They may have legal restrictions on selling parts now as well. Not that I'm sticking up for Mossberg but you never know what crap they are dealing with as far as all the new gun laws. Or since it's such a new gun and fairly expensive they could have legal issues selling parts when alot of the 940's would be still under warranty and can't have people fiddling with them for liability reasons. Again... no idea and not sticking up for them but it's not an unreasonable assumption.
If I was a manufacturer, and I kinda am.... my shop makes a lot of things for different companies. I wouldn't want to sell parts. If the end customer has a problem, the company doesn't call us for parts, they bring the entire unit back for repairs or we build a new one. This way we know there was a problem, what it was, and we know it was fixed in house so we can continue the warranty. If we sell a customer parts, we have no idea if they used the parts to fix it right or if they were even the right parts to solve the issue in the first place. How could we still honor the warranty knowing someone else took it apart to try and fix it themselves? Legally it's easier to just say... "send it back and don't touch it!"
And if you sell parts you can't just assume it's for upgrades, you gotta take all that into account.
So, it's simply not always a issue with the company not wanting to support the customer and sell parts...
Again not sticking up for them, just providing a different point of view.