I have a 26 Nosler sitting here ready to hit the range again tomorrow. It is a Sako L61R action with a 26" stainless Krieger 5R, #5 bull sporter and a 3 port Muscle brake. Being that it is a hunting rifle, after load development, it will get shot pretty much only at game so I'm not real concerned with barrel life.
However, the thing I've noticed with about 50 rounds down the tube is that it is pretty high strung. By that I mean difficult to load for as the power ramps up real quick when using relatively fast powders (for this chambering) like Magnum and RL-33. I suspect this is a result of a case only 89% full of powder at max load. Even H50BMG pressures out at a 96% filled case. You run anything faster than Magnum and the case gets even more empty and you risk detonation.
The only powder I have seen data on that will not pressure out before the case is full is US 869 - but of course I haven't seen any of that around. From testing so far I think Magnum and RL-33 are not the best choices and I plan try to smooth out the response to incremental powder additions and attempt to lower a relatively high ES by picking up some H50BMG (I can get that) and see if a slower powder and 96% full case is more consistent. I'm pretty sure that it will be. Now if I could only find some US 869.
This thing is fast however. Some of my loads (bolt a little sticky) are running the 127 grain LRX at 3,500 fps but that is a bit too hot. I'd like to find a good load around 3,350 fps and I'm hoping H50BMG is the ticket.