The attack momentum formula used is from this thread. It was written in v0.40, but it's probably still true in v0.44.
Projectile_velocity = ( SHOOT_FORCE / Weight ) / 20 , capped at the SHOOT_MAXVEL and rounding down
momentum = velocity * weight
The overperforming wiffle shot mentioned in the OP was MAXVEL 100 and mass 0.0785 (When testing, I set FORCE to a million or something, just so it caps out at MAXVEL and gets removed as a factor)
Predicted momentum = 7.85
The armour formulae were pulled from the wiki pages for weapons/material science:
MomentumThreshold = (amrSY/wpnSY + (Area + 1) * amrSF/wpnSF) * (10 + 2 * amrQuality) / (Sharpness * wpnQuality)which in the arena simplifies to
MomentumThreshold = (amrSY/wpnSY + (Area+1) * amrSF/wpnSF) * (12)Given contact area = 10, armour = iron (Y/F = 155000/310000), weapon = 'plain' steel (Y/F = 292000/515000, just vanilla iron and steel averaged together out of pure laziness),
the predicted threshold works out to ~85.8
The wiki also gives a second (deflection) test, which is irrelevant here
2*wpnSize*wpnIY > Area * amrDensityAnd then a third (fracture) test, which can apparently override failure in the first:
MomentumThreshold = (2*amrIF - amrIY) * (2 + (0.4*amrQuality)) * AreaBut given the values above, this returns 39.06, which is still well above 7.85