Does APDS or AV ammunition fare any better against materialized spirits (or, for that matter, any critter with Immunity (Normal Weapons) power)? Does it halve their Immunity like it halves armor?

pg. 264, SR3:
"APDS, AVM, and other armor-piercing ammunition are treated as normal ammunition against creatures with this power."

As one of our GM's says, "Nice try, though".

Thanks for the reference.

We play it as no, since the "armor" isn't a phyiscal composite, like in a vest, but spiritual the bug doesn't care if it's getting hit with soft lead or tephlon coated slugs.

Against actual, real, non-spirit animals , not magical spirits, like the enhanced armadillo, they do work.

They just have hardened armour, different from the immunity to normal weapons - the only time they can get immunity to normal weapons is if they're possessed, or inhabited by great forms, or contain hidden life. Combine the two and you have a very scary monster indeed... *Possessed Jugernaut goes into list of evil opponents*