I suspect that the old letter would protect you, UNLESS it can be shown that you were informed of the new changes, but you can still have problems due to that. Part of the problem is that this forum can be used to show that you were informed of the change.
The BOE should be required to inform businesses of "changes", especially when the law does not change, only their view. I have to wonder if their view would be upheld since the law does not specify the things that they are claiming, but the bottom line is that the risk is not worth it.
The whole thing is a mess.
FFL Transfer/Special Order Dealer since 1993.
Net-FFL list maintainer.
Never try to teach a pig to sing. You waste your time and you annoy the pig. - Robert A. Heinlein