There's now a detailed write-up about the hybrid cartridge in Guns America:
https://www.gunsamerica.com/digest/277-sig-fury-demystified/
80,000 PSI vs. 60,000 PSI for 308
Final rounds will achieve >3000 ft/s for 140 gr out of 16 in barrel
Will work with existing Remington 700 actions but not...