I don't think a .204, 26 grs bullet is tooo light.... But then I shoot some smaller 20s too like a 5mm Mag centerfire conv and a 20 on the 221 FB. In the 204 Ruger it should hit some high velocities and really make a mess out of a PD! The standard 12 twist will be just right for em but with the 50 gr .204 it might be iffy. I have shot the 50s from my 20 BR with a 11 twist just fine but for the heavier 204 bullets I would think a guy needs at least a 10 twist and a 9 would be better but that is just an opinion and no facts to base it on...
I hope that the 26 gr bullet will be short enough to load into the magazine of the 5mm Mag, my cast 30 gr rounds nose will fit just fine but the plastic tip bullets are toooo long!
Now someone needs to come out with a real small 20 (like the old 5mm Mag!) to shoot these lighter bullets in....