Is the weapon 'NEW'?
Has it ever been fired?
Is the bolt/BCG running 'wet'?
Has the chamber been cleaned out?
Have you checked the 'key' on the BCG to see that it is on tight (and staked)?
Will the bolt cycle closed/open with little to no effort?
First things first. Break it open and look at the BCG. Check the 'key' (that snout thing that rides on top of the Bolt Carrier). It must be solidly screwed on and most (including me) thinks the metal holding those screws should be bent into the screw heads). If that is a go, move on.
Slip everything back together. Pull the operating handle back. Is there anything other than the resistance of the buffer spring? If not smooth and easy, find out why.
Drop the bolt. It is supposed to be released and fly back into battery (closed). Did it?
Run a patch down the bore and then clean the chamber. Look at the lugs on the rear/face of the barrel and front of the bolt. If all looks good, Oil the BCG. I use Mobile One, you can use what you like but the bolt needs to be wet with oil. Dry cycle the action several times. Turn the safety on. Load a mag, turn the safety on. Insert the mag. Turn the safety on. Now this is important, make certain that the safety is on and keep your finger out of the trigger guard. Cycle the bolt one time. Drop the mag. Look to see if the bolt is locked (all of the way forward). Keeping your fingers away from the trigger, cycle the bolt again to remove the round.
If at any point in this, a problem was detected. STOP AT THAT POINT.
This is better performed at a firing range and/or with non functional test ammunition.
I don't like to suggest to a person that I can't watch, to actually load a weapon that I have not evaluated. It is scary for me to think about.
This was not to belittle anyone, but to emphasize the importance of being very, very safe. The statement 'not chambering well' is wide open for interpretation.
Has it ever been fired?
Is the bolt/BCG running 'wet'?
Has the chamber been cleaned out?
Have you checked the 'key' on the BCG to see that it is on tight (and staked)?
Will the bolt cycle closed/open with little to no effort?
First things first. Break it open and look at the BCG. Check the 'key' (that snout thing that rides on top of the Bolt Carrier). It must be solidly screwed on and most (including me) thinks the metal holding those screws should be bent into the screw heads). If that is a go, move on.
Slip everything back together. Pull the operating handle back. Is there anything other than the resistance of the buffer spring? If not smooth and easy, find out why.
Drop the bolt. It is supposed to be released and fly back into battery (closed). Did it?
Run a patch down the bore and then clean the chamber. Look at the lugs on the rear/face of the barrel and front of the bolt. If all looks good, Oil the BCG. I use Mobile One, you can use what you like but the bolt needs to be wet with oil. Dry cycle the action several times. Turn the safety on. Load a mag, turn the safety on. Insert the mag. Turn the safety on. Now this is important, make certain that the safety is on and keep your finger out of the trigger guard. Cycle the bolt one time. Drop the mag. Look to see if the bolt is locked (all of the way forward). Keeping your fingers away from the trigger, cycle the bolt again to remove the round.
If at any point in this, a problem was detected. STOP AT THAT POINT.
This is better performed at a firing range and/or with non functional test ammunition.
I don't like to suggest to a person that I can't watch, to actually load a weapon that I have not evaluated. It is scary for me to think about.
This was not to belittle anyone, but to emphasize the importance of being very, very safe. The statement 'not chambering well' is wide open for interpretation.