The base version of the medium halftrack 251, the 251/1, was divided into 2 models/revisions.
"A" was meant to carry a Panzergrenadier group with 2 LMG42 (1 or 2 MG 34 or 42 were mounted on the halftrack later on, this came down to personal preference/MG availability, many 251/1 received a shield for the mounted frontal MG42, but the LMG(s) could also be mounted on the sides or in the rear), "B" was meant to carry 2 heavy MG squads (from the Coy's heavy platoon). The LMG's (from the PG group) could be mounted on the halftrack's side and rear, if the respective mount was available.
The 251's MG could be detached from the vehicle and taken into combat but was often usually kept on the vehicle to allow for suppressive/support fire from the safety of the vehicle, so it would only change the combat efficiency, if the game would distuingish between mounted/unmounted state of the vehicle gun and (the troop's) dismounted state. If it would be considered by the engine, then the vehicle MG would be ready to fire at once, while the PG group would have to dismount and deploy their 2 leMGs (or mount these 2 guns on the vehicle side or rear), first.
I am not sure how the game engine is handling this. Does it put in a deployment time even for the vehicle's mounted frontal/rear MG?
The various direct fire guns mounted on the several halftrack versions (like MGs, AT guns, inf guns, Flak guns, turreted 20-mm gun, flamethrower, etc. etc.) were usually ready to fire within seconds to less than a minute (for the higher calibre guns), just the preparation of the mounted weapons for indirect fire (mortars, 28-mm anti-tank rifle, inf gun in indirect fire mode, etc.) may have taken a bit longer.