Don't have a .177 PCP but tried them unsuccessfully in a Nitro Piston Crosman F4. 2muchair4leyla, one of our members with an FX M3 in .177, said these were terrible and only good for administering a final point-blank head shot. WM
Rabbit magnum is a slug, not a pellet, although classed with pellets. If your rifle has the rate of twist to shoot slugs, then it would make an excellent addition. Nothing I have will shoot them reasonably accurate.
JSB Monsters and Beast are my go pellets for my Edgun Lelya 2 in .177. Eunjin/Seneca do okay but they are no where near as accurate as the Monsters and Beast.