Check out this great Krieghoff Gun Sleeve by Wild Hare (holds two barrels)
Features include:
Quilting for ruggedness and protection
PVC reinforced fabric for extra durability and water resistance
Metal snap mouth for easy loading.
All metal is completely covered to prevent scratches
Wide shoulder strap with formed rubber pad for comfort
End flap with Velcro closure
Large 7″ opening will handle larger stocks
Large accessories pocket on the outside
54″ in total length
Extra padded, 35 inch side pocket for spare barrel
Elastic Velcro straps for securing spare barrel