Let me start by saying I am not all that experienced in the AR platform. I own an AR-15 I assembled with a kit from PSA so I know enough to put the parts together, but not enough to troubleshoot every problem.
My son built .5mm Grendel from the ground up, no kit. We went out to the range yesterday so I could try my new TFO sights and he could test fire the Grendel.
Every round he shot got stuck in the chamber. I would call it a failure to extract. They were stuck so tight that you could not pull the charging handle back by hand. He had to bump the charging handle down on the table to get it to extract the spent case. Once they came out, the case looked pretty normal, no obvious scuffs or scratches. The portion of the neck where it tapers did look a little bulged compared to an unfired round.
If you cycle it by hand, it will extract and eject full rounds with no issue so clearly the cases are expanding and getting stuck.
What are the possible causes? What would you check first to try and solve this?
My son built .5mm Grendel from the ground up, no kit. We went out to the range yesterday so I could try my new TFO sights and he could test fire the Grendel.
Every round he shot got stuck in the chamber. I would call it a failure to extract. They were stuck so tight that you could not pull the charging handle back by hand. He had to bump the charging handle down on the table to get it to extract the spent case. Once they came out, the case looked pretty normal, no obvious scuffs or scratches. The portion of the neck where it tapers did look a little bulged compared to an unfired round.
If you cycle it by hand, it will extract and eject full rounds with no issue so clearly the cases are expanding and getting stuck.
What are the possible causes? What would you check first to try and solve this?