Requesting help solving 10.5 reliability

[FlyingHunter]

My first SBR is a Noveske 10.5 in 6.8spc. It sits on a Colt registered lower. The lower fed the 6.8spc fine, in fact 100% on a PRI 16 inch upper. The 10.5 had numerous FTF and I sent it to Noveske. They promptly tested it and found no issues and returned it. The case gets dented in 2 places and often requires a mortar technique to extract. The lower has a shorty ACE stock with the replacement spring and short internal buffer tube. I put the Noveske 10.5 upper on another Colt lower set up as a DMR with the standard buffer tube, spring, and weight. IT feed fine and did not dent the cases and I thought - problem solved! So I promptly dug out the original buffer tube, spring, weight for my SBR and put a standard A2 stock on. Went to test fire and proud of my detective work and was rewarded with FTF - the bolt would not close all the way. I think 2 things: One, the spring/buffer/tube is a probable source of the issue Two, I need your advice. In advance, thank you.

[ginarik]

I has a similar problem with what ur going through. I have a 7.5" Noveske in 5.56 though.

Have u tried different brands of ammo? XM193 ammo works like a champ in mine with no problems at all. Once I started using reloaded ammo and Wolf, it started to FtF. I ended up borrowing a friends bolt carrier to see if his worked in mine and it did. The culprit was the gas key not having a good seal. I ended up buying a new gas key and a heavier buffer (H2). Now everything (.223, 5.56, reloads and Wolf) works in my rifle.

Even though we both have different calibers, the gas system is still the same theory.

I hope this helps!