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Rifles, Reloading, Optics, Equipment
Reloading
Developing Load for 168 Berger New Brass vs Once Fired
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<blockquote data-quote="Bart B" data-source="post: 656373" data-attributes="member: 5302"><p>I don't think that's a good way. How much the case expands at that point depends a lot on two critical things. One's the ductile properties of the cartridge brass as well as how thick it is at that point. The other's the difference in diameters between the chamber at that point and that point on a new unfired cases.</p><p></p><p>I've taken Federal .308 Win. match ammo from the same lot then fired it in a minimum spec SAAMI chamber Hart barrel and a mil spec 7.62 NATO chamber in a match grade arsenal barrel in a Garand. Both had identical bore and groove diameters but the mil spec chamber was a couple thousandths larger at the pressure ring point than the SAAMI chamber. Same ammo had almost 1/1000th difference in pressure ring diameter; the one from the mil spec chamber was bigger. Peak pressure was pretty close to the same amount in each one at least by how the primers were flattened and muzzle velocity was only 40 fps slower in the 24 inch Garand barrel compared to the 26 inch Hart barrel in a bolt gun.</p></blockquote><p></p>
[QUOTE="Bart B, post: 656373, member: 5302"] I don't think that's a good way. How much the case expands at that point depends a lot on two critical things. One's the ductile properties of the cartridge brass as well as how thick it is at that point. The other's the difference in diameters between the chamber at that point and that point on a new unfired cases. I've taken Federal .308 Win. match ammo from the same lot then fired it in a minimum spec SAAMI chamber Hart barrel and a mil spec 7.62 NATO chamber in a match grade arsenal barrel in a Garand. Both had identical bore and groove diameters but the mil spec chamber was a couple thousandths larger at the pressure ring point than the SAAMI chamber. Same ammo had almost 1/1000th difference in pressure ring diameter; the one from the mil spec chamber was bigger. Peak pressure was pretty close to the same amount in each one at least by how the primers were flattened and muzzle velocity was only 40 fps slower in the 24 inch Garand barrel compared to the 26 inch Hart barrel in a bolt gun. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
Reloading
Developing Load for 168 Berger New Brass vs Once Fired
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