The definition of the speed of sound is the speed at which a pressure wave travels through a gas. It's the transition from supersonic to subsonic that destabilizes the bullet. Triple from the G31 during a classifier, 10 yards out.įrom what I've read, the accuracy problem is most acute when a bullet leaves the muzzle at just barely supersonic speed and drops back to subsonic before hitting the target. Running a 55 go to 77 speeds will not make it more accurate. The 77 grs are going slowing because they are heavier and have less case volume left for powder. However typical pistol distance doesn't reveal anything significant versus the rifle, where for example, 77gr (2,700 fps) bullets in an AR15 tend to be much more accurate than 55 gr (3,200 fps) bullets at 600 yards. 45acp is inherently more accurate than a 9mm. Speed is based on bullet weight and case volume, accuracy is most dependent on bullet design, which is why a hollow point 230 gr. They go right at about 1,420 fps and can run doubles on almost every stage. My handloads for that gun are a 125 gr Montana Gold JHP over 7.8 grains of BE-86 at 1.140" OAL. 357SIG for carry and shoot USPSA Limited 9mm Major. 45acps over the years, notably 200 gr FMJs to over 1,100 fps and 230 grs to just over 575 fps to make minor floor for IDPA SSP using my G21 and didn't notice any accuracy difference inside of 40 yards, but the minor floor stuff took noticeably longer to cycle the gun. You can make USPSA/IPSC major with a 230 gr. Sub 100 grain bullets will go alot faster, but the accuracy is bad to start with. 45acp where the 38 special will make about 1,200 fps with a 125 grain bullet. 45acp and 38 special are nowhere near the speed of sound, even the +P stuff barely makes 1,000 fps in a. This explanation makes sense to me but I wanted to check with the gurus at TFL to get your input. I recognize that there are probably ten other factors that will matter more to accuracy than this issue, but when you are aiming for perfection, every factor matters. Thus, it was explained, to have the most reliably accurate handgun ammo one should load some of the heavier calibers at subsonic speeds (i.e. It was further stated that rifle ballistics are in a different class here because they are going so much faster than the sound barrier that it's a non-issue. (Sound barrier is ~1100 fps depending on elevation and hand gun ammo is generally between 800 fps and 1500 fps.) And that bumping around the sound barrier can destabilize the bullet and reduce accuracy. The explanation was that handgun ballistics are such that you are only slightly above or slightly below the sound barrier. I have read in a few places that subsonic ammo out of handguns (namely 45acp and 38 special) is preferred by shooters needing the most precise accuracy (like bullseye shooters) because it is more accurate.
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