I have mixed results with dealing with GM.
There are 2 within an hour of my house- one is 5 miles away.
Their selection is pretty good, The prices on guns seem to be in line with other gun shops in the area. The quality of the staff varies greatly. I actually go to one store for advice and purchasing higher end fishing reels and rods, while I go to a different store for firearms related stuff. I've heard a lot fo strange things from the guys behind the gun counter nonetheless.
They have racks and racks full of used long guns, though I haven't seen anything that was a bargain yet, including a shot out Romanian M44 with a tag describing it as "Russian service rifle, $299"
They are a quick stop place to buy reloading components and gadgets though at somewhat inflated prices. If you are looking for dies in anything other than the most popular cartridges, you won't find them here. About the only thing I buy there is primers an powder.
I had a scope mounted once by GM, they did a good enough job of mounting it, but the $20 bore sighting job they did was only off by about 1' at 25 yards.
I had the serving rewrapped on one of my bows, which came apart after shooting 3 arrows.
I've never bought a gun there, but I've window shopped there extensively to try to find exactly what I want before going to a local gunshop.