I just had a very disappointing range session. I have an AR build, that had numerous failures to feed. I have a Spikes Tactical lower, with a Huldra 5.56 EvoSlank 14.5" upper. (This is a gas piston gun, not DI.) Not even 20 rds through the gun. I was shooting .223 Barnes 50 gr. Vor-TX ammo. Would not feed the next round, and failed to eject one case. I was using Magpul PMags. I checked the gas piston setting, it is set to it's regular setting. The buffer spring/tube are exactly what Spikes sold me, I've made no changes. Any suggestions as to what the problem is?