Thanks for all the insights on this.
I'll see if I can source an Armalite bolt catch and I'll report on whether it makes a difference.
After loading up a Lancer Magazine, the rifle passed a function check no problem.
This SBR build came out sweet and I'll list all the parts that went into it someday. Just about every part came from a different source and I had to return some of them due to either fitment problems or shipping damage.