For future readers of this thread, my 7 SAUM ADG brass has necks that are over 0.016" thick. It is from what was probably the first run of ADG SAUM brass though so not sure if it has since changed.
I'm not sure what's out there for 6.5 SAUM reamers now but when I had a couple chambered the GAP standard reamers were 0.2964" necks that required turning of the R-P and Norma 7 SAUM brass that was available a decade ago but worked well with hornady and ADG 6.5 SAUM brass that came later. There was also 0.298" "no turn" necks that in reality were still too tight with unturned 7 SAUM brass. Suffice to say, the 16.5 thou necks on my 7 SAUM brass would need turning in both of those chambers if it were necked down.
A little further tangent - When i was building a 7 SAUM and ADG was just starting to make SAUM brass, a lot of gunsmiths had 0.315-0.318" neck chambers. That is not big enough at least for the ADG SAUM brass I have, gunsmith chambering my first barrel had to rent a reamer to avoid clearance issues or mandatory neck turning.