Toughness (natural or otherwise) doesn't affect Crippling at all.

Hellooo Crippling "Munitions".

Okay. I'll give a little bit of background.

We came across a space hulk and our transport crashed into it as it was pulled out of the immaterium. So in order to get us free, our regiment was assigned to get delivered in by boarding tubes and now we have to fight our way through hull ghasts and then eventually we come across the Kommandos. We outfox them, then we engage a large group of boyz, squigs and two mega-nobs.

We drive one nob off by taking his helmet out (forces him to retreat to where there's oxygen) and we manage to rip the other one with long las and plasma fire. The squig hampster bombs take out a few of our guys. We push in, trying to get to the reactor unit as we have to blow it up and set the hulk's peices apart and give our ship a chance to pull away.

We just killed the other nob, but about three more of our guys got slugga/choppa'd down. The PC's are all jacked up though. Most of us went through our fate points pretty fast.

yes our GM is using mob rules. Ork Boyz have impressive willpower when they're in large groups. Also 44% ballistic skill sounds about right, given they'll be in close range too, 55% sounds like what most of them have been rolling against (one of the nobs got 6 degrees of success once with his twin-linked heavy slugga, that was almost the end of the guy with our plasma gun).

All in all, Flame has been effective still (we have two flamers and we've been overlapping. About ten ork boyz dropped to it, but the other twenty were a bit of a problem), though the squigs keep dodging and the gretchens keep escaping before we can kill them when the boyz finally go down.

Ultimately, we're low on resources now, there's little to no cover in the hallways of this space hulk and we have no idea how many thousands of orks are here. Plus there's probably a **** wagh boss or something.