Definition of an unfamiliar term?
- Thread starter Topwater
- Start date
I’ve never heard it either, but Immike is probably right and he’s colloquialising lack of precession. Really the bullet should not precess at all if your barrel has enough twist for the pill. It’s still affected by spin drift, and it shouldn’t be precessing at any point in its flight path. I guess all bets are off when it goes transonic, and that may also be what he’s describing. He may be saying it’s “asleep” when it remains supersonic too.
I was always under the impression that it referred to a bullet stabilizing some time after leaving the muzzle. In other words not being stabilized at first but then settling down and 'going to sleep' somewhere down range. I believe Bryan Litz does not follow that path. Can't say I have seen evidence of it either since many of us shoot one rifle from 200 - 1000 yards in increments. If it were true at one of the varied distances (200,300,500,600,800,900,1000) there would be a drop off in accuracy unless it somehow happens when the bullet is traveling at it's fastest velocity. Which makes little sense.
Or the 40+ grains of powder slapping it's ass.
Could this be one reason why the short range bench rest shooters like short bullets with slow twists vs. long bullets and fast twists? I first heard the term "going to sleep" when I started shooting 6.5mm 140 grain bullets. The term "yaw" followed by "dampening" might have some application. My adventures with spinning gyroscopes showed me a 90 degree deflection upon application of a directed force (vector). Upon a unsolicited and derisive comment about bench rest shooting with my 6.5-06 I responded by telling them their stubby bullet pea shooters would be failures at 600 yards.
Logically, "non-linear dispersion" would not occur. An attempt to get an expense paid trip to some far off place by an attempt to prove this would end in abject failure. But longer bullets require faster twists and the axis of a long spinning bullet would not coincide with the flight path for several reasons. A sideways flying bullet would have real problems for any good ballistic results.
Logically, "non-linear dispersion" would not occur. An attempt to get an expense paid trip to some far off place by an attempt to prove this would end in abject failure. But longer bullets require faster twists and the axis of a long spinning bullet would not coincide with the flight path for several reasons. A sideways flying bullet would have real problems for any good ballistic results.
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Has he or any of the AB team revisited this since they have got into ELR shooting with cheytac based cases? I saw stuff with my 338 snipetac that I'd never witnessed with 7mm and under stuff. Like a 5/8"(best) group at 100 but still that at 300 and 1" at 600 yards.
300gr -.338 cal bullets, 400gr -.375 cal bullets do funky things compared to 30 cal and under.
go for the expense paid trip
Yes it is out there courtesy of Mr Litz with exhaustive tests using half a dozen cartridges / calibres. Simply buy a copy of Modern Advancements in Long Range Shooting Vol II and read the lengthy chapter entitled Angular Convergence. This reports of several dozens of tests involved firing many hundreds of rounds in which bullets passed through two targets - one at 100, the other at 300 yards - and the results (as measured in MOA values) compared. A possible reason as to how a shooter might (incorrectly) believe in this claimed phenomenon is hypothesized, but 'bullets going to sleep' as a myth remains exactly that.
That and its Vol I predecessor contain lots of other interesting material, mostly range-test based and although expensive are well worth the outlay. It's rare for anybody to spend the time, money, and ingenuity to test these sorts of things out these days.
What?
Would any dampening effect be similar to "going to sleep" ? Have dampening effects been disproven (making them mythical)? My thoughts are that dampening effects exist and they are termed "going to sleep" and the dampening effects get mixed up with "non-linear dispersion" or "non-liner dispersion". An offer to get an expense paid tip to some far off place to shoot off guns is attractive (always looking for a deal) but because my groups would not get smaller (a safe bet) this would have detrimental affects on my credit card. As soon as I can get a free read I will go through Vol II to learn more about the "convergence" stuff.
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Thanks, Rem06, for this reference. Apparently this theory has never been proven. At the very least, I now have a better understanding of the term.
the nice man has offered to pay expenses to show "non-linear dispersion" or "non-liner dispersion" or reduction of group size at extended ranges. I will carefully read the attachment again to see if I missed any references to "going to sleep" I did see stuff about marginal twist rates.
dcali
Bullet Maker
The technical term for it is “epicyclic swerve” and it is the spinning pitching and yawning motion of a bullet. Early in the bullet’s flight the yaw is larger and shrinks as the bullet travels down range. Hence “going to sleep”.
The impact of this motion is that the trajectory has a very slight helical-like shape (as opposed to just a smooth arc).
This phenomenon is often misunderstood to mean that rifles need to hit a certain distance before they hit peak accuracy. This is incorrect reasoning for many reasons, but it persists nonetheless.
Bottom line is that a bullet’s damped epicyclic swerve is of no practical importance to riflemen.
The impact of this motion is that the trajectory has a very slight helical-like shape (as opposed to just a smooth arc).
This phenomenon is often misunderstood to mean that rifles need to hit a certain distance before they hit peak accuracy. This is incorrect reasoning for many reasons, but it persists nonetheless.
Bottom line is that a bullet’s damped epicyclic swerve is of no practical importance to riflemen.
dcali
Bullet Maker
The short bullet/slow twist setup is preferred by short range benchrest because it minimizes aerodynamic jump, and therefore bullet dispersion. And since they have more need for hyper-precise groups than for wind bucking, they’re happy to give up ballistics for smaller groups.
At some range, that trade off flips and ballistics become a more important factor, which is why long range shooters prefer longer, heavier, lower drag bullets, and will give up some raw accuracy to get the ballistic benefits.
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