Recently finished building a LR-308 and when I took it out, it would light strike the Remington Core-Lokt ammo not firing it.  My 450 Bushmaster has the same problem with the Remington ammo so I'm wondering if it's just the ammo or is something going on with the BCG?

Hammer spring, firing pin protrusion, headspace clearance.

I’ll check all three today. New JT Tactical drop in Sabre trigger but normal AR buffer and spring

So I was mixing apples with oranges when I posted this. I have two AR’s that are giving me trouble and I got them mixed up. The 308 won’t eject the casing but it hangs in the bolt at about a 30 degree angle. Looks like it is catching on the extractor and not releasing

The rifle where the casing is hanging on the extractor...I would first check the extractor for burrs, and inspect the ejector to insure that it is operating properly.  Checking the ejector is easy...put a casing under the extractor, and when you let go of the casing, the ejector should toss it out from under the extractor.  The extractor should not have burrs on it and should hold the casing when the case is pointing as if it were in the bore, but release the casing once the case mouth clears the rear of the chamber.

Check the inside of the bolt just ahead of the ejector area to make sure there isn't a rough spot that would create drag on the case as the ejector is trying to push the casing out of the recess in the bolt face.  Perhaps your extractor is putting excessive pressure on the extractor rim and is pressing it onto the opposite side of the bolt..  If the groove in the extractor isn't deep enough, or if the extractor is putting too much pressure on the extractor rim to the opposite side of the bolt, it could be causing the issue.

Finally figured it out. It was that Remington Core-Lokt ammo. Ran some Federal through it and it works great. My 450 BM has similar problems with the Remington ammo

The trigger should have enough energy to ignite the #34 primers of M80 ball. Either Remington got even harder/less sensitive primers, or.... how far below flush with the headstamp are they?

So now I don’t think it’s the ammo. Took it out with federal ammo and it would attempt to feed a round but the previous casing would stovepipe backwards jamming the bcg. I wish I would have taken pictures but I’ll do a drawing if anyone needs one. Also using a Bear Creek bcg which the guys over at 458 say is junk. Just ordered a new one from Aerospace Arms