Barrel suck involves any projectile moving down a barrel propelled by air. It involves the lower amount of air from the cylinder not being able to equal or excede the volume of the barrel. So it doesn't matter if it's one shot per minute or 800, barrel suck occurs due to the barrel volume being much higher than the cylinder volume. It doesn't come from the piston moving backwards, it comes from the vacuum created when air volume behind a moving BB excedes available air volume from the cylinder.
And yes, deburring, crowning, etc. needs to be done on the barrel if you cut it, you can put the hop up end into a drill to spin it and use a small fine file or large drill bit to do it cleanly.
Last edited by CDN_Stalker; January 3rd, 2011 at 19:54..