Advanced technology not authorized for public use. Rarely seen out of the Alliance Military’s hands, and for good reason; they’re extremely lethal in the hands of anyone. As seen in Heart Of Gold, Rance Burgess’ model was a silk trigger, active-return bolt laser and a lot lighter than it looked. Unlike Burgess?' weapon, Alliance issued version don't yet have the auto-target adjust; his was crafted special.
The Serenity Role Playing Game text lists the laser pistol as having a 10 shot magazine. However this conflicts with both direct observation of the events in Heart Of Gold as well as a more detailed analysis of the episode.
Based on evidence from Heart Of Gold, some approximations can be as to battery capacity.
DVD time indices are accurate only to the second, giving us a precision of .5s for all measurments. With that approximation, we say that the shot that killed Nandi and the 4 fired at Mal were all .5 seconds long.
Operating on the assumption that one "shot" is a .5 second discharge from the battery, we can then conclude that the 4-5 second "slashing" attack was equivilent to 8-10 conventional discharges.
This fixes the lower limit at 13-15 shots per battery. This assumes all shots are of uniform power, as well as other themodynamic and electrodynamic simplifications.