i was thinking more along the lines of weight, the hw90k is like lifting a small car to shoot. im only little ,with little arms lol. the s510 is lighter. ive held the bsa in the shop and there is no weight to it, and the amount of walking i do on a night out it would be so much easyer . plus ur point is valid , since both my shooting buds both have psp's ones got the s510 like i said and the other is shooting a rapid 7 custom