If my memory is correct the Outlaws MC used to use bombs a lot. Especially when Taco Bowman was calling the shots.

The sicilians are known to use them in sicily but not here in the usa. Over here they would just shoot them in the head and stuff them into a car trunk like normal OC murders. Bombs are nasty to use...too much potential for unwanted collateral damage like those kids in the article JCB posted the link to.