I have an older Colt HBAR that has the off size (can't remember if it is larger or smaller) holes for the LPK pins. Nice rifle, highly accurate but kinda annoying to say the least that it isn't totally compatible with my other AR-15 parts.
Hey, I have one of those too. I used it when we were at Atterbury. It has large pins and a steel sear/safety block. With some work & a Dremel you can get the block out. Then you can use the RRA 2 stage NM large pin trigger kit.
I hear Geissele also make a large pin kit. I don't know if it fits around that sear/safety block.