I got my Palmetto State Armory M4 rifle kit in today. While looking over the upper I noticed the end of the barrel does not look like it phosphate coated.
The picture did not turn out very good. But I can see the fine machine marks where the end of the barrel was crowned.
I am wondering if the barrel was phosphate coated, and then the threads machined and the barrel crowned? Surely they did not do this?
I guess I could leave the upper outside overnight and see if the metal starts to rust?
When my wife gets home from work I will have her hold the flashlight so I can get a better picture.
Not sure what you got laying around but you could:
Wrap it in leather & clamp in a vise.
or
use an upper receiver block.
or
use a Reaction Rod.
or
use an upper receiver clam shell.
etc, etc…
