AR-Stoner 6.5 Grendel barrel short chambered.

[FlatsFlite]

What ammo was getting stuck?

I seated five 123 gr Amax dummies at 2.260. None of the rounds would ease into the chamber. Using the bolt release, all five seated until the bolt locked. Three measured 2.2385 after extraction. I had to mortar one out, it measured 2.237. While mortaring the last one out, the bullet stayed in the barrel, the casing extracted. All five bullets had extremely thin angled marks evenly spaced around the bullet. Starting the tip toward the base about .400" long. None were crimped, but the neck tension should have been sufficient.

I set another dummy with an SST bullet. I still had to let the bolt fly to get it locked up, but it maintained 2.260 measurement upon ejection every time.