In school I had to buy an expensive textbook called "Statistics for Social Scientists." It opened by explaining how most scientists can run experiments and lab trials in order to test their theories. Because of ethical concerns, many of the important questions social scientists ask, such as "why do wars start," are both immensely complicated and don't lend themselves to field trials. These circumstances require statistics. "It just so happens," they concluded, "that they gave all the easy questions to the physicists."
As a new shooter/hunter, I'm definitely drinking from the fire hose. Juggling the dozen things that can go wrong with a rifle, and the 100 or so errors that we humans can commit at the trigger, it's very easy to fall into hypochondria when something goes wrong with the system. So when a respected shooter like Jim (Backfire) with a record for promoting the 7PRC starts telling haunting tales about carbon rings on wiz-bang cartridges....I go running for the Rokslide wizards.
In the end,
@Formidilosus and others were correct when they pointed to common issues with CX bullets and encouraged me to start my troubleshooting by sending different kinds of bullets down my barrel. It worked. The markedly less shitty groups with the Federal ammo are proof, and I'm excited to see how much I can tighten them up with better riflecraft.
Had they not shared this experience, I'd probably still be down in my basement grinding away trying to clear a non-existent carbon ring off of my chamber throat. But that said, I think it's generally wise to be respectful of folks who haven't been as lucky with their rifles as Form and others.
In the second video I linked to above, Jim at Backfire did demonstrate pretty conclusively that residue from gilded metal casings were fouling the performance of his rifle with copper bullets. After a thorough cleaning, he was back to sub-MOA.
Regardless, I'm grateful to both camps here for their experience.
