Gamesniper19
Well-Known Member
For Extreme ELR - the miller calculation is lacking...agree
For 1500 yards its fine
Twist rates for elr?
- Thread starter RockyMtnMT
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For Extreme ELR - the miller calculation is lacking...agree
For 1500 yards its fine
It's not relevant to this discussion of ELR, but one caution about the Berger twist calculator: It does not include the adjustment for polymer tips. That's likely because Berger doesn't sell bullets with polymer tips. But if you're ever interested in comparing or estimating twist for bullets that do have them, I'd recommend the JBM calculator, which does include this adjustment.
https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi
Gamesniper19
Well-Known Member
Agree with the JBM data - another great resource
TXAoudadKlr
Well-Known Member
Chey-Tac is still around?? Hmm.
D
Deleted member 71114
Guest
There's a good amount of discussion listed in this thread as well as opinions. With that said how many here have had to shoot under a stressed environment of a competition in the 3000+ yard range with good success as Steve mentioned. This is huge compared to shooting in a comfort zone and when conditions are favorable to the shooter.
What works at 1760 not necessary works as well at 3500 just asking as we try to perfect the system and there seems to be a bunch here that quantify in this area.
Throwing it out there for those who voiced opinions on what justifies as far as the Miller theories if I used the configuration of the bullet and environmentals it states a 505 grain 416 is stable at a 8.5 twist and slightly over stabilized at 8, I would say this is overtwisted in todays shooters community versus not aggressive enough. The Berger system is just a generic user freindly guide that gets folks close in the zone.
So again I ask as we all strive for the upmost valid info - who here has pushed the 3500 yard under a stressed environment with valid success? Thanks and congrats for excelling to this level in accuracy.
Cheers
Osoh
JH
What works at 1760 not necessary works as well at 3500 just asking as we try to perfect the system and there seems to be a bunch here that quantify in this area.
Throwing it out there for those who voiced opinions on what justifies as far as the Miller theories if I used the configuration of the bullet and environmentals it states a 505 grain 416 is stable at a 8.5 twist and slightly over stabilized at 8, I would say this is overtwisted in todays shooters community versus not aggressive enough. The Berger system is just a generic user freindly guide that gets folks close in the zone.
So again I ask as we all strive for the upmost valid info - who here has pushed the 3500 yard under a stressed environment with valid success? Thanks and congrats for excelling to this level in accuracy.
Cheers
Osoh
JH
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Idaho Hunter1
Well-Known Member
What caliber is the choice one for that range?
D
Deleted member 71114
Guest
A few options
Osoh
Although we are generally looking at the ideal twist rates per caliber and construction/shape of a bullet. I would like to mention that the exit speed at which we are shooting the bullet at will also effect the exit RPM of the the bullet too. The 20 to 1 twist is not a ratio that is set in stone! It is the SG to get thru the TRANSONIC region that we are trying to achieve here. Also remember that the ideal SG is also effected by the density of the material too!
Simply put:
1) The twist rate sets up the rpm of the bullet at a given exit speed. The bullet is now a gyro.... If the ideal twist rate is at 20:1 for 3000fps we therefore will not need as much twist rate if the bullet is exiting at say 3300fps because the rpm of the said bullet is now 10% higher.
2) The 20:1 twist rate that is used is for copper alloy bullets which have a density of around 8.8. Bronze alloy is around 8.4, and heavy lead jacketed bullets are around 10. The higher the density of material the less twist rate that will be needed.... This is because the the resistance to a change in direction of a gyro is related to the mass and its distance from the spin axis (center of rotation) and its speed of rotation (RPM).
Remember too that these super fast Hyper stabilized twist rates are so the bullets can get thru the transonic region with a minimum of fuss. If we can keep the bullet above the transonic region ( Mach 1.2 ) we will not need such a high twist rate to keep the bullet stable in flight.
The twist rate you pick should be chosen by the JOB you are trying to accomplish. The twist rate for K2m is different from what is considered ideal for a 1000 yard bench rest F class shooter and is VERY different than what is needed for a hunter....
Simply put:
1) The twist rate sets up the rpm of the bullet at a given exit speed. The bullet is now a gyro.... If the ideal twist rate is at 20:1 for 3000fps we therefore will not need as much twist rate if the bullet is exiting at say 3300fps because the rpm of the said bullet is now 10% higher.
2) The 20:1 twist rate that is used is for copper alloy bullets which have a density of around 8.8. Bronze alloy is around 8.4, and heavy lead jacketed bullets are around 10. The higher the density of material the less twist rate that will be needed.... This is because the the resistance to a change in direction of a gyro is related to the mass and its distance from the spin axis (center of rotation) and its speed of rotation (RPM).
Remember too that these super fast Hyper stabilized twist rates are so the bullets can get thru the transonic region with a minimum of fuss. If we can keep the bullet above the transonic region ( Mach 1.2 ) we will not need such a high twist rate to keep the bullet stable in flight.
The twist rate you pick should be chosen by the JOB you are trying to accomplish. The twist rate for K2m is different from what is considered ideal for a 1000 yard bench rest F class shooter and is VERY different than what is needed for a hunter....
VLD Pilot
Well-Known Member
CheyTacs and SnipeTacs rule that territory. No doubt there in a league of there own.
VLD Pilot
Well-Known Member
Seems like for the .338, that formula is a bit off. 6.7 twist for solids in a .338 seems to me a little fast. I might go 7.5-7.75 but 6.75 seems too fast.
