The feed ramp and receiver interface looks bad. The feed ramps are horrendously rough, and the chamber and barrel extension are FILTHY. My guess is that the horrible ramps are not tolerant of OTM bullets... whereas FMJs will make it into battery.
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The feed ramp and receiver interface looks bad. The feed ramps are horrendously rough, and the chamber and barrel extension are FILTHY. My guess is that the horrible ramps are not tolerant of OTM bullets... whereas FMJs will make it into battery.
The copper jackets of the bullets are very soft compared to the steel of the barrel & barrel extension. The bore will wear before the barrel extension because of heat & erosion the bore is exposed to. Not saying the feed ramps have no defect, just that it's not due to wear from feeding copper jacketed ammo.
Before sending your upper back, load a single round in your magazine and perform a lock back check, making sure the bolt catch is fully engaged and not just partially hanging up the carrier. It's possible your rifle is short stroking