To spawn guns and mags work fine.
Ex:
/additem ORGM.HKUMP
/additem ORGM.HKUMPMag

But, to spawn ammo, don't work.
I Tried:
/additem ORGM.Ammo_45ACP_FMJ_Box
/additem "ORGM.Ammo_45ACP_FMJ_Box"
/additem "playername" "ORGM.Ammo_45ACP_FMJ_Box"
/additem \"playername\" \"ORGM.Ammo_45ACP_FMJ_Box\"
/additem "ORGM.Ammo_45ACP"
/additem ORGM.Ammo_45ACP
/additem "ORGM.Ammo 45ACP"
/additem "playername" "ORGM.Ammo_45ACP"
/additem "playername" "ORGM.Ammo 45ACP"
/additem "playername" "ORGM.Ammo_45ACP" 5
and many others variations...

I tried too:
/additem "playername" "ORGM.Ammo45ACP"
/additem ORGM.Ammo45ACP ;
/additem ORGM.Ammo45ACPFMJBox

but says:
item ORGM.Ammo45ACPFMJBox doesn't exist.

What am I doing wrong?