These are just my observations and really only apply to my limited experience with FS.
Another thought that may have some merit is the gelatin compound of the paintball shell and the plastic shell of FS. I am sure there is a big difference in drag, plus the projectile shape has one of the biggest effects on velocity.
The biggest thing we discovered was the size difference in the FS 684, 685, and 686 (which is pretty good for a production plastic part ) and how it was effected in a one size fits all barrel.
The first clue was vertical string of shots varied as much as 20 yards downrange under the target with tight fitting FS and over the target with loose fitting FS. That's when I started sizing the FS and noticed I had a better shot string when I shot all the same size FS.
As a test the 686 FS would have to be forced into the 684 sizer and the gun would not shoot it out of the shell sizer let alone the barrel.
In order to have a happy medium on barrel size we ended up with a 689 barrel bore.
Just to throw in something that makes no sense is I am testing the END Game barrel from the $aint and this barrel defies what little I know about barrel bores. The bore looks like it has drill swirl in it. It does not appear to be honed. It pinned .689. I think it's 20" long or so. And it has been one of the most accurate barrels I have shot on my SR1.
Go figure. I am going to do some bench rest with it soon and see what happens.
It's a lot of fun figuring out what make the FS work. I think we as a paintball community are on the edge of something new and exciting in paintball projectiles. I think 100+ yard consistent one shot hits are just around the corner.
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