I ordered some parts from Mossberg recently but I did not press them for a delivery time because I was not in a hurry.
I'm pretty certain that Mossberg is like most manufacturing companies I have worked for. The production and the shipping departments have a backlog of work, by design because you simply cannot afford idle people in these departments.
Certain orders can be expedited through "the system" if you know who to talk to and what to say.
Of course they must physically go through this. They must find the paperwork on your order, figure out where it is in process, track it down, and tell the supervisor to move it to the head of the line. Of course now the supervisor is owed a favor, because now the supervisor must physically go to the production line and disrupt business there. The supervisors production just went down.
As a manufacturing engineer, I always hated this problem; but it's something you deal with it in industry where things break down and people need spare parts.
This is where a bad design just kills your profit margin. It doesn't cost Mossberg much to crank out or order out a thousand more of those little extractors to replace the ones people broke.
But the process of getting them installed he's a killer.
Poor designs ruin small companies and that is why the ones which survive always seem to have really great designs and good craftsmanship.