I have been slaving away trying to find a Battlemaster I like and I think I have a solid build with this one:
BLR-1G(P), XL 340, 2 x AC/5 (4 tons ammo), 2 x PPC, 5 x MLas, 14 DHS, Endo, 496 armor.
I have my AC/5s bound to left mouse and the PPCs in chain fire on the right mouse. I have been hitting both mouse buttons at the same time (2xAC/5 + 1xPPC) which dishes out 20 pts. damage. You can fire like this every 2 seconds at really nice range. Get a heat warning? Just run the AC5s which at 6.66dps is pretty good sustained dps.
The 5 medium lasers are for when the battle moves in close or as a light swatter. I have had a number of opponents try to move in close to me to avoid the PPCs only to be surprised by a burst of 5 x MLas which, at closer range with a target rushing at you is pretty easy to hit an enemy with.
Not a perfect build but it seems to be a decent compromise between ranged combat and close combat so it is flexible. The XL engines allow you to move a little so you are not so easy to ambush.