I think my 6.8 SBR is showing promise. I haven't shot it much yet other than getting it running correctly, so tonight I took a few different handloads to the range and tried it out. The groups tightened up as the loads got hotter, culminating with this group:
Now, this was only at 50 yards, but I'm pretty impressed considering this was shot with flip up iron sights, shooting into the sun. I was having trouble seeing the target with the sun in my eyes, so I have a feeling the low flyer is shooter error. Plus, the sight radius on a 12.5" barrel doesn't leave much room for error. I have a 1.5-5 scope that I need to get mounted on this thing so I can see what it can really do.
By the way, muzzle blast from a 12.5" 6.8 SPC at max loads is brutal.
After the first couple of shots I doubled up on the hearing protection.