I will happily test the barrel tuner in 10/22 factory barrel and 20" fluted .223 Wylde barrel to see if it improves accuracy.I bought 1 for a 6.5 CM. No help with accuracy.
I actually considered the $9 barrel tuner when I was doing the "Accurizing 22LR on the cheap" thread but realized the tuner won't be much help when I was doing 30+ brands/weights of ammunition (Now testing 47 brands/weights/lots of ammunition between rainy days working on rainy day shooting setup).I ordered 5 for my thinner barrels. My bull barrels do good with out.