I've been having a hard time killing deathclaws. I understand that they are meant to be tough but this is just ridiculous. I'm level 30 and I have an anti material rifle. I've tried every type of ammo but the only thing that can drop them quickly is a sneak attack critical. Please tell me there is a way to kill these guys in a timely fashion before they tear me a new one.
First, what difficulty are you on? Second, do you have a companion (or companions)?
I had the toughest time with Deathclaws, even with the AMR, but it's become easier. I'm currently traveling with Boone and ED-E, and that gives me a great opportunity with regard to sniping. And if the Claws get really close, you'll have help in fighting them.
Next, if you're using VATS to snipe, don't. I've been pretty much limited to one shot on VATS with the AMR from a distance. Sometimes I don't even get that. Lately, if I can see them in the distance (and I'm talking a good distance), I kneel down and get stable, and go to town. From that distance, I can land enough hits to get the kill. Don't remember what my guns or strength is, but both are pretty high up there. Before that, I did notice reduced efficiency from the AMR.
I'm not sure which ammo works best, with regard to hollow point or armor piercing. You'll have to experiment with that.
Currently, I'm actually not even using the AMR. I'm using the Gobi Sniper rifle that you can find in the Sniper Nest location. I engage from a pretty long distance, and even with .308 AP ammo, I was able to take out all but two of the Deathclaws at the Gypsum train yard (at least 7 or 8 kills). The other two I couldn't see till I got closer to the area, and even then, I was able to take them out easily. For those guys, I used VATS a few times.
Finally, if all else fails and they get close, backpedal while firing your weapon. Probably won't save you, but worth a try. Also probably will want to load up on chems, food and stimpaks and the sort. As you get low on health, just try and fill up during combat.
Oh, and try to do it stealthily. If you can kill them one at a time, from a distance, and while hidden, you'll greatly improve your shot at survival. Engaging multiple deathclaws at a close distance is suicide. Not sure anybody's making it out of that alive.