There is no need to stop coming here. We want to know information that fixes problems. That is what this forum does well. Not all problems are the same and need the same fix. If you have a problem or solution that hasn't been discussed, it helps us to know how to fix the next time this occurs.
Be sure to include the inside depth of the buffer tube. That is a key to the recoil system functioning properly since you should be good on the spring and buffer.
Welcome to the forum.
Is this the rifle he purchased?
https://www.stagarms.com/stag-10l-308-m-lok/#ProductSpecsDetail
How many rounds through it? Have you tried any other ammo besides your reloads?
Can you post a picture of the bolt face with the extractor?
Those questions should get the information started until someone who knows more than I do comes along to help.
The buffer tube looks like it could be screwed in one more turn. It is barely hanging on to the retainer pin. That, along with a buffer tube that is longer than 7 inches internal depth, can contribute to the issue that you appear to be having.
I addition to what @jtallen83 said,
Will it hand cycle ammo?
Will it hold open on an empty mag with hand cycling?
What is the internal depth of the buffer tube?
@98Z5V what did you do to piss off the Air Force this time?
They say it is an accident. I figure they were aiming for you but missed.
https://www.nbcnews.com/news/us-news/air-force-jet-accidentally-fires-rocket-arizona-desert-n1050571