I have an FX Crown MKI .25 that I have been trying to shoot slugs as accurate as I can. Most of what I've read mentions more velocity with slugs for the best accuracy. My tune is maxed out for the most velocity I can get at 145 bar is 850 fps. I'm presently shooting NSA 33.5 grain slugs with a 600 mm Superior liner. I can't get more velocity than that with my rifle now. Would going to a Superior Heavy liner with a twist of 1:18 give me more accuracy than my present 1:24 twist that I have now. Just of note, I have already expermineted with all the lighter NSA slugs, which do give me more velocity, but accuracy is much worse.