Great deal on FX Panthera Hunter Compact coming to me.

Looking at FX's site on the rifle, they show 68 grain slug for their velocity data for .30 and 43g slug for 25. This puts their velocity's below 900. I wonder why? Is their rifling set up for longer slugs? I wonder what the twist rate is, or is it progressive?

Anyway when I first looked at the data and saw .30 cal velocity at 840 I thought not enough gun for the .30. But that's not the case. Shooting a 55g slug the rifle should be in the low 900's which is pretty powerful and a good velocity for accuracy in my guns.