denton
Member
Here are some QuikLoad estimates of muzzle velocity vs. peak pressure. In my experience, if you use your measured case capacity and actual COL, QLoad produces good estimates even though the author goes to great lengths to say that loads should not be used without testing, as he should.
In this table, I took the defaults for each cartridge. It's reasonable to assume that any error QL makes on one cartridge, it will also make on the others. So the differences between loads and pressures may be a little better than the absolute pressures.
The estimate for 7x57 at 55,000 PSI is right in line with my measured values at 56.6 KPSI.
I think that if you had three rifles, identical except for being correctly chambered in the three cartridges shown, and ran them all with the same bullet and the same pressure, then the wear, probability of a stuck case, and probability of catastrophic failure would be the same for all three.
Does this mean you can run the 280 at 65 KPSI, like the 270? Grown men can make their own decision about that. I wouldn't go nearly that high. Most of the 270 loads I've seen stay respectfully short of the 65 KPSI limit.
In this table, I took the defaults for each cartridge. It's reasonable to assume that any error QL makes on one cartridge, it will also make on the others. So the differences between loads and pressures may be a little better than the absolute pressures.
The estimate for 7x57 at 55,000 PSI is right in line with my measured values at 56.6 KPSI.
I think that if you had three rifles, identical except for being correctly chambered in the three cartridges shown, and ran them all with the same bullet and the same pressure, then the wear, probability of a stuck case, and probability of catastrophic failure would be the same for all three.
Does this mean you can run the 280 at 65 KPSI, like the 270? Grown men can make their own decision about that. I wouldn't go nearly that high. Most of the 270 loads I've seen stay respectfully short of the 65 KPSI limit.
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