I was at the Eastern Out Door Show in Harrisburg Pa and Nosler was there with a display of rifles and they had an inert 26Nosler round you could handle. I was told all the sample rifles are out on loan to the gun writers and there should be some results soon.
It is based on the 7mm Rum case which was shortened. I was told it took four different steps to make it from the Rum casing. I was also told that Best Of The West rifles wanted a reamer to work up an AR platform for it.
I included a pic of the 26Nosler with me holding it. It looks like a fat 6.5-06.