Big Ed, They sound like a good arrow but with that weight and spine, I would just go with the Beeman Max4's. Their heavy hitter is a .300 deflection, 12.5 grains per inch dart with the HIT system (making it very thin) and a durable finish. If that's too heavy, they have a 11.2 gpi .340 deflection Max4, or the Black Max with 10.4 @ .340 and 11.7 @ .300. That way I don't have to even mess with a tube or two part insert/ over cap. I would love to see how those Black Mambas work out in the future, because they sound like a great idea. They just need to make one a bit heavier and stronger.