Here's what my tactic was in the quarry. I had Lily and ED-E with me, and I'm not in hardcoe mode, so they won't die. I was at 100 in Energy Weapons and Guns. I would sneak from far away, and fire my Marksman Carbine with Armor piercing rounds, so as to attract one Deathclaw at a time. This worked for a while. I would shoot it as it ran down the ledge, Lilly would intercept and do what she could, then it would kill ED-E, and by this time I have my special Plasma Rifle (forget the name) and I'm unloading on the bastard. (And plasma, apparently, is no good against the super skin they have, either.)
Then I snuck deeper into the quarry. I saw the Alpha Male, so I did the sneaking lure trick. Suddenly every Deathclaw in the area comes down upon me at once, killing Lily within a single swing of her sword and ED-E got swatted down like a fly. And here I am with an army of the two alphas and two or three more Deathclaws besides hitting me over and over at high speeds, killing me almost instantly.
I even went back to Very Easy just to get trough this, to no avail. I used Med-X, Psycho, you name it. What am I doing wrong? Is there a trick? Or are the Deathclaws just plain broken now? And why can't armor piercing rounds beat the damage treshold of bare skin? Bullets go through alligators like butter, so I don't think Deathclaws should have super skin. Or if they should, how can they move like cheetahs on Jet!?