With the low pressures and velocities, relative to PBs, is there really any such thing as "too fast" for air gun twist rates? I know on a PB if you sling a lead bullet, even with a jacket, with too much RPM it basically explodes into dust in front of the muzzle. I feel like such a thing is not possible with HPA, given the modest pressures and velocities.
Quote from: Spacebus on March 28, 2023, 08:27:09 AMWith the low pressures and velocities, relative to PBs, is there really any such thing as "too fast" for air gun twist rates? I know on a PB if you sling a lead bullet, even with a jacket, with too much RPM it basically explodes into dust in front of the muzzle. I feel like such a thing is not possible with HPA, given the modest pressures and velocities. A own a TJ .30 cal barrel in 1-11 twist. I tried to shoot .44.75 & 50 grain JSB pellets threw it from 800 to near 1000 fps ..... WILD SPIRALS !!!!!!!!!!!!!Absolutely non usable being only good for a likely long 140 grain + slug YES indeed Too Fast a twist rate !!
Miles, doesn't the Military use about 2.5 for a target SG?.... I know that 1.5 is probably the minimum, below which you can get excessive yaw and lowered BC.... but I understood that "overspin" did not become a serious problem until about 4 or 5, for good quality bullets?.... I mean, within any give calibre, bullet weights (and lengths) vary such that SG values could be anywhere from unstable (twist too slow for the longest bullets) to quite excessive (particularly if the longest ones are stable).... Is there an acceptable "range" of SG, starting at maybe 1.2 or 1.3 and up to what, before excess gyroscopic stability becomes an actual problem?.... maybe 3?....Bob