Penalties to ranged weapons (in General)

I know that bows are affected by the archery skill but what about crossbows and slings? Does anyone know what are the penalties to CTH for crossbows and slings in ranged rounds?

Why not test it with base slings/xbows?

Also, there is no archery in melee, thus the 40% penalty

I think this penalty thus is for all ranged weapons.

Archery doesn't affect xbows. Ranged penalties for xbows are unknown. See this changelog entry (which I believe is wrong):

# Archery is different: it no longer affects being able to fire during round 2 of ranged combat. Instead, it affects the ability to use a bow during all rounds -- without archery you will have about 20% of the chance-to-hit that you would have with maxed-out archery. Interpolation between these extremes is linear. (That is, 20% of both DX and non-DX based chance.)
# Bows (with maxed out archery) now have 90% base to-hit in the 3rd round of ranged combat, except the ELB which has 100% to-hit. Odds are still slightly lower in 1st and 2nd rounds.
# Penalties to ranged weapons used during melee combat have been adjusted. Slings have 80% penalty; xbows have 40% penalty. Bows are unchanged at 60% penalty.
# Slings and xbows also have slightly greater penalty to to-hit during 1st and 2nd rounds of ranged (but not 3rd round).