Damage is set at 111, same as the RM277 and the MCX Spear.
Ammo capacity starts at 20 rounds in a mag with 4 spare mags at a total of 80 rounds
Ammo pickup rate is set to 2-4.5 at base, same as the MCX Spear/RM277. For a weapon aiming to get 2-3 headshots to kill on average, you should find this to be plenty of ammo pickup.
The fire rate matches BOCW, at a rather slow 535 RPM. This makes the EM2 rather controllable under automatic fire, but also means DPS racing bulldozers might give you issues...

Accuracy starts at a fairly respectable base of 64 and can be made pinpoint accurate with mods.
Stability starts at an average of 48 and can be further increased by mods. The kick should be rather consistent and not that big of an issue given how slow the EM2 fires.
Concealment is average at a base of 15 and the EM2 lacks ways to increase its concealment. While you "can" make it work, the EM2 is not a rifle optimized for dodge setups.

Otherwise, most of the attachments from BOCW are here, with some being purely cosmetic like the grip tape/stocks, while the barrels and magazines are going to be the heart of your build. You do start out with the scope and do have the option to use the backup iron sight.

The only notable attachment is the Task Force Barrel, which behaves mostly like its pre-patch BOCW version: a noticeable damage boost at the expense of increased recoil. The Task Force barrel should bump your damage up to ~128 damage, bringing you to exactly enough damage to consistently two shot headshot most enemies in the game without skills.