Dont have that version handy atm, in the Deluxe Edition on pg 75, part of the Situational Combat Rules section which lists out a bunch of specific cases.
Ranged Weapons in Close Combat
No ranged weapon larger than a pistol may be fired at
adjacent foes engaged in melee. Larger weapons may be
used as clubs, however. Pistols can be fired in close combat,
but since the defender is actively fighting back, the TN for the
Shooting roll is his Parry rather than the standard TN of 4.
That means it’s harder to hit someone who’s wrestling with
your character in melee than someone a few feet further away
who isn’t actively wrestling with your hero.
I tell a lie, apparently I do have Explorers handy. Page 70, part of Special Rules with the same subheading of Ranged Weapons in Close Combat. Looks like the text is unchanged in the two editions to me.
I probably went too easy on my guys with how their assault by the steam wagons went. Still nearly killed several of them, but that was their own fault really. That ogre is a badass though.