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Old February 24, 2020, 01:54 PM   #51
hounddawg
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I'd be willing to bet that it is more this shooters ability to hold a .5 MOA than the rifles ability to shoot .5 MOA as yardage increases. Just speaking for myself, others may be shooting gods that are only held back by the ammo and rifle

I say that becasue recently one of the club members was selling one of his rifles, a high end custom built rifle. In his hands the rifle shot .5 or below out to 800, when I shot it my groups were not much better than my garage builds. I did fall in love with that Shehane tracker stock though and plan on retrofitting at least one of my rifles with one soon
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Old February 24, 2020, 06:10 PM   #52
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I'd bet most F class competitive shooters can easily hold inside 2/10ths MOA and less than 10% will hold well inside 1/10th MOA. The rifle is artificially supported and heartbeats won't cause much LOS wiggle at all.

Conventional prone competitors using slings can hold inside 1/2 MOA when the wind isn't buffeting them around.

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Old February 24, 2020, 07:12 PM   #53
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I'd bet most F class competitive shooters can easily hold inside 2/10ths MOA and less than 10% will hold well inside 1/10th MOA. The rifle is artificially supported and heartbeats won't cause much LOS wiggle at all.
And I will bet you are wrong, this isn't five or ten shot short range benchrest

In F class anyone who can shoot 1 minute of angle 100% of the time would get a perfect 200 score every target, the ten ring on the @300, 600, and 1000 is 1 MOA. F class at 800 yards uses the 1000 yard target so the ten ring is 10 inches or 1.25 MOA.

2019 mid range national championship

winner had a 1794 aggregate. Six shots out of 180 were outside one MOA. 61 were outside .5 MOA. 10th place guy dropped a average of 5 shots out of ever 60 outside 1 MOA. A far cry from your claims of .2 hold and wind calling

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Old February 25, 2020, 07:58 AM   #54
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The hold area I'm referring to is where the point of aim is. Not the size of shot hole groups.
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Old February 25, 2020, 08:25 AM   #55
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The hold area I'm referring to is where the point of aim is.
and how did you measure the point of aim to come to that conclusion ?

I suggest you read Jim Owen's book Sight Alignment , Trigger Pull and the Big Lie. Pay attention to Chapter 9. Page 143 to be specific where he describes a marksman with a 6 minute hold being able to keep his shots within a 36 inch circle at 600 yards

Using Owen's definition my own ability is a .5 MOA hold @100, 3/4 MOA hold at 300, 1 MOA hold @600, and a 1.5 MOA hold at 800 judging by my average group sizes. I am below average compared to the top F class shooters who have 1 MOA or less holds out to 1000
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Old February 25, 2020, 09:37 AM   #56
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and how did you measure the point of aim to come to that conclusion ?
If the scope's reticle (the point of aim) wiggles around inside a 5 inch diameter area on a target 1000 yards downrange while you're slung up in prone without artificial support, your hold area is a half MOA.
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Old February 25, 2020, 11:26 AM   #57
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A distinction has to be drawn between your ability to hold a sight picture (what I believe Bart is referring to) and your ability to get the shots to place that tightly on an actual target, especially at long range where wind, gun and ammunition limitations, bullet drop and even bullet-to-bullet variation all have effects you are challenged to resolve at 100 yards. You can prove your hold by shooting at 100 yards with a load suited to that range to eliminate those variables. When things are going well, shooting knots or sometimes bugholes at that shorter range isn't wildly uncommon, and I think we've all experienced that when our gun and loads were working well together. This article describes a fellow who apparently can do it consistently. Most benchrest competitors hold sight pictures at that level of precision regularly. I don't know how close to that F-class shooters, specifically, do on hold, but don't see why they should be too much worse and Froggy shows they don't have to be worse.

I recall in Mid Tompkins's Long Range Firing School he told us 1000 yard wind changes faster than you can dial in adjustments finer than about half-moa, so he felt having sights with adjustments finer than that was pointless. If he picked up on a quarter moa shift by watching where the other competitor's spotters came up, he used Kentucky windage rather than sight settings to correct for it. And he was talking about Palma rifles with open sights. So, small moa numbers are discernible to the eye and, in the case of Tompkins, for one, even possible to correct hold for, though position and trigger control and equipment and ammunition that are all solid as a rock all have to be present for the shooter to be up to the task of getting the bullet where he wants it.
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Old February 25, 2020, 11:57 AM   #58
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my rule of thumb is groups on windless cloudy days at 100 show what the rifle/ammo is capable of with me behind it. Group sizes at 600 and farther with wind and mirage show what the flaws in my environment reading and hold. When the group sizes at 800 and 1000 are the same size as the group sizes at 100 I am squeezing everything I can from that rifle/ammo and it is time to upgrade the rifle/ammo. If they are larger I need to improve my technique
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Old February 25, 2020, 12:56 PM   #59
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If groups at 100 yards are averaging half an inch, they won't be that size further downrange.

Muzzle velocity spread causes groups to change their angular size with range. A 50 fps spread from a 308 Win can cause a 1/10th MOA vertical spread at 100 yards. At 1000 yards, it's 2 MOA. This assumes there's no compensation for velocity spread by the barrel vertical vibration shooting slower bullets at greater angles to the line of sight than faster ones.

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Old February 27, 2020, 09:45 AM   #60
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Originally Posted by hounddawg View Post
When the group sizes at 800 and 1000 are the same size as the group sizes at 100 I am squeezing everything I can from that rifle/ammo and it is time to upgrade the rifle/ammo. If they are larger I need to improve my technique
There's a flaw in this reasoning. Groups are never the same extreme spread dimension in inches at all ranges for a given barrel profile. Nor subtend the same angle.

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Old February 27, 2020, 07:14 PM   #61
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Newton's first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force.

Things like wind reading, trigger control, breathing, and recoil management can only be developed with practice

Best series ever for anyone who wants to learn how to precision shoot at long range

https://precisionrifleblog.com/2015/...erall-summary/
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Old February 28, 2020, 01:44 PM   #62
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There's a flaw in this reasoning. Groups are never the same extreme spread dimension in inches at all ranges for a given barrel profile. Nor subtend the same angle.
Yep. Well known fact.
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Old February 28, 2020, 04:50 PM   #63
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All bullets from the same lot will not have the same ballistic coefficient so even if they leave at the same velocity, they will string vertically. Moreso as range increases.
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Old February 28, 2020, 05:00 PM   #64
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As Litz points out, because group spread includes a lateral drift velocity that remains fairly constant (too slow for drag to affect it appreciably during TOF), it has a tendency to be proportional to TOF in a zero wind situation, and more when the air isn't perfectly still. That TOF increases for each successive 100 yards of bullet travel, so the addition to the MOA of the group is proportionally greater at the end of each 100 yards.
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Old February 29, 2020, 05:10 PM   #65
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wow this thread went sideways all good, it has been an interesting read.
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Old February 29, 2020, 05:56 PM   #66
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Originally Posted by Unclenick View Post
As Litz points out, because group spread includes a lateral drift velocity that remains fairly constant (too slow for drag to affect it appreciably during TOF), it has a tendency to be proportional to TOF in a zero wind situation, and more when the air isn't perfectly still. That TOF increases for each successive 100 yards of bullet travel, so the addition to the MOA of the group is proportionally greater at the end of each 100 yards.
This is why a given cross wind speed only in the first third of range to a 1000 yard target causes more than 2 times the lateral bullet drift on target than the same cross wind only in the last third.


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Old March 2, 2020, 11:42 AM   #67
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Yep! Exactly. You always hear the argument that wind drift should properly be called wind deflection, but the reality is often a mix of the two. In the case of the blue line, you have pure deflection, but for the purple line, you have deflection up to 330 yards, followed by drift due to the lateral velocity already imparted to the bullet by the deflection for the rest of the distance to the target.

Since drag increases with velocity, more drift is imparted by deflection when the bullet is going faster, and that's near the muzzle.
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