Bullet Travel

Bullet Travel is part of Harsh Realism for Tactical Shooters on page 32 of GURPS Tactical Shooting
It involves the idea that it could take more than 1 second for a bullet to hit at target within it's Max.
not to be confused with Bullet Time which is a GURPS Martial Arts concept for speedsters.
The rough "arrival time" guides of yards/250 seconds for pistols and yards/600 seconds for rifles imply a speed of 250 y/s (750fps) for pistols and 600 y/s (1800fps) for rifles. 
This obviously is not universally realistic: there are CO2 (non-powder) pistols which can only get up to 580fps for example, or spring-propelled BB pistols which only get up to 260fps. laws are often tailored regarding the fps ammunition is able to reach.
A wider range of rules might somehow be derived by using ammo weight and the damage inflicted by the attack: higher damage or lower weight should require higher speeds, while less damage or higher weight should result in lower speeds. No known attempt has been made to formalize such an idea.
This mostly applies to kinetic attacks: such a principle (mass x velocity) might not work for energy attacks. That or maybe it's so near-zero mass that it's near-infinite speed (light speed). Complexities can occur here if using Crushing (carrier) + Burning (followup) or Burning (carrier) + Crushing (followup) combinations: generally the former (fire in a bottle) is a lot more realistic than the latter (fireball summons an anvil).
In terms of designing Innate Attack to emulate guns, higher weight is mostly offsets: it's not just more to carry around for your Fast Reload but also means your attacks should take longer to get to their destination. The only possible downside is that heavier slugs left in an opponent (or cannonballs left on their boat, if you parry them before they can hit the deck at full velocity) are encumbrance until excavated. Generally "weight I need to carry around to use my attack" is a bigger drawback than "weight my opponent carries around until my ammo falls off him" though.
Bullet travel is an interesting consideration for Power Parry using an Explosion or Area Effect (including Wall) since it doesn't just involve the idea of ranged target as usual via B550's Size and Speed/Range Table (hard enough on it's own) but also if it's even possible to intercede an attack at a given distance.
For example: if two mutants with Burning Attack (fire -10%) throw explosive fireballs traveling at rifle speeds, and have Increased Range extending the usual 100 to 3000, then it should take 5 seconds for their fireballs to reach each other. This should mean that if one throws a fireball in reaction to the other, they probably can't cause that explosion to happen any closer than midway (1500 yards) due to the travel times.
Realistically it's probably going to be even closer to the defender due to delays in reaction speed. Exceptions might be made for those with precognition since in theory you could initiate your power parry prior to the actual attack, knowing the path it'll arrive on. That could actually change whether or not they attack (or where/when they choose to) though. The future seen by precogs isn't fixed if your changes influence the reactions of others.
In a situation where a Power Parry has fireballs travelling 600y/s and is defending against a 60y/s fireball (10% speed) he could probably cause the double-explosion to occur closer than halfway to the attacker, while a 60y/s parrier of a 600y/s fireball couldn't even meet it halfway: he'll probably get caught in the blast radius.
category:rules