C'mon, guys. (accuracy claims)

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There's a perpensity to quote accuracy at the smallest group size ever fired. Which means that if one's shot 50 groups, the rifle, ammo and shooter do that well 2% of the time. Nobody knows what happened the other 98% of the time.

Rarely does anyone shoot at least 20 shots per test group. Statistically speaking, the size of a 5 shot group measured between centers of widest shots has only a 55% probability of being what all shots fired will go into.
 
Accuracy is pretty overrated in all practical senses.

2 inches at 100 yds is good enough to kill deers and most other game.

6 inches at 25 yards is good enough for self defense.
 
Bart B., if a rifle could be proven to be capable of 1/4 MOA, a load capable of 1/4 MOA and a shooter capable of holding a 1/4 MOA, under "perfect" conditions, wouldn't the system consisting of rifle, load and shooter be 3/4 MOA?

:)
 
After half a year of learning, my savage 12FV could generally product 1/2" (extreme center to extreme center) 5 shot groups at 100 yards using handloaded ammo and match bullets from hornady. occasionally it would do worse, occasionally it would do better, but on AVERAGE it would do 1/2" OR JUST MAYBE 7/16.

Now by comparison. the 6PPC rifles some of the folks at my club have will routinely produce things in the .2's or so. I know, because I've see their targets. I've even seen groups i the .1's. (From them, not from me)

They spent several thousand getting there.

I took the receiver off that 12FV and converted to a match 6PPC barrrel and see promise of 3/8" groups (did one today) once I get sufficient experience. I've heard of factory savages (and other brands) that get 1/4" groups, but those are rare.
 
1858's question:
Bart B., if a rifle could be proven to be capable of 1/4 MOA, a load capable of 1/4 MOA and a shooter capable of holding a 1/4 MOA, under "perfect" conditions, wouldn't the system consisting of rifle, load and shooter be 3/4 MOA?
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In my opinion, close; very close.

One has to put the rifle and ammo into the same boat. One can't shoot without the other. So you end up with a half MOA rifle and ammo.

So a shooter can hold 1/4 MOA; pretty rare in my opinion as the best prone shooters on this planet hold about 3/4, maybe 5/8 MOA in rare instances, and try to get their shots off inside a 1/2 or 3/8 MOA area. If they've got a 1/2 MOA rifle and ammo, the groups should be a third bigger than their holding area or 1 MOA. So much for simple mechanics.

The last straw is one's ability to hold the rifle exactly the same way for each shot then hold still while the bullet goes down and out the barrel do recoil during this time doesn't move the muzzle axis. No flinching allowed. No finger flicking allowed. No aiming eye blinking allowed. These things, if done, cause the barrel to jump off its aiming point to some degree.

So one ends up shooting a group a bigger than his holding area. Maybe a third to a half bigger.
 
When dealing with internet claims of accuracy, I find the following glossary helpful:

group: three shots from a warm barrel

flyer: shot that would make a group too large

shoots MOA: once shot MOA

until the barrel heats up: until bullets pass down the bore

shoots MOA all day long: I stop shooting when I get a big group

if I do my part: if I get lucky

yards: feet

;)
 
Regarding how group sizes combine (e.g. the 1/4 MOA shooter with 1/4 MOA ammo and a 1/4 MOA rifle), it's not additive. Sometimes one source of error will act to counteract another; for instance, the shooter might pull slightly right at the same time that the rifle happens to shoot a bit left, ending up with errors ameliorating each other. In order to calculate the expected effects of adding two sources of error together, you have to assume the bullet impact distribution introduced by the rifle and shooter are both normal distributions, so that you can use root-sum-of-squares analysis. (This link explains how it works; you'll need to scroll down a bit.)

To calculate the Root Sum of Squares, you just take each source of error, square it, add them together, then take the square root of the results:

errors.png

So for a shooter who can hold 0.5 MOA shooting a gun that can hold 1 MOA, you get a combined accuracy of 1.1 MOA:

square root(0.5^2 + 1^2) = square root(0.25 + 1) = square root(1.25) = 1.12


Pretty sure I've got this right; please let me know if I've messed up the math.
 
No lies here, went to a gravel pit the DNR says is fair game for target shooting and spent 2 boxes of brass. Was shooting 100-200yds - Win Mod70 7mm-08 with Nikon 3-9x40. Had IPDA-style targets with a circle drawn dead center and got a 6" group of 20 some shots and another target a 5 shot at 200 that was 3.5" or so, about my thumb.

Laying down in the snow, with jacket for a bipod rest. Nice sunny summer day, low winds, unlike today being 20 deg and 5-15mph wind ... I could probably prone on good concrete and pad, a 1.5-2" group at 100. Average will still sit around 3-4 I imagine. Even with a high end AR, that's about my best I think. I'm young though, so maybe I'll age well.

I don't own a high-end bolt rifle, both mine are hunting rifles, but even with my 7mm Rem Mag out to 400-500 with a 4-16x50 I can hold paper plates at 400. Hunting rifles, and book reloads that shoot pretty flat from 200 to 400.

I can hit vitals on most big game, and that's all I ask of my guns. I'd like to trick out a 22-250 or wildcat load for target and varmit, and maybe then I'll demand a little more from my rifles.

In process of building my own AR15 and won't comment about performance with trying other's guns.
 
Candiru, as interesting as your link is, I'm not convinced that the methods described apply here. Each shot in a group can be used to calculate a value such as "average distance to center". This is shown as ATC on the targets in my earlier post. In this case, each shot is statistically significant and in a sense carries equal "value". However, if in a 20-shot group, 19/20 shots fall within 1/2 MOA, but one shot is out at 1 MOA, the group size is 1 MOA. In other words, group size is not a statistical average because the one shot out of the group (flyer) doesn't carry equal value.

Consider my example in the earlier post of the 1/4 MOA rifle, 1/4 MOA load and 1/4 MOA shooter. Assuming all three components perform at 1/4 MOA, a shot could be to the right of the POA by 1/8 MOA (due to the shooter) + 1/8 MOA (due to the barrel) + 1/8 MOA (due to the load). If a shot to the right at + 3/8 MOA is possible (max error to the right), then a shot to the left by the same amount is also possible (max error to the left). This would mean that if all three systems perform to their respective accuracies, all shots should statistically fall within 3/4 MOA. Naturally, there'll be a Gaussian distribution around the center of the target and there will be groups smaller than 3/4 MOA, but the system should consistently be a 3/4 MOA system.

I'm curious as to what others think about this. I could be way off.

:)
 
1858 said:
Candiru, as interesting as your link is, I'm not convinced that the methods described apply here. Each shot in a group can be used to calculate a value such as "average distance to center". This is shown as ATC on the targets in my earlier post. In this case, each shot is statistically significant and in a sense carries equal "value". However, if in a 20-shot group, 19/20 shots fall within 1/2 MOA, but one shot is out at 1 MOA, the group size is 1 MOA. In other words, group size is not a statistical average because the one shot out of the group (flyer) doesn't carry equal value.

Consider my example in the earlier post of the 1/4 MOA rifle, 1/4 MOA load and 1/4 MOA shooter. Assuming all three components perform at 1/4 MOA, a shot could be to the right of the POA by 1/8 MOA (due to the shooter) + 1/8 MOA (due to the barrel) + 1/8 MOA (due to the load). If a shot to the right at + 3/8 MOA is possible (max error to the right), then a shot to the left by the same amount is also possible (max error to the left). This would mean that if all three systems perform to their respective accuracies, all shots should statistically fall within 3/4 MOA. Naturally, there'll be a Gaussian distribution around the center of the target and there will be groups smaller than 3/4 MOA, but the system should consistently be a 3/4 MOA system.

I'm curious as to what others think about this. I could be way off.

:)
Click to expand...
Actually you both are.

Different statistical analyses, but both appropriate.

Candiru posted Root Sum of Squares, which does take into account the cancelling effect of the variances, to get a realistic estimate of accuracy.

You are looking at worst case, (while eliminating the outlier).

So the worst case of the shooter in your example is actually 3/8 MOA from POA (0.375).

Using your inputs you'd have ((1/8^2) * 3) ^ 0.5 or roughly 1/5 MOA (0.2165).

Now each is realistic assuming perfect parameters, Effectively what you have is a bell plane (a 3 dimensional bell curve) where the majority of shots are contained within the main bell plane body, but with outliers towards the planes tails. You can do this with a simple bell curve by taking a scalar measure of the linear displacement from POA. Chances are if you did this and assuming normal and independent distribution of error in the shooter, rifle and ammunition then ~95% (2 standard deviations) of the shots would be contained in a 1/5 MOA circle and the remainder in the 1/5 MOA to 3/8 MOA donut.

Does this make sense...?
 
Candiru and others on his comments.....

I'm a beliver that when the rifle fires at the far edge of one's holding area, once in a while the bullet will get to the target as far as its accuracy from the rifle that fired it makes it go. So all those square (and all other shaped) roots mathed together puts it in engineering terms but the reality is that on very,very rare occasions, they all add up in the same directions.

All of which explains why some shots fired when the extreme limits of holding end up dead center and others fired when aimed at the same place land where the total of all variables add up in the same direction. That dead center shot from the widest call happens when all the variables subtract from the aiming point's distance from center.

Oh, one other thing; there are no fliers. Every bullet goes where it was intended to. Something in the entire shooting system (rifle+ammo+shooter+environment) added up to its impact location. It's the sum of all possible variables of each part of the system at their maximum values that just happened to add up in the same direction. Folks who don't understand this call them "fliers."
 
However, if in a 20-shot group, 19/20 shots fall within 1/2 MOA, but one shot is out at 1 MOA, the group size is 1 MOA
Click to expand...

I submit that in that instance, for practical application, not record-setting, that would be a 1/2 MOA Combination. The error is human most of the time, so one might say in this case that the shooter is 1/2 MOA capable 95% of the time. Or consider it as we normally shoot groups of five. That'd be 3 at .5 MOA, 1 at 1 MOA for an average of .625 MOA. That's pretty consistent for the real-world.

To say that that is a 1 MOA group would be like saying a drag car that made 19 runs averaging 7.832 and one run at 8.076 runs in the 8's. One bad run does not make the other 19 count for nil. It simply brings the average to 7.844 seconds.

When I chrono my loads, I don't use the fastest or slowest of the batch to determine my actual velocity, but the average of 10, 20, 50, or however many I measure. Obviously, the more shots I make, the closer I am to a reliable median velocity.

Just as insignificant in the aggregate total are our smallest groups, so are the largest. We take an average, not the smallest, not the largest.

All that said, I'm not a BR guy. I've just done my share of research on the subject. I'm a vamint hunter, so I'm quite happy with my two rifle/load combos that are reliably minute of praire dog to 300 yards when the weather cooperates. Turning the diseased little vermin into mist from 3 or more football fields away is good enough for me :D
 
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I have a beretta tomcat 22 that I shot a hog in the head with once. It was anywhere from 12 to 700 yards if I remember correctly. He got thrown 20 feet from the impact. :D
 
The last time I went to the range, I did shoot a 2 MOA with my bone stock M1 Garand. It has been my personal best thus far. I was using reloads-168 grain Hornady BTHP. Using milsurp ammo, my groups open up to about 3.5-4, but I am working on that. I have a 'coach' who is helping me.

I think it is funny when people claim they get unbelievable accuracy claims from old rack grade Garands. I get reasonable accuracy from my rifle, but it does have a good barrel-1.5 throat a little over 1 on the muzzle.

I do plan on shrinking my groups, but isn't that part of the fun :D.
 
I once shot a .250" group with a WASR 10/63. What do I win?



(Of course ... it was two shots with the rifle fully benched in a vise and it was at 25 yards. But still ... I shot a .250". I don't care of you believe me or not. So there! :p)
 
i find it entertaining when people post a picture of their "awesome group"...but in the picture, the group is like 4 or 5 inches from the bullseye...where im from, they say your consistent, but you consistently miss lol
 
pikid89 said:
i find it entertaining when people post a picture of their "awesome group"...but in the picture, the group is like 4 or 5 inches from the bullseye...where im from, they say your consistent, but you consistently miss lol
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now don't read too much into that

a lot of my groups get trimmed down and rotated from the orientation on the target they were fired. Sometimes the aiming point is cut off, sometimes this distance was all elevation on a rifle zero'd much farther out, Sometimes the group was fired during load development (I never zero a rifle based on shots only groups), in some cases it's a different load than the rifle is regulated for (changing loads can cause MASSIVE POI shifts)
 
Ha Ha, I'll add a couple things plus some emphasis to Candiru's glossary:

yards: feet [Most common and most important one]

group: three shots from a warm barrel

flyer: shot that would make a group too large

shoots MOA: once shot MOA without the flyer(s)

until the barrel heats up: until bullets pass down the bore

shoots MOA all day long: I stop shooting when I get a big group

if I do my part: if I get lucky

I once did: I once dreamt it in a dream, or wished it to be true.
Click to expand...

I really object to the "all day long" thing - I know it's meant as an obvious exaggeration; but the extent taken literally, it just ain't happening, even from the best shooters. When you've been shooting more than an hour or two, your calm steady focus is nearly impossible to maintain for long periods of time, and I promise you, getting 5-shot sub-1 MOA groups without flyers requires calm steady focus - from ANY rifle, with any setup, short of a vice/ransom setup.
 
i find it entertaining when people post a picture of their "awesome group"...but in the picture, the group is like 4 or 5 inches from the bullseye...where im from, they say your consistent, but you consistently miss lol
Click to expand...

Grouping is paramount to accuracy. You can always change your POI. I've watched alot of guys try to do the reverse, making scope adjustments after each shot. You'll never get zeroed that way. I use 5 shot groups for accuracy testing, 3 shot to zero the optic (I want to use up barrel life killing vermin, not shooting lots and lots of tight groups). My .17 rem is zeroed at 200 (as are most of my rifles), my .220 Swift at 250. They're both quite high at 100.

Even in the BR world, there are different ways of scoring. One type is x-ring, the other is group size.
 
I've always used a few five-shot groups as a test of the rifle itself. After I'm satisfied with it, I don't bother any more. Three-shot groups tell me what Bambi or Ol' Wily's gonna learn the hard way.

I ain't much on picking flypoop out of pepper...
 
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