An empty sized brass case gets it's neck smashed pretty good.
Have you measured the brass overall length to see if it needs to be trimmed?
Find a dimension drawing of the cartridge case. Measure what you have. Be sure to check shoulder diameter.
Remove your upper. Pull the carrier out. Inspect,with good light,the chamber and throat area.Look in the locking lug area for obstructive trash.
Look where the gas tube enters the upper. Does it appear "centered"
Check over the bolt carrier. Does it function freely? Is it lubed? Are any pins protruding? Does the ejector plunger move without "crunch"
Taken as the whole rifle/ammo assembly,it may be overwhelming.
Broken down to its simplest one on one relationships,like many other things,its really not much more complicated than tinker toys,legos,etc.
The round peg goes in the round hole,or it does not. Find out why.
Ease.Observe. Maybe scraped magic marker tell a story. Generally,a thumb ad forefinger provide enough "force".
If you get tight jawed,put it down. Nothing about an AR should require more than a pin tapping hammer unless you are undoing another screw up.
When a collapsed shoulder case gets slammed into a tapered chamber by the bolt carrier/buffer spring,it CAN get really stuck.
Try to avoid letting the bolt carrier slam questionable ammo into the chamber.
You have the upper detached. Bolt carrier removed. You are looking at the chamber. Any cartridge component should drop in,drop out.
If it does not,don't force it. Worst case,a cleaning rod will push it out. No hammer required.
A little Sharpie ink on a tight brass case will reveal tracks where there is a tight spot.
Avoid hammers,files,Dremels,cordless drills,and wooden dowel rods.
As this is an unfired gun,did you clean preservative grease,machine chips,etc,then lube it?
I know.Those contaminants "should not be there" Murphy's law.|
It COULD be a factory defect. But those are quite rare.
Guns,if we set emotions aside,are largely tinker toy and legos level mechanics IF we can avoid doing any harm
