[stuartcr]

I see nothing wrong with an officer that has been called out on a gun report to check out what is happening. I imagine the registration comment probably meant a check to see if the weapon had been reported as stolen or used in a crime.

[Slump Tester]

I suppose you'd have no problem giving him your ID, and having all your info go on a police report either.

Unless you are breaking the law, or he suspects you are, the cop has no lawful reason to detain you, seize your gun, demand your ID, detain you for any length of time, etc...