Again, Caesar has 300 million on his head, and bounty is (apparently) a good indicator how powerful a pirate is:
- Luffy compared Hody's toughness with a 200 million pirate (this alone basically confirms it)
- Caesar decided that the Yeti Cool Brothers were enough to handle the Straw Hats, judging by their old bounty only. In the end he admitted that they couldn't do anything against Law and Luffy.
- Monet realized that there is no way she could defeat a 400 or 120 million bounty pirate (and she was right).
So, unless Oda states that CC only got such a high bounty due to his horrible experiments (an exception like Robin, Caribou or pre-TS Kidd etc.) we simply have to accept that this mad scientist is strong enough to take a few hits from Luffy. He is worthy of his 300 million.
But anyway, people made me curious so I checked just how many attacks he soaked up to this point:
First encounter in front of the lab (671)
! ![](http://s7.directupload.net/images/121202/bqtb6nrj.jpg)
One Jet Mace to the face, impossible to tell if Luffy used hardening or not. His gloves are black and he didn't say hardening - Jet mace! However, he also used a (failed) hardened Gomo Gomu Bell without adding "hardening". So I assume that from then on, his attack is infused with armament haki.
Next came a Jet Stamp to the torso
! ![](http://s14.directupload.net/images/121202/vl8ve5bi.jpg)
This was all at this point (671). He got merely 2 attacks in before Caesar ended the fight with his Empty World move.
Now 10 chapters (!!) pass till they meet again (680).
Judging by Caesar's face, he had time to recover from 2 of Luffy's weaker attacks (Stamp and Mace are standard stuff ever since). Only Usopp, Brownbeard and Nami faced him during that time. In Street Fighter language: New round, Caesar's lifebar is back to 100%.
Luffy opens the fight with an unnamed move, probably just a very fast hardened punch (Caesar didn't even see it coming)
! ![](http://s14.directupload.net/images/121202/ck3jb5d8.jpg)
Next comes another standard move, a Jet Pistol that isn't even hardened
! ![](http://s14.directupload.net/images/121202/kogkr3pl.jpg)
That was it! Monet interfers, stops his hardended Jet Gatling and traps him in the trash room
Another 9 chapters pass till their next meeting.
Judging by Caesar's face (again), he had plenty time to revocer from 2 of Luffy's absolute standard moves. Round 3, lifebar is back to 100%. This time Luffy is serious and opens with a mighty Elephant gun.
! ![](http://s7.directupload.net/images/121202/brttz9zo.jpg)
And it only grazed him. Enough to make him shit his pants, but it did next to no damage (he is nosebleeding, a small scratch on his cheek).
Next is another standard punch to his face, hardened.
! ![](http://s14.directupload.net/images/121202/4c8o2grv.jpg)
Followed by another standard punch in the chapter after.
! ![](http://s14.directupload.net/images/121202/z5meuijm.jpg)
So we have
- 1 Hardened Jet Mace
- 1 Hardened Jet Stamp
- 1 Hardened standard punch
- 1 Normal Jet Pistol
- 1 Elephant gun that didn't really connect (so it's basically out of the picture)
- 1 Hardened standard punch
- 1 Hardened standard punch
Means Caesar took 7 attacks in total, he had time to recover from 4, one had next to no effect. Leaves the last 2 standard moves, which fully connect and do some good damage, considering that they are nothing extraordinary.
Now Luffy didn't even use any of his strong named moves, so I see no problem with a 300 million guy not being oneshotted by his baseline stuff.