This sounds like a very interesting mutator. My guess would be that it's very much playable with normal chess.
(I would like to point out that there are a couple of typos while listing the numbers. 2 and 12 both deflect to the right.)
An interesting variant would be for the bullet to be deflected 180° (return to the shooter) when the dice add up to 7 (or any other number.) This would make someone think twice before shooting a bullet.
(Might be wrong), the chances for the dice to show a certain number are:
2 : 1/36
3 : 2/36 = 1/18
4 : 3/36 = 1/12
5 : 4/36 = 1/9
6 : 5/36
7 : 6/36 = 1/6
8 : 5/36
9 : 4/36 = 1/9
10: 3/36 = 1/12
11: 2/36 = 1/18
12: 1/36