What game ruling determines the difference between a light and heavy blaster pistol? Is it the weapon's base damage? Heavy does 7, all others do 6 or less. Or in the wepaon description which is only mentioned IIRC in CRB, page 161-2 and no splat as I'm AFB but starting to look through them 😄

I don't think there even is ruling, or a game mechanic that cares about whether a pistol is called light or heavy. It's just fluff. They'd both use Ranged-Light.

I'm not sure what the significance is, but it would usually be in the name or in the fluff. Looking at my lists, it seems that once they hit 7 damage, they're referred to as Heavy Blaster Pistols. There are probably exceptions and outliers, and I don't have Fly Casual to reference, and that book has some odd pistol statblocks that may defy classification.

ex. Renegade Heavy Blaster Pistol, HH-50 Heavy Blaster Pistol, DL-7H Heavy Blaster Pistol.

Usually a heavy blaster runs out of ammo earlier (3T or Despair instead of just Despair), but that may not always be the case.

This is the trend I see with most heavy blaster pistols in a combination of the following:

Higher base damage

Higher cost

Higher encumbrance

More negative specials

Having a look at my index:

• Encumbrance; light blaster pistols universally have an encumbrance rating of 1, heavy blaster pistols usually have 2 although many have 3.
• Base damage; light blaster pistols have a base damage of 5 or 6, heavy blaster pistols have a base damage of 7 or 8 (although one example has 6).
• Cost is highly variable across both, although many heavy blaster pistols trend to be more expensive with an (R) restricted rating attached to them far more frequently.
• Light blaster pistols do not have Pierce quality. Heavy blaster pistols frequently have the Pierce and Vicious qualities. Both usually have the Stun setting quality. Both carry the Accurate quality with similar frequency. Auto-fire is equally as frequent.
• Range bands don't seem particularly different, both having Short and Medium at a similar frequency.
• Heavy blaster pistols are the only Ranged (Light) weapons to have the Linked quality.
• Heavy blaster pistols are more likely to have negative side effects when rolling threat.
• Light blaster pistols are more likely to have a benefit to concealment when being searched.