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OK sorry, should have read more, moving along LOL
The end of Chapter 12 (pages 181-188) in the 2nd edition covers this topic (that of non-linear dispersion). Aside from the obvious factors such as wind and velocity, he mentions that "launch dynamics" (errors induced by the user, barrel whip, etc.) are another contributor of error that impart a velocity to the bullet, which cause dispersion to increase according to time of flight, and thus will tend to be increased in a non-linear fashion with increased distance (since time-of-flight of course increases non-linearly).
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I've read the 1st edition cover to cover, but have not yet update to the 2nd edition. I thought about the same exterior ballistic effects of barrel whip, but had no way to measure that without a real high speed camera.
I think, with me anyway, the user effects dominate these other effects.
I believe a combination of wind and shooter inexperience should be the main contributors in this case. So until I can go back out on a calm day with great conditions and take wind out of the equation it would be hard to determine any other issue. As one of the posts here indicate the 6.5 140gr. is still supersonic at 1400fps(way past my target) so I can say that the bullet is still stable. Hopefully next Friday I can go out again depending on the conditions and can have an update for all of you. Again, thank you guys for your support. Happy shooting
This is what I was thinking. A few degrees of cant will turn your 30moa adjustment into more like 28moa high & 2moa L/R...
Though my rig is accompanied with a level I have been told by some well known, very experienced shooters not to rely on it, instead to rely on my own ability to make sure my rig is level using sight, posture, and a 6th sense if you may. That being said, If I experience the same results on a day with perfect conditions and no wind I will add checking my level as one of the variables. Thanks for your input.
I highly doubt that a 140 gr amax out of a 6.5 CM is going subsonic at 850. I also shoot in Florida and have taken mine out to 1200 yards with 120 grainers and it still does fine, definitely not subsonic yet. The 140 will stay supersonic longer than the 120 with factory loads. Mine is a 24" barrel. I would say you either have wind issues, scope issues, ammo issues, or nut behind the bolt issues, but you definitely don't have subsonic issues. If it were a 308 with 150 or 168 grain maybe, but Creedmoor no freakin' way.
my $.02
My 270 with Factory 130 grain Ballistic Silvertips, 150 Grain Nosler ABLR hand loads and 165 grain Matrix hand loads are very similar out to 700 yards. Past that they really start to diverge. So, what you are seeing is IMHO, well kinda normal.
Have you double checked your Muzzle Velocity??? How about the true BC of the bullet (no, not the advertized BC)
Past 700 is when at least in my limited experience where the conditions really need to be dialed in
Do that at our matches and you will be screwed because we purposely put objects at angles against the back drop that make it look level which causes you to correct by your eyes or level your cross hairs with it and then you will miss. Level is level and there is no arguing that fact. Use the level it will make a pretty big difference at 1K. Spend some time reading the wind on a spotter while not shooting. Learn what its doing at certian spots down range by the mirage and understand your bullet will not be at your level by the time its half way down so there may be more or less wind up where the bullet it at. Other than that practice is about all you can do. I may have missed it but what size was your target? Ive taken my 308 to a mile on a 12"widex24" tall target and had 2 out of 20 hit on the target which I though was pretty good considering its a 308 and a small target width wise. 1mph difference in wind would cause me to miss the whole thing to the opposite side of where I was holding if I recall correctly. Make note of your shots, conditions for each one, what wind at you and what you thought was the wind down range. After a while you will be able to see patterns that you can easily learn from. The 6.5 Creed should not have any issues at 1k with factory ammo, I watch many shoot to that distance with great success with those same loads..
OP,
Right now, your analysis procedure is not organized enough to sort out anything.
You must call your shots to have any recognition for the origin of your error. Most of your bullets going all over the place only suggests the rifle was pointed in those places, that's to say, either you moved the rifle to those strike points before the bullets cleared the bore, or the sight was adjusted to strike at those points for prevailing wind
Here's an example of sights not adequately adjusted for wind: shooter calls the shot right-in-there but the shot hits at 3 o'clock. Here's an example of the shooter moving the rifle: shooter calls the shot at 9 o'clock and the bullet strike is indeed out at 9 o'clock.
Even by plotting both call and strike, looking for the meaning of the corollary, you may not always identify the source or sources of error; but, since all error originates with shooter inconsistency and/or incorrect counters for the effects on external ballistics, quick correction can still be made just by focusing on what is necessary to hit the target, i.e. properly pointing the rifle with consistent sight alignment, adjusting sights for wind, and pulling the trigger without moving the rifle utilizing smooth trigger control.
One more thing, get a spotting scope. Focus on the target and then turn the focus knob a quarter turn counter clockwise to see mirage at mid range. Learn how to determine wind velocity and direction from the pattern of mirage. This will help you even if you are just using the spotting scope to recognize a prevailing wind which is what you have zeroed for.
Right now, your analysis procedure is not organized enough to sort out anything.
You must call your shots to have any recognition for the origin of your error. Most of your bullets going all over the place only suggests the rifle was pointed in those places, that's to say, either you moved the rifle to those strike points before the bullets cleared the bore, or the sight was adjusted to strike at those points for prevailing wind
Here's an example of sights not adequately adjusted for wind: shooter calls the shot right-in-there but the shot hits at 3 o'clock. Here's an example of the shooter moving the rifle: shooter calls the shot at 9 o'clock and the bullet strike is indeed out at 9 o'clock.
Even by plotting both call and strike, looking for the meaning of the corollary, you may not always identify the source or sources of error; but, since all error originates with shooter inconsistency and/or incorrect counters for the effects on external ballistics, quick correction can still be made just by focusing on what is necessary to hit the target, i.e. properly pointing the rifle with consistent sight alignment, adjusting sights for wind, and pulling the trigger without moving the rifle utilizing smooth trigger control.
One more thing, get a spotting scope. Focus on the target and then turn the focus knob a quarter turn counter clockwise to see mirage at mid range. Learn how to determine wind velocity and direction from the pattern of mirage. This will help you even if you are just using the spotting scope to recognize a prevailing wind which is what you have zeroed for.
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Without running the numbers, my personal rule of thumb is that when dispersion jumps counter-intuitively beyond a specific distance, there's probably some sort of transonic effect at work. Another rule of thumb is that for a reliably stable POI out at the near-transonic region, it's best to load for a minimum of 1300fps at the target's distance.
Shooting at Sea Level makes all the Sonic/Subsonic issues just about as critical as they can get, unless one shoots at the Dead Sea level or out in Death Valley.
Finally, BC is not a constant value, but is dependent on actual velocity. As velocity drops, so does BC, usually (some shapes more than others); so bullets shed velocity faster and faster the slower they get (I.e. BC data for 142SMK). My own experience is also that as the trajectory angle gets steeper, effective BC drops even more due to pitch/yaw angle. The faster the twist, the more pronounced this effect becomes.
Whether or not these issues are at the root cause of your questions, retained velocities are adversely affected as altitudes drop. When I first shot my 260 at 1000yd, it was at roughly 6000ft ASL, and going over 1100yd was not an issue. I have never shot LR at Sea Level, but questions like yours don't surprise me very much. I would think that sonic transition velocities could be susceptible to influences as small as temperature and barometric changes at such low altitudes.
Greg
Shooting at Sea Level makes all the Sonic/Subsonic issues just about as critical as they can get, unless one shoots at the Dead Sea level or out in Death Valley.
Finally, BC is not a constant value, but is dependent on actual velocity. As velocity drops, so does BC, usually (some shapes more than others); so bullets shed velocity faster and faster the slower they get (I.e. BC data for 142SMK). My own experience is also that as the trajectory angle gets steeper, effective BC drops even more due to pitch/yaw angle. The faster the twist, the more pronounced this effect becomes.
Whether or not these issues are at the root cause of your questions, retained velocities are adversely affected as altitudes drop. When I first shot my 260 at 1000yd, it was at roughly 6000ft ASL, and going over 1100yd was not an issue. I have never shot LR at Sea Level, but questions like yours don't surprise me very much. I would think that sonic transition velocities could be susceptible to influences as small as temperature and barometric changes at such low altitudes.
Greg
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I didn't take the time to read all the posts but I would strongly add that after a bad long range session that levels questions as to whether the shooter or weapon system is at fault to fire a group at 100. This could possibly eliminate a scope problem.
What twist? 8? An A-Max at that distance should not be subsonic.There is no sense throwing bullets downrange at 1000 without much more close range workups of a good tight load.
If reloads, give the components and preparation.
Is it possible that the tips are being hurt when closing the bolt? Find another person with a 24 inch and same load and see what their experience is.
Short version is that if you can't find a equipment problem, it is either the shooter (to include wind). Good luck. Slow down and go closer and work up 100, 500. etc. same day, same conditions.
What twist? 8? An A-Max at that distance should not be subsonic.There is no sense throwing bullets downrange at 1000 without much more close range workups of a good tight load.
If reloads, give the components and preparation.
Is it possible that the tips are being hurt when closing the bolt? Find another person with a 24 inch and same load and see what their experience is.
Short version is that if you can't find a equipment problem, it is either the shooter (to include wind). Good luck. Slow down and go closer and work up 100, 500. etc. same day, same conditions.
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