New Upper Build Locking Up After Firing

[Red*Lion]

I would remove the bolt, cam pin and firing pin. With the charging handle in place I’d slide the bolt carrier into the upper receiver. If the carrier is not binding in the upper I’d look closely at the bolt for any wear marks or gouges. If there are no unusual marks on the bolt I’d try putting just the bolt into the barrel extension with no carrier. The bolt should easily fit into the barrel extension. See if there is much resistance in rotating the bolt in the barrel extension. If the bolt isn’t binding in the barrel extension then I’d check to ensure the mag is not interfering with the carrier.

If everything looks ok it sounds like you are not getting enough gas. You could try to open the gas block completely to see if the spent casing ejects. Look at the spent brass and make sure it looks ok. Some times a rough chamber will show up on the brass. Your using quality components so unless you have a rough chamber the only other component is the buffer spring and buffer.

I’d measure the buffer spring and weigh the buffer. Make sure you are either using carbine buffer tube with carbine buffer and spring. If using a rifle buffer tube use a rifle length spring and rifle buffer.

One other thing to check is the cam pin is not out of spec, moves properly and has no unusual wear marks.

I did as you suggested. The carrier slides freely with no binding. The actual bolt does not appear to have any marks. The bolt inserts easily into the barrel extension and can be rotated easily.
As far as the magazine goes (10 round ASC), it seems to feed as expected when manually cycling rounds. Same as a typical well functioning mag would.
I inspected the last round that I shot and it does not appear to have any abnormal marks. 3 pics from all angles below.

[ATTACH=CONFIG]16400[/ATTACH] [ATTACH=CONFIG]16401[/ATTACH] [ATTACH=CONFIG]16402[/ATTACH]

The lower used has a Luther rifle stock with rifle buffer and rifle length buffer spring. My 18" criterion barrel also uses a rifle length gas system.

I will mention that the JP bolt that I used in a Toolcraft carrier, does move very loosely/freely if that makes any difference.
I am going to try to make try a shot with a different charging handle (another BCM gunfighter handle) and use the Toolcraft bolt with the Toolcraft carrier. I will also open up the gas all of the way as well.