Well as long as you're happy ,little else matters .
Yes I did MY testing in 1997 ,using various headstamp pieces of brass . I ran #20 of #8 brands of 30/06 including LC & RWS . New and once fired along with #20 range pickups for variable allowances and setting parameters . Funny thing because I used both Induction as well as flame ,splitting the groups into half or #10 each ** .
I used the Range pickups as guinea pigs ,varying the temp as well as dwell ,so as to ascertain the " Correct Temp " for restoring ductility and retaining some neck spring aka tension . In other words Not over cooking it . 750 Deg. F didn't do shit ,neither did 850 F. . When I approached 950 Deg. F. necks began to exhibit favorable tenancies as well as softening to a desirable HV number . 1200 Deg. F. was the Proper Temp* . As cases dropped into a metal tray ,necks dented in many cases . By accident I found out that by resizing just the once after partial annealing or ductility restoration ,that neck tension was Perfect . Across the board regardless of case manufacturer ,numbers aligned as closely as I was able to measure with New Unfired Brass . I used #7 New cases and tore down brand new loaded ammo for those ,as cases weren't available by themselves in all instances .
I also sacrificed #6 Pieces of 8X57 cases at various stages of temp and dwell attempted restoration . Our Metallurgist cut those cases and put them under extreme magnification using the High power optical comparator or metallurgical microscope . I made the illumination solution so as to offset high contrast . Using two well known methods , #1 Darkfield illumination and #2 Nomarsky Prism .
Our conclusion was as follows ; NO restructuring or lattice aka grain had been formed in any of the brass test cartridges or sacrificed save for #1 8X57 , as I cooked that in the oven annealer for #30 minutes at 900 Deg. F. and about 70% showed finer more uniform grained appearance.
The case was Worthless ,as it was way way too soft and unusable . It was however Annealed in the true sense of the meaning .
As I know of NO practical method of continually cooling a brass cartridge case , from the shoulder to it's base while cooking neck and shoulder for #30 minutes at 900 Deg. F. is why I state Ductility restoration instead of annealing .
Bottom line without reservation ** Regardless of method used Flame or Induction heated ,provided each method is done correctly makes ZERO difference to the case in regards to accuracy or neck tension .
IF one is allowing their case necks to turn cherry red ,they've gotten too hot ( But NOT ruined ( simply resize them twice .
I set dwell time for case specific temp ,less for larger caliber more for smaller caliber . It's just the opposite of what one would think but larger cases require less time to Heat to correct temperature . Color is Blue flash smoke to orange and off the flame ,as the witness mark replicates Lapua cases perfectly and brass doesn't looked like it was baked all day in an easy oven by your granddaughter .
What I can tell anyone is , It's far better to restore neck shoulder ductility then not ,regardless of method used . You can plainly see MY cases started out UGLY in real life ,as perhaps 80 years to the weather before being cleaned ultrasonically and flame ductility restored .
I've gotten #28 near full power reloads on 1942-43 original .30 Cal M2 once fired cases ,that I cleaned and induced neck shoulder ductility too and haven't lost a single case . Not even a torn rim and I'm still reloading those cases and hopefully will for another #20 reloads .
I've gotten #48 reloads out of MY 7.62X51mm LC match cases and retired them as I found #2 were thinner than I liked . I run most of MY Old cases through My M1 Garands and M14's . I do run additional AR10 style DPMS 7.62X51mm as well as 6.5 CM along with several AR-15 platform semi's and keep ammo separated ,as chambers are Not same .
Whatever works for any of you is OK by Me ,one simply can't pull the wool over this old Wolf's hide ; I've been in far to many herds