Can I use medium flat rate box for regular priority mail

[OneComment]

It's not clear. This page https://about.usps.com/postal-bullet...l/updt_002.htm says, talking about what happens if you put so much in a flat rate box or envelope that it doesn't shut properly, says that the post office is supposed to just charge you the Priority Mail weight and zone price:

"If an FRE or FRB is presented at the office of mailing and the customer has manipulated or reconstructed it, the container is accepted using weight and zone — not the Flat Rate price. A customer is not required to repackage an item unless the contents are fragile and would be at risk of damage during processing and transit."

So, it seems that there is no crime in using a FRB for plain Priority.

But, I would like a definitive answer.

[rsot]

Welcome to the forum OneComment - all the best as you master stealth

[phaz0rz]

It's perfectly fine, OneComment. I've been doing it for years. Unless my post office is just slack, they really couldn't care less.

[BigCJ]

I do it all the time. And if you are really worried, give it to a truck driver and let him scan it. It ill bypass all that nonsense.