My friend just bought an ar and we were running wolf ammo through it today at the range. We had about 6 ftf's in 40 rounds. He was kind of guessing that it was a problem with the buffer tube weight or spring not being powerful enough to get the wolf ammo to clear the bolt and cycle into the chamber. Any ideas or similar issues? Ideas? He is currently looking for a new spring and weight if anyone has extras and are willing to trade or purchase.