The Techmarine in my Kill-Team can soak 38 wounds in his chest. Other body parts vary due to cybernetics and armor histories, but I have to nail him with high-penetration, high-damage weapons to actually hurt him. Amusingly, he's the member of the party who's hit critical damage most often. That said, I prefer the errata weapons.

Gaire said:

^^ this

I've never found it hard to hurt my players, the trouble I truly find is finding weapons that tread the fine line of hurting without sending to critical. The higher the dice cound, the higher the chance for RF and the less predictable they are and the more likely I'll do zero or 100.

Hrm. I mostly hurt them with Hordes (tend to drop into crits fast) or things like Battlesuits. They're about to be fighting some Rubric Marines and a sorcerer, so that should be an interesting look at them taking Astartes-grade weapons fire.

Kshatriya said:

When the PCs get smart and use cover and squad mode abilities it gets even harder to hurt them. If they have a librarian with force dome you have to use the heavy guns to scratch them, or use alternate means.

In general though standard Astartes bolt weapons will scratch or do nothing to mid level Marines- 1d10+9 pen 4 is just not enough to punch through armor and toughness. Give them special gear and squad mode abilities and your PCs will have a considerably tougher time dealing with them.

Then again, keeping the balance of scratches and not sending them to critical is still the challenge.