Types ammo carried in a platoon - quite a few.

5.56 Nato - for the general squad rifles
7.62 Nato - for the sharp shooter and as link for the GPMG
9x19mm - for Pistols
12 guage - for semi auto shotgun - used for breeching doors etc. and for close range support.

Then you add in 40mm underslung grenade launchers, plus hand grenades etc.

Sniper pairs tend to be independent of main platoons so will carry own ammo. 338 Lapua for long gun, 7.62 for support weapon and 9mm for pistols