I have a lot of reading to get caught up on in this thread but I suggest doing the following based upon what I saw so far.
The following assumes that the mags can be made after a manufacturing ban goes into effect as long as they are paid for in full prior to the ban.
Let’s say that a manufacturing ban is set to go into effect March 3rd.
Well on March 2nd, discount your price to $0.0000000000000000000000000000000001 each and sell a few million of them to yourself, Mom, Dad, wife, brother, basically someone you trust. Once they are delivered to that person, they can resell them. I’ll bet they’d even be willing to give you a percentage of any profits. Hopefully there won’t be a resale ban on mags over 10 rounds.
Sorry if someone else already suggested this idea.