online drawing to win a Beretta ARX 100*. While I'm not going to lose sleep over my chances of winning, it did make me wonder. It's a modular design that can be customized for different calibers: 5.52 NATO, 5.45 Soviet, 6.8 Remington SPC, and 7.62x39 Soviet. What caliber would you choose and why? I would lean toward the 7.62x39, but obviously people have their favorites.
*They said ARX 160, but I presume they mean the civvie version.