I've seen a few posts regarding 6.5 Grendel feeding issues, and it's either a different type of feeding issue, or I have no clue what the posters are saying. I have just started building my own rifles, and am a certified newbie. I upgraded my wife's .223 Wylde (and a few other rifles I have) numerous times, and my first build was an AR in 300 Blackout. Once completed, I was amazed at how well my Blackout performed, and haven't had a single problem with it. My 2nd full build was done in 6.5 Grendel. I just took it to the range for the first time, and ran right into trouble. Everything worked fine on the first shot, but I cannot get the follow-up round to cycle...at all. The second round will not get fully chambered, I'll get stovepipes, etc. I'll clear the rifle, charge it again, fire the shot, and that's it...back to clearing it, reloading, and on, and on. I had a similar problem with the .223, and just needed to replace the buffer spring and all was well, but since everything on the Grendel is brand new, it's definitely not a worn out buffer spring. I have read tons of posts regarding this caliber and the proper spring to use, and I get just as many differing opinions and answers. After reading through many posts here, I'm starting to wonder if it's even the buffer spring that's the problem. I am using a BCA 6.5 Grendel upper (20", right side charging), and I installed a simple Anderson AR-15 Mil-Spec Buffer Tube Kit. I've had very few problems with any of my firearms in the past, and am not sure how to even troubleshoot the AR. Since the Anderson spring I'm using now is the minimum I could even use, my guess is to get a better spring? What else could be the problem? The magazines are brand new. I am shooting 123 gr BTHP Hornady Black ammunition. Is the buffer spring usually the problem, or am I way off on this one? Funny how something so simple has gotten me so dumbfounded. Any help, advice or recommendations anyone has would be greatly appreciated.