Thanks for your reply. Yeah, I've seen a couple of varieties of the front cap. Right now I've got an aero precision M5 receiver and I've been trying to plan things out before I buy a bunch of parts randomly. I've seen a couple LR 308s or AR-10s online with the A1 front handguard, so it's obviously possible.
I'm putting together an LR308 / DPMS upper and I'm trying to find the triangular A1 style handguard. Plenty out there for AR-15, but not having any luck for an LR 308. Any suggestions?