"Operation Choke Point"
Operation Choke Point officially involved investigating banks that dealt with "high risk" businesses, in order to pressure them to drop their customers. Now it's becoming obvious that its targets include licensed firearms and ammunition dealers. (It also was expanded to payday lenders, for no apparent reason except that the government frowns upon them).
Sounds to me like a possible case of tortious interference with contract. That's a clear case where someone has a binding contract of fixed duration, and someone else does something to lead the other party to break the contract. It's less clear where the contract is one that doesn't have a fixed duration, but in practice will continue until something happens; it's less clear because in a free market you want someone else to be able to outbid the current contract holder and offer a better deal. But here, there is no better deal being offered. It's straight out use of government harassment aimed at disrupting a contractual relationship, without economic benefit either to the bank or to the government.
At the same time, the Administration is quieting banks' fears regarding lending to marijuana distribution companies. The banks were worried there for the obvious reason that the businesses' activities are Federal felonies, albeit the law is generally not being enforced. But that could vanish with the stroke of a pen, or the next election, and then whoever knowingly aided the business would be guilty of those felonies, as one who aided and abetted them. Now, there would be a "high risk" line of business!