I also have have 7 Dakota
(albeit in a center-grip Rem. XP-100).
My barrel is just hair short of 18 inches and I have only used 200 WC's with my accurate load running just over 2700 FPS (Lilja 1-7 twist) using Retumbo. I have never even used another bullet to date and don't plan to either. But the 162 AMax, 175 SMK and the 178 Carteruchio would also be bullets to use. I have also spoke with Dakota Arms about components and recieved the very same response as Kirby did. Kirby built my XP. Redding makes a shoulder bump body die for the 7mm Dakota and then I had Kirby ream out a comp set of Redding 7mm RM dies. This XP could embarrass a lot of rifles (I'm not talking about the rigs you LR guys use here) with it's accuracy/high BC bullet.
It will be my cow elk/muley buck rig for Colorado this year. I have never had such confidence at longer ranges as I do with this rig. If conditions are good and I don't pull a stupid it should shine well for LR specialty handgun.