I am interested in purchasing a .308 Win SPS tactical with 20" barrel. What can I expect for muzzle blast / noise / flash from the short 20" barrel in comparison with a .308 win in a 24" or 26" barrel. Any other 'negatives' or issues I should be aware of before deciding on the purchase of a 20" barreled 308 Win ? The rifle will be used for target gongs out to 600 yards + and some hunting out to 400 yards or so. Interested in shooting 165 to 180 grains bullets.