Anyway. I don't worry too much about DF vanilla ranged weapons since 40.05, although I would like that black powder mod by DC to be updated to reflect the new momenta values.
You're not thinking of mine, are you? Because I've just about got it fine-tuned to the point of being ready to release... ish. Armour still has an annoying habit of deflecting lead bullets without the wearer suffering so much as a bruise, so I'm going to take onboard some of the excellent advice in this thread and see if upping the mass of the individual projectile helps at all.
You may not need to increase the mass of the projectiles. There are two reasons why deflection can occur:
1) The momentum of the bullet is too low to penetrate the armor. Increase [SHOOT_MAXVEL] and/or [SHOOT_FORCE] to make sure the bullet momentum is high enough. For testing, just make them super huge (say 100,000) to make sure you don't see any deflections.
2) The bullet itself cannot withstand the momentum of impact. See the heading "The Projectile Absorbs the Force of the Collision" on the
Material Science page of the wiki. I believe this mechanism is unchanged in the new version, although I have not tested it carefully. If this is the problem, you have a few options:
a) decrease the projectile contact area (gets multiplied times armor thickness (15-30) and rounded to the nearest 100, so only helps if it is not already less than 10).
b) increase the projectile size (and hence mass)
c) increase the IMPACT_YIELD for lead.
The IMPACT_YIELD for lead is pretty low (only 35,000, compared to 10,000 for wood, which is known to have this problem and 245000 for copper, the softest weapons grade metal). I bet you already made your guns pretty powerful by increasing force and max velocity, so I am guessing your problem is #2. I am also guessing that your contact area for bullets is no more than 10, so decreasing that won't help either due to rounding. So you can either increase your bullet size (and mass), or, if your bullets are already as heavy as you want, just increase the IMPACT_YIELD of lead.
I believe this mechanism is supposed to represent bolts being destroyed when they hit armor. This works well for things like wood or bone, which will shatter, but lead bullets are expected to melt on contact. The momentum of the somewhat melted lead is so high that it still will penetrate (thin) armor. I would just increase the impact yield of lead by a factor or 10 or so to make this issue go away, as a lead bullet is not ever going to shatter. Also, I doubt lead is used in any other weapons or armor besides bullets, so increasing its impact yield won't affect anything else.
If you don't like doing this, you could also just make your bullets out of copper or silver. You could even make this a "feature" - by setting the SHOOT_FORCE of your guns very high but the SHOOT_MAXVEL to something moderate such that all bullets are fired with the same velocity, you could make copper/silver bullets armor piercing and lead deflected by armor but more damaging to unarmored targets due to its larger mass.
If you have questions about exactly what numbers you will need for your IMPACT_YIELD, SHOOT_FORCE, SHOOT_MAXVEL, etc, I should be able to estimate these fairly accurately if you post the raws for your bullets (specifically size and contact area), and any modded armors that you want to protect from and/or be penetrated by bullets.