I recentally built a 300 acc upper and finally got to test it today. it is a 16" with a pistol length gas tube.The lower and bolt is an Olympic arms that has run flawlessally in 556 for years. Fit and from lower to upper is pretty good, verry little slop. I ran into an issue with it cycling, it will fire, grab the next round and feed it into the chamber, but the spent round will stove pipe behind the new round causing a malfunction. Looks like the new round begins to chamber when the case head of the spent round gets between the bolt and new round. The first box of 20 federal 150gr would literally turn it into a single shot, had to clear the spent case and advance the bolt on the live round in the chamber. the second box of Remington 125gr had the same issue but only 1 in 4 rounds, not every time.
So this leads me to believe that the ejector isn't slinging the case out of the action properly? could this be a weak spring? is the spent case dwelling in action area too long and getting caught up when the bolt is returning into battery, or is it bouncing back into the action? when it runs correctly the cases fly to the 2-3 o'clock position.
As always thanks for any input.
So this leads me to believe that the ejector isn't slinging the case out of the action properly? could this be a weak spring? is the spent case dwelling in action area too long and getting caught up when the bolt is returning into battery, or is it bouncing back into the action? when it runs correctly the cases fly to the 2-3 o'clock position.
As always thanks for any input.