Any ranged weapon can have a rangefinder built into it. Such a weapon takes no penalty when used to attack target at short range. Thus, a blaster pistol with a rangefinder upgrade takes no range penalty on attacks against targets up to 40 squares away.

This is essentially an improved version of a targeting scope, and thus its benefits do not stack with those of targeting scopes. However a weapon can have both a rangefinder and a targeting scope, using the latter only when aiming at targets at medium or long range.

Source: Scum and Villainy, p. 43