Well a 150-220 grain bullet moving at 1000 fps could do far more than hurt a fly, subsonic bullets kill on a regular basis.
Recently the NRA of the UK had to reign in target shooters who were loading the .308/7,62 to maximum pressure levels in order to maintain supersonic velocities at 1,200 yards for their longest range matches. Transonic effects were the issue.
All-flying control surfaces are advantageous for supersonic aircraft because boundary layer effects are decreased at high Mach number. Moving the trailing edge of the tail has little effect, because the shock wave from the leading edge is so strong. Control is better accomplished by moving the leading edge, which reorients this shock wave.
The first US supersonic aircraft design, the Bell X-1 rocket plane, revealed that the formation of a secondary shockwave at the line of interface of the stabilzer and elevator caused loss of elevator control. The plane was altered on the runway to use is attitude control as its elevator with the elevators locked down to move with the stabilizer as a unit.
The Russians hadn't caught on to this and many Mig pilots died because the Mig-15 did not have the all flying tail of the F-86. The F-86 could maintain elevator control in high speed dives with trans sonic excursions, the Mig-15 elevator locked up and plowed up real estate.
The British liked to claim the US stole the idea from them, since they'd discovered the same factors in a supersonic missle design not long before, but the engineers with the X-1 project discovered it on their own.
The all flying tail isn't used because of any slight improvement in control, its used because separate elevators were completely useless at supersonic speeds.
edit to add
Before I forget, the F-102 originally didn't have the wasp waist, it was limited to short unsustained supersonic sprints, the F-102B was the result of lengthening the fuselage to add a second seat and while they were at it they incorporated the wasp waist to improve performance.
The F-102B became the prototype for the F-106, which due to its wasp waist became the premiere supersonic interceptor of its day, and served for decades.
I don't think Gunner (correct me if I am wrong) is saying that the direction of drift changes. Just that there is a throw-off due to barrel motion that starts the bullet off to the left of the point of aim.
Cheers,
Keith
Well I was confused earlier, due to my thoughts going to the lefthand Enfield twist, which resulted in my getting the whole effect backwards.
The exact cause of the lateral jump isn't given in the literature, and in earlier mentions of this phenomena jump was not mentioned at all near as I can remember.
Lateral jump is given in some sources as due to a muzzle whip up and opposite to the direction of twist, but atmospheric jump is another matter, both taking place as transitory effects at the muzzle.
Not sure about the following, or if it matters.
The possion effect is described as falling off a cushion to one side, usually in the direction of twist.
Seems to me that with the velocity and inertia of the bullet acting against a downwards force the magnus force might act as a pencil point pushed down in a slick metal cylinder resting on a table top, the cylinder can't move down so the force slips off to one side pushing the bullet to the oposite side.
The Magnus moment can relocate, the Chinese (Taiwanese)studies I looked at mention it moving to the boat tail of a SOCBT bullet, which is the most common match and long range bullet type in use.
Ran across some similar experiments by a French arms manufacturer, but can't access those yet.
Well the main question was if theres an explanation for bullets printing a tighter horizontal grouping in terms of MOA at 200 yards than at 100 yards.
The few reliable sources seem to indicate that this occurs when the barrel is relatively light for the power level of the cartridge such as in the case of the 18,000 round test firing of .50 guns, which appears to have been documented at the time if those test results can be accessed.
Printing a smaller group in the vertical, in either actual measurement in inches or in MOA, at longer ranges is not in question, thats been too well documented and observed to deny and the answer as to why has been well researched and explained in terms of compensation. Generally this required a long slim barrel and a fairly powerful cartridge with bullets in the 175 to 215 grain class. The SMLE exhibited the effect most strongly of any rifle I know of, the No.4 with heavier barrel and stiffer receiver exhibited it as well but to a much lesser and less consistent extent.
The SMLE compensation factor kicked in most noticably at ranges over six hundred yards. Whether some rifles exhibit compensation at 200 yards is still a question.
PS
Only reason I still experiment with the Enfields is because of the often weird accuracy effecting features of these rifles. They can be made to shoot with remarkable precision, but you really have to work at it.
I have far more accurate and consistent rifles, these have ended up hanging on the wall gathering dust or being traded off or given away, since hitting well with these is no challenge.
Since I've found out about the 1903 Springfield's odd lateral jump I'll probably find I now just have to have one.
A PPS
The bit about an indented surface increasing muzzle velocity does make sense.
Townsend Whelen mentioned the improved performance of the .30-40 when using a commercial match bullet which had two lube grooves. Lube proved to offer no advantage with this bullet, since no lube of the day could hold up to the velocity and pressure levels, but the grooves reduced bore friction. The same effect has been noted when hard cast zinc alloy bullets are used without lube. A bullet cast of the Zinc alloy weighed aprox 60% what a lead bullet from the same mold would weigh, and had most of the qualities of a FMJ bullet. The military used similar bullets to compare the resistence of armor plate alloys because of its consistency.
The unlubed Zinc bullets could be propelled to higher velocities with lower pressures since the empty lube grooves reduced the surface area in contact with the bore.
