Duders i'm stuck ! I'm about 24 hours in and doing the quest "oh papa" where you must talk to Melissa to convince the Great Khans to join the NCR. The only problem is that there is a quarry full of deathclaws between me and melissa and i'm finding it impossible to defeat them

I'm a level 19 and wearing the mercenary armor. Been trying all different kinds of weapons all the way to the minigun but their shields are impenetrable. There's too many of them and its really bumming me out

Please Help !

i used a stealthboy and move during the night otherwise F going pass all those crazies

Can you take a different route?  Like the dude at sloan says, can you go around a different way? (North?) 
 
If not, I would advise using a sniper rifle such as the anti-material rifle or the Gobi campaign sniper and crouching, sneak attack critical-ing the fuckers.  Take Boone along for the ride, he'll help out.

I just noticed Sparky_Buzzsaw is having the exact same problem. 
 
A stealth boy does sound like a really good idea, though I've never once used one of those things. I used to keep a collection of them in my fridge in Fallout 3.

  @Yanngc33: I had the same problem because I kept pulling 3-4 Deathclaws at once, and my companions would get raped fast and I'd go pretty soon after.
 
I finally completed that quest by just sneaking slowly, and pulling the Deathclaws one by one. I think the most I pulled at once was two — still more manageable than fucking four.
 
In terms of weapons, don't focus on DPS. Look for weapons with high pure damage as that's what important for breaking enemy damage thresholds.

A) Stealth Boy your way to her.
B) Since you got that quest I assume you can approach the quarry from "the other side", IE the north? Just take that route.
C) Snipe ( Gobi Campaign Scout Rifle) the Deathclaws from far, far away. Having Boone with you as companion helps a lot with that, since he's a sniper as well.
D) Complete " The Legend of the Star"-quest, which gives you an awesome unique laser pistol called Pew Pew. Deathclaws hate it, especially sneaky crits with it which often results in one-shot kills.

From what I've heard the best strategy is t- Oh my God OP, there is a Deathclaw behind you right now!

Gonna have trouble if you don't have anything that'll punch through their armour. The anti-matter gun is ideal, and fairly easy to get if you're lockpick and science are up to scratch, but plasma rifles and other high-power energy weapons work too (which funnily enough are harder to come by early on...). You can also set frag mines in their path, if you've bothered leveling explosives it'll cripple some limbs and make them slightly less scary, as well as doing more damage than any conventional weapons will... Who am I kidding, nobody levels explosives.

Just use mines. Once you cripple a Deathclaws legs, they become basically harmless. You can backpedal and kill them with ease.

I was going to mention frag mines, but seems people beat me to it. Just lay down a path of frag mines, shoot your intended target and then run in the opposite direction. Used indoors, you can kill a whole ton of dudes without ever firing a shot.   Explosives > Guns

There is a side-pass in the north-west part of the quarry that you can take to avoid the deathclaws.

Well people already mentioned everything I was going to suggest :P 
(sniping from stealth is really the easiest way)
 
So I'll just say that minigun vs. Deathclaws is a bad idea, they have a decent Damage Threshold and minigun does very little damage per bullet so they will easily shrug it off. You would need AP bullets against them, that's the only way a minigun would work; and minigun shooting AP bullets can get expensive :P
 
Also get yourself some better armor Mercenary gear is not even armor it is just clothes and offers very little protection, virtually anything is better.
That said armor does not really matter vs. Deathclaws since it is advisable to never let them reach you in the first place, as they will shred anything but the toughest of armors.
 

I'm looking forward to killing them with melee on my next play through.

I just cleaned out the quarry on very hard so heres what I did. I blew half my cash at the gun runners and bought the Anti materiel rifle. NOTHING works against those monster except this and even then it just does enough damage to them and break through their damage threshold like tennmuerti  .Your armor doesn't even matter since they'll just one hit kill you if they get close enough. I brought Boone for his headshotiness and ED-E for maximum perception to tell where they all are. 
 
I went from the south entrance near the miner town and sneaked shot the first couple of Deathclaws. You have to be far enough so that you only aggro one at a time. You HAVE to kill them before they reach you there is no other option. Aim center mass but try for headshot if you can since it takes away about 1/4 of health.Slowly make your way to the large green mining structure in the middle and go up the ramp to the top. To the north you can see the deathclaw alpha and to the east of it the deathclaw mother. 
 
From this point it's just pure attrition cause after blowing through those two I had over 60 Armor piercing rounds. At the end I had none and 75% was blown on the mother. 
 
Regarding why the Anit mat rifle no other weapon comes close to the needed damage to take them out on this difficulty. I tried miniguns laser miniguns shotguns pistols plasma weapons, and even a gauss rifle wasn't enough. On a headshot it only did 2 bars worth of damage and you had to reload on every shot that thing was a death trap. In short Screw deathclaws and screw very hardmode but at least I leveled up I guess.

If you a melee fighter scrap heap is your friend! Kills death claws in 1 hit! The mother and alpha I just planted C4/mines and pulled them in a cripple leg = easy picking

I haven't tried this myself yet, but supposedly Deathclaws can be knocked out with a couple of bean bag shots from a shotgun.  Then you can finish them off (or let a companion do it) while they're down.

Get the Anti-Materiel gun from Gun Runners and snipe them. Buy all of the ammo for that gun you'll probably need it unless you're a really good shot.

I'm only level 8 or so and Cheesus! They've made Deathclaws deadly this time. In Fallout 3 by the time I had my guns skill up to a certain level I would sneak attack my way past them like they were butter.

 
This is great though, it's an actual challenge this time. I enjoy putting down a bunch of mines, you know those ones you never use/pick up/buy. Pile them up and lure a Deathclaw. At the very least their legs get crippled making the job... a little easier. A little.

Deathclaws are savage. Boone + ED-E, an Anti-Materiel Rifle with armor piercing shots and a nice, high vantage point is your best bet. 
 
You could always turn down the difficulty if it's keeping you from advancing and then crank it back up.

" @Yanngc33 if ur playing PC just download the smokers armour mod, u get this sick assault rifle that does 150 damage and a grenade launcher that destroys deathclaws with one shot..also u get books that up all ur skills(science, lockpick, guns, etc) to 100...u also carry 100,000 in weight instead of 260 and u get 20,000 bottle caps and 65,000 pins...shits fun! "

@artofwar420 --- There's no cheese on the rocks so you're good. ( Am I stupid or sarcastic? You decide. I choose both.)