Flechette
Member
- Joined
- Oct 7, 2011
- Messages
- 481
I got a question regarding the ballistics of these two cartridges.
.357 is considered more powerful than a 9mm, but with modern powders there are 9mm loads that approach a .357.
For example, on Ballistics By The Inch a 9mm, 4 inch barrel Cor Bon 125 gr load yields velocities of about 1200+ fps whereas .357 124gr is about the same.
.357 jumps to 1300-1400 for a 4 inch barrel but barrel lengths are measured differently for a revolver versus a auto so a 3 inch barrel is probably a better comparison.
However, if we go to heavier bullets a 147gr 9mm gives 900fps and change whereas a 158gr .357 gives 1100fps. Much better performance!
What's going on here? I would think that .357 would not have such good performance against the 9mm for heavier loads as more gas would be lost through the barrel cylinder gap. A heavier bullet means more time in the barrel and thus more time for gas to be lost. I would think that a 9mm has the advantage when using a heavier bullet but it is the exact opposite.
Another bit of weirdness, Ballistics By The Inch has a section of tests precisely on revolver cylinder gap. For the Cor Bon .357 125gr DPX (http://www.ballisticsbytheinch.com/corbon2.html) the load underperforms itself when using no cylinder gap!
How can the exact same load lose performance when there is no cylinder gap?
.357 is considered more powerful than a 9mm, but with modern powders there are 9mm loads that approach a .357.
For example, on Ballistics By The Inch a 9mm, 4 inch barrel Cor Bon 125 gr load yields velocities of about 1200+ fps whereas .357 124gr is about the same.
.357 jumps to 1300-1400 for a 4 inch barrel but barrel lengths are measured differently for a revolver versus a auto so a 3 inch barrel is probably a better comparison.
However, if we go to heavier bullets a 147gr 9mm gives 900fps and change whereas a 158gr .357 gives 1100fps. Much better performance!
What's going on here? I would think that .357 would not have such good performance against the 9mm for heavier loads as more gas would be lost through the barrel cylinder gap. A heavier bullet means more time in the barrel and thus more time for gas to be lost. I would think that a 9mm has the advantage when using a heavier bullet but it is the exact opposite.
Another bit of weirdness, Ballistics By The Inch has a section of tests precisely on revolver cylinder gap. For the Cor Bon .357 125gr DPX (http://www.ballisticsbytheinch.com/corbon2.html) the load underperforms itself when using no cylinder gap!
How can the exact same load lose performance when there is no cylinder gap?