How to Read Ballistics Results

The calculator doesn't just apply formulas — it runs a numerical simulation with air drag and Magnus lift. Knowing what each number means makes the results far more useful.

Muzzle energy (J)

Kinetic energy as the BB leaves the barrel (E = ½mv²). This is what field limits regulate, and it describes your gun's power independently of BB weight.

Max range vs effective range

• Max range: horizontal distance until the BB hits the ground. It's "how far the BB lands", not "how far you can hit".
• Effective range: the distance over which the trajectory stays within ±25 cm of the launch line — roughly how far you can aim at a torso-sized target without adjusting your point of aim.

Play with the hop-up slider and you'll notice something interesting: more hop keeps increasing max range, but once the BB starts climbing, effective range actually shrinks. That's why over-hopping loses fights in practice.

What the hop-up % means

100% is the "flat trajectory" reference where lift balances gravity mid-flight. 0% is no hop; around 150% is a slight over-hop where effective range often peaks.

Impact velocity / impact energy

Speed and energy remaining at the point of impact. Light BBs start fast but bleed energy quickly to drag. In the weight comparison table you'll see heavier BBs arrive with more energy despite identical muzzle energy.

Backspin (rpm)

Estimated spin rate corresponding to your hop setting. Heavier, slower BBs need more spin for the same lift.

Model limitations

• Wind (cross or head) is not modeled.
• Spin decay during flight is ignored (real spin fades gradually).
• BB quality variance and hop rubber condition can't be computed.

Read the results as "estimates under ideal conditions" — they are most accurate for relative comparisons (changing weight, adjusting hop) rather than absolute predictions.