Does Heavily Used Brass Degrade Accuracy?

Not maybe but definitely test and come to your opinion. Testing is fun. You'll get some opinions here. It isn't immoral to stash old brass and start over. Tough old rifle brass trims harder. Doesn't size back or springs back during sizing. Educational to measure.

Personally, I anneal, so my necks and shoulders behave as if they're virgin brass all of the time, and I bump my shoulders only 2 thou so I'm not stretching brass, AND I don't run super high pressure loads (unless I REALLY have to) so I'm not pushing my case web apart like playdough on every firing... So I can get my brass to last a long, long time. I have a set of R-P 223 rem brass which has more than 20 firings on it. I have a set of 6 Creed Hornady brass with 17 or 18 on it now. I had a set of Lapua 6BR brass which I blew out to Dasher which I took to 24 firings, my current set is on 9-10 firings. I had a set of Winchester 243win brass I took to ~15 firings.

In GENERAL, if you're not annealing, you're going to see significant work hardening of the necks by the 7th or 8th firing, so you'll be stacking more and more change in tuning by your 5th firing, so the brass won't be behaving the same as it did when it was new. That's USUALLY the best explanation when folks see what you're seeing - that virgin brass outshoots old brass.

Agree on the annealing. I did not anneal for years and could tell brass was springing back when resizing. I also could tell that there was inconsistent neck tension when seating bullets. Most were more firm when seating. Results on target at distance were telling the tale and scores went down when competing. You can anneal with something as simple as a Bernzomatic propane torch or even a candle to something as expensive as an AMP annealer. I recommend trying to anneal those cases...Cost is minimal and you may find it extends brass life.

Lee Q. Loader said:

So, if I was start annealing my Grendel cases, are the ones with 10 plus loadings on them worth annealing at this point? Or are they beyond their useful life?

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If primer pockets aren't loose, case heads aren't expanded, case bodies aren't showing any incipient separation grooves internally, then yeah, they're worth annealing. They'll come back to a better behaved seating resistance like they had when they were new.

Lee Q. Loader said:

Also when should I anneal?

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After firing, before sizing. I decap, wash, dry, then anneal.

Lee Q. Loader said:

Should I anneal the brand new cases before ever loading them?

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No. Factory cases are annealed before sizing, so they're good to go.

Lee Q. Loader said:

One more question...If I anneal used cases, do I size before or after annealing?

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Size after annealing.

I don't have any brass yet that has a crazy number of firings. I have some 6.5 Swede with 9 firings and performs just like new but pressures with the M96 are not high at all, so I expect this stuff to go the distance and perform well. I also have a mixed batch of 30-06 I am using in my M1917 with 9 firings and I don't see accuracy degradation yet. I don't anneal but use sizing wax on the cases and I only neck size, so that really extends the life.

I'm another that believes in annealing.