Maybe, but likely at higher prices and higher levels of quality.
How long would it take to fill the void in car availability if GM actually closed? About 48 months. During that time, yes prices would rise, but then they would come back down.
As prices rose for firearms, the number of entrants would also increase.
If you shop around for an AR, there are tons of options. Many rifles would also start getting pulled out of the closet and rebarreled. Most people who exercise the 2A don't own just one.