I didn't have any issues with a canted gas block with my LPR, but I did suspect it to impact the inside of the handguard. I ended up pulling my barrel out and replacing it with a conventional barrel and gas block. I actually went through three gas blocks until I found one slim enough to not hit the rail. The first two I tried showed obvious fliers when I shot groups.
This is the factory gas block after I pulled the barrel. Looks like it was hitting the inside of the handguard.
View attachment 8789997View attachment 8790001
This is the inside of the rail. All you can really make out is gas leakage.
View attachment 8790002View attachment 8790003
When I pulled handgua I found this bur. I'm the upper receiver there's a ridge or alignment mark to mate with the groove inside the handguard but it looks like whoever assembled the upper caught the alignment ridge on the edge of the handguard and created the bur you see no sanded it down and didn't have any other issues.
View attachment 8790004
View attachment 8790005
I think the Proof barrel they use is kind of a dog. My gun came with a .8'something group but it was the biggest .8 group I ever saw. I think it said something like .824 but when I measured it I couldn't make it smaller than .880. but whatever, right? It was pretty inconsistent and that's why I pulled the barrel. With a new barrel, it's the best shooting AR I have.
Despite all this, I truly think they make the best upper receiver and handguard mating system made. At this point it's kind of an anomaly. If you got a rifle or upper, you got probably the best system out there. If LMT would make a 15" or 17" rail it would dethrone the LPR but if you want the best precision AR-15 upper/ receiver, this is it. It's definitely overpriced if you plan on stripping the parts out of it like I did, but I don't know where you could get a better builders kit. Money aside. They announced they were going to make a universal handguard..I think they're making new products and that's why you can't buy LPRs or builders kits anymore. I remain skeptical about a traditional handguard. It's a shame. It seems like they could've sold builders kits until the cows came home.