Kynoch
member
I'm not sure they could. If the margin was significantly reduced, I would stop carrying them in my store. Considering the paperwork, record keeping requirements, and relatively low volume that guns sell at, the $20/gun i'd be reduced too wouldn't make it worthwhile for me to stock them.
A retailer could maintain their margins (in fact as a % of the sales price it would actually increase) even if Glock slashed their prices which apparently they have the cost structure to do if they so wanted.
The price reduction could come from Glock and not their resellers.