Charge Difference between Lapua and Hornady brass.

[LRRPF52]

Since I began annealing about 12 years ago using a plumbers torch and a drill and socket I have never lost a piece of brass due to neck splits. I have 90 something.308 Lapua Palma brass with close to 30 loadings on them that were always flame annealed still sitting in my case storage. The few that are missing were misplaced through the years, a couple may have developed loose primer pockets. I think that is why I retired them. Not bad for brass that was bought when Obama was President and shot a couple of dozen long range matches. The way annealing works is that it realigns the crystalline structure of the brass regardless of how much work hardening has occurred. You can take brass that has been resized 10 times, mix it with brass that has been resized twice, anneal both and the brass hardness will equal out as long as the time and temperature of the heat was the same or close to the same on all pieces.

EDIT -In regard to the OP, no clue here. All I have ever used in the Grendel is Starline and the highest number of firings is 9 on the stuff I own. Rims and necks tend to get beat to crap on my gas guns. I am still working on the art of reloading and tuning for AR's

Have you de-edged, blended, and polished your feed ramps? Any work done to your ejector, bolt face, and extractors?

One thing with the AR-15 is that during ejection, the force of the ejector pushes the brass out as it’s passing through the barrel extension teeth, and you can get those vampire-like nicks on the neck. That’s not good for neck life.

You can carefully polish those teeth edges in that clock position in the extension, as well as reducing the ejector spring length to slow down the rate at which the spent case departs from the bore axis as it clears the extension.