ammunition, ballisticsI’ve read that the 357 SIG’s purpose as a caliber was to match the ballistics performance of the .357 Magnum. (Wikipedia mentions this, for example.)
What exactly would it entail for the ballistics to match, in terms of performance?
Does the 357 SIG really match this claim?
Given that both rounds are the same caliber (same diameter bullet - capable of firing identical bullets) matching would mean being able to launch the same bullet weight at identical velocities. The .357 Sig falls short of the .357 magnum in that regard, but not by very much. I would still call their ballistics “comparable”. In a 125 grain bullet (a common, and popular weight for both rounds) the .357 Magnum gets ~100-150 fps faster than the .357 Sig. These figures are debatable as there are numerous loadings for both, but in general the Magnum will run a bit hotter than the Sig.
It’s a judgement call, but I’d say the Sig matches the claim of having comparable ballistics, but falls short of having equivalent ballistics.
There is no practical difference in the available energy between these two rounds based on commonly available commercial loadings of these two cartridges.
The original post is a bit ambiguous; in firearm ballistics there are internal ballistics (how the bullet behaves prior to leaving the muzzle), external ballistics (how the bullet behaves as it flies from between the muzzle and the point of impact), and terminal ballistics (how the bullet behaves once it makes impact with the target, such as a block of ballistic gelatin). In terms of handgun ammunition, the most common measure I’ve seen to distinguish the relative efficacy of one cartridge versus another is knock-down power, which is a product of the muzzle energy, external, and terminal ballistics. Given that 357 SIG and 357 Mag use the same diameter bullets (indeed, they can use the exact same bullets), for the sake of argument we can ignore the questions of external and terminal ballistics and focus just on muzzle energy.
Muzzle energy is a computation taking into account the weight of the bullet and the speed at which it’s travelling when it leaves the muzzle. I went to CheaperThanDirt.com and looked up the muzzle energy values for the top six most popular loads in each caliber. The average muzzle energy for the two cartridges: 357 SIG is 501.23 ft-lbs, 357 Mag loads is 469.56 ft-lbs.
Again, this is a reflection of what are the most popular items sold at CheaperThanDirt.com right now (and customer preferences can certainly change). The greater case capacity of the 357 magnum certainly makes it possible to load it to shoot with more muzzle energy than a 357 SIG, but that doesn’t mean that one can make a the general statement that one is ballistically superior to the other.
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