Hello
I got two more 3" magnum rounds to test for pattern and velocity.

Winchester #X12XC3B5  3" 15 Pellet 00 Buck Copper Plated
FEDERAL # PFC15700  3" 12 Pellet 00 Buck Flight Control wad



The Winchester round really spread the shot out rather quickly, and velocity ok.



Now the Federal round with the Flight Control wad is another story..  It held a tight pattern out to 21 yards and velocity is up there.  Had a weird anomaly with the chronograph while shooting at the 14 yard target, so didn't get a velocity.  At 7 yards the shot is pretty much a slug.  So for shooting out at extended ranges for buckshot this one is one to consider.  Velocity is pretty impressive..





The Federal rounds could be taken out farther and still be acceptable. 

Suggest using cylinder choke with Flight control buckshot no choke needed let the flight control wad do it’s job?no need for choke.

The flite control wad is fantastic.  I think it's the best wad that has ever been made.

Sadly, it's impossible to get on the aftermarket side because the guy that patented it, simply will not let anyone do it.

It is however, possible to make very close copies on your own if you start with an unslit wad and make your own slits.

https://castboolits.gunloads.com/showthread.php?306750-Duplicating-Federal-Flight-Control-wads

The SPX comes with a cylinder bore...