A lot of pent up anger coming out. I think it is mostly frustration at not being able to avenge his four workers' death at the booze warehouse. He's losing face in the community and he was told (by Nucky) to "be patient".

Also, it doesn't help that his own family seems to make fun of his lack of education. Chalky has NOT forgotten from whence he came but his family apparently have (forgotten).

It's (IMO) one of the better story lines.