Make a single shot grenade launcher like the M79. With normal ammunition (the underbarrel grenade launcher has a very small supply). Working on the principle of a sub-barrel grenade launcher. In the vicinity, the shell does not explode.
naahh engineer has enough AV options, give the nadelauncher to the infil .. for real .. undernadelaunchers need to be supported by ammunitionpouches .. also engineer has ammobox for his underbarreloptions .. no need for the engi there ..
of course it isn´t, because it´s primarily focused to indirectly oneshot infantry so not only does it lack 2 or 3 rounds of ammo but needs a bit of a AV buff