You can color the bullet on a cartridge and put it in the chamber to see if the bullet is hitting the lands. If the bullet is not into the lands I'd try firing one round with an empty mag in the well. If your gas block is adjusted properly the bolt should lock open on the empty mag. If the round still fails to extract you may have an extractor issue if the gas block is adjusted properly. If the gas block is improperly adjusted with to much or to little gas you can have failure to extract. I start with a closed gas block then open the gas block a little and fire. I continue to fire one round opening the GB a little until the bolt locks open on an empty mag.
You should be able to load one factory round into the chamber and be able to extract the unfired cartridge without difficulty. If a factory round does not want to extract you could use a black marker to color the case to see if the shoulder is being jammed into the chamber. You could measure the bolt face depth of your 7.62X39 bolt an see if the face is .125 +or- .001.
You could have gotten an out of spec bolt.
A 6.5 Grendel bolt with .136 bolt face depth would give excessive head space on a barrel chambered for a X.39 bolt. I guess it is possible your barrel is improperly marked but you should be able to check the head space with your x39 bolt/barrel using go no go gauges.
You should be able to load one factory round into the chamber and be able to extract the unfired cartridge without difficulty. If a factory round does not want to extract you could use a black marker to color the case to see if the shoulder is being jammed into the chamber. You could measure the bolt face depth of your 7.62X39 bolt an see if the face is .125 +or- .001.
You could have gotten an out of spec bolt.
A 6.5 Grendel bolt with .136 bolt face depth would give excessive head space on a barrel chambered for a X.39 bolt. I guess it is possible your barrel is improperly marked but you should be able to check the head space with your x39 bolt/barrel using go no go gauges.