X-Men Origins: Wolverine

Claw spin is the first special power which you obtain in the game, (quite near the beginning of the first chapter) and is initiated by holding 'RT' and pressing (or once upgraded) tapping 'X' for a prolonged period of spinning. Without any boosts to the rage gauge by mutagens you should be able to do at least 3 claw spins and if you target weaker enemies then you should fell them in a single use.

If you fail to get this by the end of the game (I myself only had like 184 or so) simply go to one of the starting levels and spin away, mutilating foes (which are so weak it's unbelievable) and before you know it you should be hearing that ring and see the icon in the bottom center of your screen.

I beat the game and did not get this achievement. So I found that the easiest and fastest way, is go to replay mission, and go to chapter 2 and go to checkpoint ambush. Theres plenty of guys in a small area when they get bunched up on ya press RT and X then start spinning and moving into the Enemies keep pressing x if you bought the upgrade to make it last longer, then when you kill all the guys you go to the top of the cliff side kill the three guys up there then jump down the other side and it saves rinse and repeat until you get the achievement.

the best way i found (in my opinion) is to replay chapter 2: roadblock
just ignore the helicopter at the start and run to the end where all enemies are. the more damage you take while running there, the better. after the first group you go through a building. that's a checkpoint and you can quit and replay again.

mutagen i can suggest to help deal more damage:
samurai: because i am still working on the combat reflex chievo... and chances are you too ;) never take this mutagen off.
art of war: to increase damage.
blood rage: this is a MUST because at the start of the level, before you reach the first group, you let the helicopter damage you until your red bar is gone and only your organs are left. by doing this you'll deal much more damage and will speed up the killing process a lot.

My way for doing this is the sentential boss battle as you get about 4 at a time with infinite re spawns, the enemy's are weaker then normal ones so can kill them with no hassle