Effect of Various Error Factors on Accuracy

[Oldblades]

Mike,
Been meaning to mention something to you for a while now. When I bought my first air gun, I found a youtube video that I thought was just awesome. Just a through scope view shooting X after X.
 Found myself saying out loud many times "a little more up" "a little further over" Had trouble finding it after that to watch it again.
Didnt realize until last week that it was you.
So now I can tell you that you were right in your holdoff more times than I was. 

Then about 3 weeks ago, I saw a video of a concept that I thought was waaaaayyyy ahead of the game using a breech block. Again, late last week I saw it again and realized whos video and concept that was.
Should have known by now.

Good luck at the Nationals Mike. Show those world champs that the only thing they have on you is more money to travel with!

[michaelthomas]

Tom, I'm only shooting the 15.9's because I have never found any 18's that would shoot better.

Jeremy,  you're fortunate to be able to shoot in Grants Pass.  That's a really nice place, and a nice bunch of guys to shoot with.  I was up to visit a few months ago, and had a great time.  Got to shoot indoors and out.

Scott....I'll do my best.   

Mike

[Oldblades]

This is such a good thread, it deserves a bump.

Been learning a lot these days about pellets and their various (and still confusing) tendencies in the wind. Shooting a lot of JSB/AA pellets from 7.3 to 10.(?) in the wind to see what they all do in different angles and wind velocities.

Is there a way to see what the BC of the pellets is at the decreased speeds downrange?
 The 7.3s run out of gas pretty quick in anything but calm/near calm out of a low power gun (about 700), while the heavies act like a old fullback. (coach if you need 2 yards I'll get you 4. If you need 10 yards, I'll get you 4).

What really interests me is guys shooting at 100, much of what the topic of this thread is about. Drift, velocity at different ranges, etc.
But what happens to the ballistics coefficient of a pellet at those ranges out at 50 and 75 yards?

[Motorhead]

This is such a good thread, it deserves a bump.

Been learning a lot these days about pellets and their various (and still confusing) tendencies in the wind. Shooting a lot of JSB/AA pellets from 7.3 to 10.(?) in the wind to see what they all do in different angles and wind velocities.

Is there a way to see what the BC of the pellets is at the decreased speeds downrange?
 The 7.3s run out of gas pretty quick in anything but calm/near calm out of a low power gun (about 700), while the heavies act like a old fullback. (coach if you need 2 yards I'll get you 4. If you need 10 yards, I'll get you 4).

What really interests me is guys shooting at 100, much of what the topic of this thread is about. Drift, velocity at different ranges, etc.
But what happens to the ballistics coefficient of a pellet at those ranges out at 50 and 75 yards?

Think Badminton shuttlecock    your typical Diablo skirt pellet by design is draggy and has a non linear  deceleration with time in flight and distance traveled.
BC at range is not very good and gets worse quite rapidly.

[Oldblades]

Think Badminton shuttlecock    your typical Diablo skirt pellet by design is draggy and has a non linear  deceleration with time in flight and distance traveled.
BC at range is not very good and gets worse quite rapidly.

Thats the part that amazes me about some of the groups at 100 I see here.
 Its a wonder that these things can hit paper at all, even with a excellent shooter at the helm.

[Tomg]

Even if the trajectory and BC goes down the drain as it flies out there, like a lead badminton ball. It does so the same way, every time.
So if the shooter have a gun that can deliver repeatable shots (fps) within a reasonable ES, and the shooter is applying his skill the same way every time, groups should be good. Barring any mosquito farts and stray el nino shenanigans.

[rsterne]

Actually, the BC of our pellets is much worse at 900-950 fps than at 500.... and for many pellets peaks in the 750-850 fps range.... I'm working on that, hoping to develop a much better drag model.... Michael already has a lot of the data for the JSBs in the velocity range he shoots.... The new LabRadar Doppler Radar will be a huge boost for determining how the drag changes as the pellet slows down....

Bob

[WeeHeavy]

I was going to ask about LabRadar for a purpose such as this. Seems that if it is recording multiple data points as the projectile travels, it would be perfect for calculating very accurate BCs. Doubt I will be getting one, but I will certainly be paying attention to any one who does. 

[Oldblades]

Thats the first I have heard of LabRadar. Looks like a pretty cool new toy for the lovers of testing.

The question came up in my head regarding the different weights after now getting seriously into playing with speeds on a gun, and looking at extreme spreads. It seemed that ES at the target would be as important as at the muzzle.
 
For some reason, I always seem to have a tendency to equate ballistics to a football quarterback throwing a pass at different speeds, trajectory, and distance. I guess its because its easier to see the effects.

 

[PakProtector]

If I want good data it will cost me. Since I don't have enough, I need a way to perhaps pay for a little of it. If I see a crowd-funding site tied to Bob I'd send money... Then all we need is a small handful of folks to see it too...LOL
cheers,
Douglas

[Bill G]

Bob would be the right guy to have one that is for sure.  got a link, I'm in.

Bill-

[Tomg]

How much are those?

[WeeHeavy]

$559.00 but it looks like they are not yet available. I actually thought they were a bit more than that, but it was around the beginning of this year that I first looked. Perhaps they dropped the price.
http://www.buymylabradar.com/product.sc?productId=1&categoryId=1

[Tomg]

Let's get Bob one of those!

[Scotchmo]

ES vs SD

ES may be important, but SD (standard deviation) of velocity spread is more telling. SD determines the likelihood of a group size based on the number of shots.

I consider "luck" to be when I shoot better than the statistical odds say I should.

SD will tell me the likelihood (odds) of hitting within a certain accuracy (MOA).

For instance, if a 2 sigma (2x SD) deviation would throw me outside the target, I know that even if everything else is perfect, I will miss about 5% of the shots.

If it only took a 1 sigma error, I would miss about 32% of the shots.

In a 75 shot match, that means about 24 of those shots would not hit the bulls-eye. Those misses were beyond my control. If I did better than that, I would consider myself "lucky". Worse than that, and I was "unlucky" (or I just shot poorly otherwise).

I'm going to shoot a benchrest match tomorrow with my piston gun. I'm using my Diana 54 field target rifle. Based on it's accuracy,  I predict a 600 to 675 score. But I'm hoping for some good luck.