Citizens in other countries must register and even obtain a license for each and every firearm. Your governments know exactly what you legally own. In the USA, our government does not.
The 2nd Amendment of the US Constitution states that our "right to keep and bear arms shall not be infringed". Our Constitution also states that our rights are given by God.
In the USA the Constitution is our gun license. We do not have any national gun registration either. Posting photos of an entire collection could be used as a de facto registration. Yes, this can happen such as in New Orleans a few years ago when police confiscated firearms during a hurricane.
As a law abiding citizen I can go to a gun dealer and buy a new gun, or two, or three and so on, every day of the week. No license required. Some state and local laws may restrict the quantity and frequency of purchases. I believe those laws are unconstitutional but to prove that and overturn those laws, it takes a lengthy legal process.
Even though our Constitution states our God given gun rights, we here must be vigilant of increasing "weaponized" Federal Government, left wing liberal loons, and Disney-watching sheep who think that guns are bad.
It is in our best interest NOT to divulge our collections on any public forum.
Finally, this is a great video explaining Americans and our guns: