To all:
I have been asked by multiple people what the point of the 6UM is, or when/why someone would choose it. It’s pretty simple- hits rates at distance for the amount of recoil.
If someone is shooting 600’ish yards or so, and isn’t comfortable for whatever reason or isn’t legally ok with using a .224 cal on deer/elk; a good 6mm such as the 6cm is the choice. It can be very effective past 600 to a long ways out, the farthest I have experience with a 6mm on a big game animal is 970 yards (elk), that was taken cleanly by it.
However, beyond 600 to 700 yards or so, lots of people go bigger for whatever reason- sometimes legitimate such as wind drift; mostly they go bigger due to a false belief that bigger is “better” at distance. The 6UM is a way to up the ballistic performance of the standard 6mm’s while still having acceptable recoil.
My experience is that I f someone isn’t shooting lots of rounds (thousands) in practice at distance every year, then they are not “outshooting” normal rounds such as the 6cm, etc., and probably should not be taking shots at distances where a 6UM makes sense. Having said that, if someone is practicing heavily at distance, is competent and on demand capable of shots in field environments past mid range (600’ish yards), is pushing shots past that range on animals regularly, or wants an increased hit rate due to wind or a better danger space (DS) at medium to long range for rapidly moving animals (rutting bucks for instance), then the 6UM is fantastic. It has a legitimate terminal effective range beyond 1,100 yards; and it does so from a 20” barrel that recoils like a 6.5cm.