I’ve had some fun experimenting with the Chaser and it’s a pretty enjoyable little rat gun. Those 14grain wadcutters might lean towards the lighter end of the power spectrum but for close-range pest control, it definitely gets the job done if you aim well. From what I’ve seen, most people I know have better luck just switching up their pellets instead of trying to squeeze out more power. A domed or pointed pellet usually holds onto its energy better than a wadcutter once you’re shooting beyond a few yards.
How far are you thinking of shooting these rats? And are you using the pistol setup or the carbine kit? That really changes what you can expect from it