Have a look at these scoring marks. They only showed up on the part you see here but they are on most of the case body.
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Gentlemen,
I am by far no expert, however I have shot on a 4 man ASA team for some years and been blessed to learn from the 3 brother's I shoot with; to that I shall only add that I have been machining for a bit over 35 years and though I now do it with computers, the practicality of cutting and forming metal remains the same regardless.
That being said I am simply going to interject a couple of variables which I believe would be worth examination. Though as of yet we have not begun to anneal our brass, with geopolitics being what they are we may be forced to start. Since that may be the case I have began an in depth study of the annealing process relational to load/caliber/our primary powders and pressures/ our standard primers, etc., etc....you guys know the drill. Please understand that in our group, between the 4 of us we are firing at range(400-1000yds) three very different rifles. 2 308's, mine being one(an FN former psr, modified it to my comfort), an 8mm Mag, and a .265 x 55 custom. I state this because the .375 cheytac and .338 Lapua Magnum are truly "different" and special creatures among the rifle community. I have found through research that we as a team should be fine and enhance at least twofold our number of reloads. I have also seen that because of the metallurgical properties of rifle brass were we to be using larger calibers and building much higher chamber pressures I would not agree that the cause outweighs the effect. Lapua is obviously the teams preference and for good reason. The Company has very stringent controls on the metallurgical composition of their base product as well as their production processes which yields what we all admire. However, brass is extremely unique in the way it reacts to its environment. We all know brass as the great material which we use to "seat a bearing, or give something a useful tap to adjust it for welding without damaging the surface we're striking" and that's all true but look at what's labeled 'Naval Brass' which is named such for its uses on American Aircraft Carriers and other seagoing vessels because of its mixture of anti corrosiveness as well as its toughness to hold up under pressure, then examine spinodal bronze which is mostly brass with a few very exceptional ingredients which yield and extremely durable material specifically in the region of repetitious action and reaction which is used highly in the hydraulic units of our Apache helicopters because of millions of repitions that their primary and redundant systems utilize. The straight answer is that, not from an expert but from one which knows metal, I would begin to examine the metallurgical properties of the brass which I was purchasing, then delve into the 'ability' of said brass to recover by annealing in order for extended reloads.
Let's face facts, my FN barrel is great but after between 6000 and 9000 rounds, I am actually breaking down the internal grain structure of its metallic composition and as it degrades it will flex and move in ways that are mathematically unpredictable which will ultimately lead to me replacing my barrel...then my journey begins all again, seating depth, powder dump, breaking in a new snout, we all know the process.
I suppose if anyone is to take anything away from my examinations, it would be first and foremost know your brass's metallurgical properties, second it appears that in the larger more powerful calibers you will find greatly increased difficulty in pinning down a great process for annealing, much akin to rebuilding a .396 big block to stay together at 8000 rpm as opposed to a .350 four bolt main which is cake, and lastly know your chamber... As I read through the comments and photos, as a labeled "Master Machinist", dod's words not mine, I can identify with the post that pointed out the score marks on the base of the brass. By optical comparator as well as experience I can assure you that by the very aspect of the process in which a reamer forms a shape it will not show its wear until it's within roughly 25% to 40% of the base of its stroke. To be more precise you will begin to see deeper lines higher above the terminus of its travel which will seem to diminish as it goes to depth and finally almost disappear at full depth wherein it will appear to be a simple band around the diameter. This is caused by what Machinist call 'lead effect' which simply means that the deeper the reamer gets into its projected axis(hole) the less it will run out from its holder and the spindle that is driving it. Note that ALL reamers,unless otherwise ordered from the manufacturer, will have a tapered or angular lead of approximately 5% which shows in the solid ring at the base of your brass plus travel of the tool...bluntly put, you should have a certified gunsmith do an impression mold of your action and place that against an optical comparator mathematical read of the tolerances of the blueprint which your rifle manufacturer should have available online.
Thanks for your time, hope this helped...
Vaelin
