Better to mod the Thunderbolt to get the appropriate RC - personalized grip, underbarrel weight, and an accessory stock (explicitly legal for pistols). Meanwhile, you've still got enough slots for the Improved Range Finder and Additional Clip; and all your accessory locations are still open. Alternatively, you could grab the Firing Selection Change to make the thing FA, but it's hard to get the further 3 or 4 points of RC. If you ditch both the IRF and the Additional Clip, you net two slots to work with, but there's not much to use it for RC-wise, so you're looking at dealing with -3 or -4 from recoil - if you don't mind that, then this works out for you. Personally, I prefer to keep my recoil fully compensated.