Pros: higher velocityCheapCons: seamed, not smooth and wind pushes them around, so their is NO accuracy.will jam in the feed ports of precision weapons(possibly striping gears or other PERMANENT damage)NOTE: Higher velocity and/or lighter rounds DOES NOT affect impact. Yes, its flying faster, but its lighter, so the impact is EXACTLY THE SAME as a heavier, and therefore slower, round. (Some simple physics will prove this if you doubt me)I personally recommend .20g precision (seamless) BBs or heavier. You get much greater accuracy, with the same impact, altho, yes, you lose some range. But what good is range without accuracy? I use .20gs in all of my airsoft weapons-from my high grade fullmetal DMPS M-4 carbine AEG to my WalMart bought junk pistols.