Try this simple test - 2 hose clamps and wheel weights to total mass is 3, 4, 5 and 6 oz.
STrap them to the barrel at the same place and shoot your best ammo. At 300m, did it change much? Did the groups get much bigger? Which weight had the most positive change?
Of that weight, move it 1/4" and 1/2" and see how it changed.
This is big adjustments to see if your barrel will respond positively to the mass of a tuner.
for my primary barrel, it either didn't have a significant affect or caused groups to get much bigger.... I don't have a tuner.
Another team mate has been struggling with a barrel but got a very pleasant surprise when he strapped on a magnetospeed bayonet. Groups at 300 cut in half.... just like that. He is going to pursue a tuner or at least an equal mass.
A tuner is nothing more then a pretty hunk of weight so test to see if this mass is going to help or hurt. And since you know how heavy you need to install, these are the tuners you are going to install.
YMMV.
Jerry