There are few places I don’t (can’t) carry mine. They include federal buildings, local, county and state buildings that have metal detectors at the entrance, and any place that posts no weapons. Other than that, I can carry pretty much anywhere, and do. That includes banks.
The subject of OC inside banks caused a minor kerfuffle when the OC law was being considered here in OK a few years ago. It was settled when it was pointed out that the largest bank holding company in the state, Bank of Oklahoma, was also the holding company for banks in AZ and CO where open carry was already the law. The bank said they had no problems in those states and had no reason to expect otherwise here. Common sense prevailed...
I open carried into the local bank in the mid 70’s and no one thought anything of it. Small town in central Pennsylvania.
A year or two ago a robber was stopped by the president of a small bank in Missouri who was wielding his own sidearm.
In Texas, a few banks tried to claim that federal law required them to ban guns on the premises when the CHL law was first passed in the mid-90's.
When asked to cite the law, and notified that they were assuming liability for creating an "attractive nuisance" by announcing that anyone entering/exiting the bank was not armed, almost all of them took down the signs.
You are probably wondering about that last part: it's actually true in Texas, under case law. If you create an environment that is conducive to commission of a crime, you can be held liable.
As far as I know, no one has been held liable for a crime after posting a "no guns" sign in Texas. But, the notification was apparently enough to get the lawyers in a number of big companies to react quickly.
Walk in and yell “I’m rubbing this bank” then head to the nearest wall and start rubbing it ....