Are B rank Bullets ranked at a certain level or +2s? I just wanna make sure I understand for rping.
For instance my gunslinging Mastery is 61. So I find 61 on the dpr chart and add 2?
Correct, if your gunslinging mastery is in the 61-80 range, and you fire a B-rank bullet, you go like this:
DPR: 61-80: 2. Small Building Level + B:+2 =
4. City Block Level
Now, if you added Haki to your bullet, it'd go +1 (invisible Haki) or +2 (black Haki), depending on which you opted to use.
So then it could look like this:
DPR: 61-80: 2. Small Building Level + B:+2 + COA: +2 =
6. City Level
Now say your target had 61 durability, you go to the durability scale, and you see this:
61-80: 4. City Block Level
Now, he could block the bullet with his hand for example, and imbue his hand with black COA, so his durability would be this:
Durability: 61-80: 4. City Block Level + COA: +2 =
6. City Level
Now you compare the DPR to the durability, and you check this scale:
DPR 2 or more below dura: Not very effective
DPR 1 below dura: somewhat effective
DPR equal to dura: normal damage
DPR 1 higher than dura: quite effective
DPR 2 or more higher than dura: super effective
In this case, DPR is equal to durability, so normal damage. Then it's up to you to interpret what normal damage would be in this case. My interpretation would be that the bullet would pierce into his hand.
''Not very effective'' would be that he can actually block the bullet completely and only a trinkle of blood appears. ''Somewhat effective'' would be that he still stops the bullet, but his hand has a bit more damage. ''Normal damage'' would be the bullet piercing his hand, but that's it. ''Quite effective'' would be that the bullet pierces his hand and still hits him in the chest as well, but doesn't go too deep. ''Super effective'' would be that the bullets blows right through his hand AND chest.
Then you just have to sort of RP your damage affecting you based on your stamina. Someone with 101+ stamina could probably continue with a hole in his chest without much trouble, like Whitebeard did in Marinford. Someone with less vitality will have to show more trouble and exhaustion, maybe some blurry eyes, etc..
There are some other ways to get +s on your DPR / durability, such as advcanced conqueror's Haki (+1 to DPR), Tekkai (+20 to your durability stat when in use, which in turn should put you up 1 or 2 tiers).
This should explain well enough how the overall DPR system works. It's a lot in the beginning but it gets super easy, you know your masteries by heart and then you just add it up. Takes about 30 seconds for me.