About all I can suggest is that you get a small quantity of the SA ammo and try three- and five-shot groups at the benchrest.
The best deal is to tailor some load to your rifle, via handloading. (You can go to the H&R forum here for some ideas.) It's not that handloading is all that cheap so much as you get the best accuracy-load for your own particular rifle. The cost-saving is that it keeps you out of the beer joints at night.
I wouldn't worry about noise and distance. The .308 is no louder, really, than a .22-250 or other PD cartridges. You shoot, they go into their holes, they come out, you shoot.
Repeat as necessary...