Here's a pictorial outlining one of the reasons I anneal my cases. This example is one of my 30BR's and follows a case from virgin brass throughout a bit of it's lifespan. Primers are removed in all instances so as not to affect the meaurements.
#1. Virgin case ready to be fireformed. I set the shoulder at .001 shorter than my chamber. Datum line is 3.162. The Lapua annealing coloration is readily apparent.
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#2. Case has been fired once. Datum line is 3.163 as it comes from the chamber.
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#3. Once fired case is sized and the shoulder pushed back .002. Datrum line is 3.161.
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#4. Ten (10) firings later. Case has been run through the same die setup as produced the 3.161 datum line figure. Case is getting hard to chamber. Datum line measures 3.163. The brass is getting hardened to the point that the shoulder no longer 'stays' where the die puts it. It lenghthens as a result of springback.
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#5. Here's the same case after I annealed it and ran it through the die setup. The shoulder now stays at the original die setting. Datum line measures 3.161, the same as this cases measured after being fired once and run through the die. Notice the coloration on the case from my annealing process.
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For what it's worth. Good shootin'. -Al
#1. Virgin case ready to be fireformed. I set the shoulder at .001 shorter than my chamber. Datum line is 3.162. The Lapua annealing coloration is readily apparent.
#2. Case has been fired once. Datum line is 3.163 as it comes from the chamber.
#3. Once fired case is sized and the shoulder pushed back .002. Datrum line is 3.161.
#4. Ten (10) firings later. Case has been run through the same die setup as produced the 3.161 datum line figure. Case is getting hard to chamber. Datum line measures 3.163. The brass is getting hardened to the point that the shoulder no longer 'stays' where the die puts it. It lenghthens as a result of springback.
#5. Here's the same case after I annealed it and ran it through the die setup. The shoulder now stays at the original die setting. Datum line measures 3.161, the same as this cases measured after being fired once and run through the die. Notice the coloration on the case from my annealing process.
For what it's worth. Good shootin'. -Al
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