Ehyup Ken, youve asked this before......
The technical answer was back then, the same as it is now;
"The Barley Twist barrel 100's usually sell for more second hand - so they are better!"
You shoot 15mm 5 shot groups at 55 yards? How do you ever miss a target on the course?
Or is that 15mm groups at 55 yards and 3 and 1/2" groups at 30 yards