Lloyd, do you have a link to this rifle?
Given Gamo's propensity to cater for the Magnumitis crowd (no judgement here, I love high-power springers), I have waited for when they come up with a .25 cal in their current highest-power model. Those lighweight synth mags will likely behave the best in that caliber. One thing I shake my head with the Gamo materials is their insistent, false claim that the Gamo Magnums have a 33mm piston / chamber. The fact is, they are 29mm guns, that have an OUTSIDE receiver diameter of 33 mm. No-one but Gamo uses the outside measurement, which is meaningless (a Walther LGV has a HUGE outside diameter), but Gamo feels the need to boast they have bigger powerplants than anyone, when it's simply not true.