The virtues of 300 blk wasn't to serve as a viable alternative to x39. It is simply the most versatile round for the modern day AR platform out to 300 yards. I run a 9.5 inch sbr that has more muzzle velocity than a 16 inch 5.56 in a smaller platform. I run linked ETM mags and a suppressor. If my target engagement moves out over 25-50 yards and/or behind cover. I simply switch mags to the supers, have the same reliability, no gas tuning, bcg switches to mess with and start up some hammer time.
Try shooting quiet with subsonic x39 suppressed, let me know how your bolt action AK/AR works for you. Try shooting through brick walls or outside of 50 yards with your Kriss Vector and let me know how that does for you.
Can you give some advice on how the 300BLK would work in a 10.5" barrel for hunting deer and also for home defense suppressed... Is this a good idea or not?