Adjust your seating for the Corelokts and see if that helps. The different ogive of the bullet creates a different "jump" into the lands. Also you might consider upping the powder charge just a hair, the flat base Corelokt bullets are taking up less powder space than the SMK or SGKs.
Good luke finding an accuracy load with the Corelokts. I've had good luck with them in 8x57. They may not be sexy but they shot plenty tight for a milsurp Mauser.
Machine guns are awesome until you have to carry one.