I'm new to the Grendel. I just bought a Specialized Dynamics 20" .264 LBC upper. I was led to the LBC because I was told it would shoot both Grendel and 264 ammo. Anyway... I bought some Wolf and Hornady ammo from Alexander Arms. The upper functioned fine, shot all the Hornady ammo fine with descent accuracy but 2 to 3 rounds per box of the Wolf would not fire. They had light primer marks. I didn't think too much about it thinking it's just the Wolf ammo. Moving on I bought some AA brass (Lapua) and loaded some 120g SMK's. They won't fire just like the Wolf. I took some measurements with a comparator gauge and the Wolf and AA brass is shorter than the Hornady and much shorter than the fired brass. So, here's the question. Is my chamber cut wrong and is there any way to correct it? On a side note, the accuracy with once fired brass is much better than new ammo. Best preforming is 28g Vit 140, 120g SMK's in the Hornady brass with shoulders bumped back .002. Thanks for reading and any help is appreciated.