the reason I ask is I was arrested once and no charges were filed by the state,I was innocent and my arrest record was expunged. I can pass a nics check for a firearms and have a carry permit as well. Is it possible some new legislation down the road could ban me from firearm ownership,because I have an arrest on my record?
No.
What it can and possibly will do is cause any LEO contacts you have to consider that arrest because it will still be on record when they pull up your name.
I assume it is an arrest that would have removed your right to firearms had you been found guilty which is why it concerns you, so let me give examples:
This can cause them to be less inclined to give you the benefit of the doubt in discretionary situations. Or situations where it is one person's word against another.
So for example some guy attacks you, and you defend yourself. You say what you did was self defense, but you have a prior arrest for a fight or weapon violations or something else that says violent or dangerous to police, etc (even though not found guilty.)
The police are not sure what happened in the latest situation having a few possible scenarios in their heads, but seeing that arrest record side with one less in your favor and write their report accordingly.
That can easily lead to a conviction that may not have resulted if they had not written the report in such a manner.
That conviction may then remove your firearm rights.
Domestic violence would be another example. An arrest for it at one time may result in officers believing an accusation in the future, even without any prior conviction. That could result in a report that is slanted more against you being written that results in conviction and loss of rights. Meaning if you have one wife or girlfriend that tries to falsely accuse you it lends credibility to future false accusations when the police or courts see prior arrests. Though they are unlikely to mention the prior arrest record, they will certainly have it in their minds when dealing with you after having looked you up.
What this means is even if innocent of what you were arrested for previously, a list of arrests can very easily count against you in the future damaging your benefit of the doubt or credibility in the eyes of those who can see those arrests in a computer.