Not sure about the guns but many of the 'X-Mart only' fishing reels do scrimp on parts here and there. Maybe plastic bushings where the standard models have brass. Stamped steel parts vs. cast, etc.. They know that the average user will never notice any decrease in quality or performance and they can shave a couple of bucks off the mfg.costs. They also do it on other things like cameras, printers, and other electronics.

I would bet that they (X-Mart only products) are not identical but a standard Remington 1100 or Weatherby Vanguard is identical to the ones sold in the smaller shops.