hi, i own a mossberg 500 (12 ga, 28" synthetic, 5+1). use it only for clay shooting at the moment, but looking into being able to use it as a tactical gun as well, i.e. shorter barrel on it while at home and go to a longer barrel when shooting pigeons on the weekends... i like the 8+1 built-in capacity of 590s but dont wanna get another gun at the moment, and because of mossberg's unique, aka frustrating, design of magazine tube, no aftermarket mag extenders are available, at least to my knowledge. so what happens is that the barrel has to be exactly matched to the magazine tube... and i was wondering if i could just try and find a 590 magazine tube and an accompanying 18.5" barrel and be able to fit it to my 500? thanks