A quick clarification: I don't think anyone belives thier "settings" change.Ballistics are just mathematical equasions. Cold and hard they are.
But enviromental variables are what makes this game all hot and squishy (allong with human factor) . AND fun.
The change is precived target and POA. I'm having fun trying to come up with a formula to explain it in our world of very small projectiles hiting littel metal creatures. Its fun for me.
Realisticly the variance at 100 meters should be neglageable..... maybe not so for high power folks.

A fun mental exercise. Class dissmissed for now.


Please forgive any spelling/grammar issues. Typed on cell phone from moving bus.

The target doesn't move.......... temp plays a very small part............. humidity has no effect..... wind is greatest factor..... light is a factor.... and bar pressure is a very small factor. How do you put math to the effects of light?

Any of you with a ballistics program can change all the above mentioned variables except light and you can see for yourself that the only significant factor is the wind. I don't school is out yet.

What direction are you facing when you shoot?

I shot the Lever Action Silhouette matches in Raton this summer and noticed significant "light forcing". As the sun moved from right to left my point of impact moved too. Early in the morning I was holding center mass on chickens, by the afternoon I was holding on the far left side of the animal to hit them.

I know - open sight vs scope is not a good comparison, but perhaps it is worth considering.

Michael

Y'all make sure you've carefully read jneihouse's post on the subject.

I'm sure the only changes jneihouse makes is for the wind. Center hold all the time.

I'm sure they never make any sight corrections when they switch from match 1 in the morning and match 2 in the afternoon.

Way too many shooters I know make sight corrections during a match. Not just for right/left but up/down. Just saying.

If I see a pattern develop high or low during a match will certainly adjust my sight. Sure of my equipment, It's probably the way I am holding the gun more than anything else. Day warming up morning to noon makes a small difference too. I don't make much change and watch it to confirm its correct.

One things sure shooting multiple misses high or low won't produce good scores.

Boats

Posted this awhile back but here it is again. What you are seeing in the picture is Tureau's experiment. He setup a scope on a tripod and centered the dot at 7am then came back at roughly one hour increments and viewed where the dot was appearing on the target and marked the locations. This was just from the optics and doesn't take into account temperature variations. You can see the mirage increase as the sun goes overhead and then retreats back later in the day to the center again.


Dee

Very interesting, Dee.

Do you know what the distance was and what size target that represents (full size, 3/5, 1/5, other)? Alternatively, is there a write-up somewhere with all the details so you don't have to type it out again? I'd love to read that if it exists.

Thanks.

All I am sure about is that is was 1/5th scale at 100m, typical smallbore Ram setup. There was no write up so to say its a picture does all the talking type deal

To summarize according to Tureau "You gotta work them knobs, hoss" was the write up

Dee

Dee wrote:All I am sure about is that is was 1/5th scale at 100m, typical smallbore Ram setup.

Gotcha.

Guessing by the size of a 1/5 scale ram the total variance (top to bottom) was around 2" (give or take)? That's still a considerable shift in POA to POI.

Someone needs to set up a scope with a time-lapse camera to get the movement on film.

acorneau wrote:Alternatively, is there a write-up somewhere with all the details so you don't have to type it out again? I'd love to read that if it exists.

If you want to read that you're going to have to wait on me to finish and publish my book, "The View At 60X - Tureauisms, Truths and Tureaulosophy of Jerry Tureau." You'll be able to find it in bookstores everywhere.

It'll be Tureautorial Number 16 - "Condition Changes Due to Light." It's between Tureautorial Number 15 - "Condition Changes Due to Wind" and Tureautorial Number 17 - "Spin Drift."

Note that all of these Tureautorials are contained in Chapter 3 - "The Tureaulosophy of Conditions -or- It's Mother Nature, Hoss; She's the Boss." This is NOT to be confused with Chapter 13 - "The Tureaulosophy of Rifle Hold -or- My Trigger Finger is a Nub and That Means I Have to Put a Death Grip on My Rifle."


Dustin

So you show up for sight in, spot on the line is first come first served, edge in and confirm your zeros. Get your starting animal assignment and come to the line first relay. Starting position may be yards left or right from sight in ground is different may be sloped or level, light is probably different. May have shot the sight in a bit cross fire. Wind could have changed, sun is heating things up.

Start your string and strikes develop top half of the critter. Hit them all but high, you are not going to take a couple clicks off the sight ? Keep shooting high and risk one slipping over the back ?

Not me, I paid for that elevation knob am going to use it. Sparingly yes but come down a few.

Boats

Inspired me.
Running a version of above experiment right now. (While Im canning tomatoes)
NRA legal chicken at 25 yards.
full sun. Temps so far started 74f to 85f
scope on tripod in shade
taking occasional photos... Ill post em or mabye make a video tommorrow.
...interesting results, stay tunned.

Guessing by the size of a 1/5 scale ram the total variance (top to bottom) was around 2" (give or take)? That's still a considerable shift in POA to POI.

Someone needs to set up a scope with a time-lapse camera to get the movement on film.
Allen Corneau

That is what he did Allen. Rather than a camera he used a pencil to record what he saw. You would need a X hair in the camera lens to see the movement. He used his rifle and scope that was firmly held in place.

I came up with about the same numbers at 100 m, 500 m, and 1,000 yd. As long as you read the results in minutes and not inches you are OK. It all depends on where the sun is when you set up. The target image follows the sun...... many people say it is the mirage. They are correct because mirage is caused by bending the light rays. You see 2 different things when you read the mirage. You can tell the wind direction by reading the squiggly lines and you also see the target where it isn't. There is so little published on this that it is almost criminal.

Once again. You need a good spotter to tell you where your first shot went and start crankin on them knobs. That is what they are there for. Good shootin to yaall.

We met Jerry Tureau 14 years ago at our first smallbore rifle match in Woolmarket, Mississippi. My son was 9 years old and was shooting a rifle, scope and magazines that cost less than $100 total. That day Jerry started filling our heads with more information than we could absorb and that information has not stopped. Those conversations about wind, mirage, light, projectiles, discipline, dedication to a goal, honesty, integrity and equipment sparked an interest in my son that contributed greatly to his becoming an Aerospace engineer who still loves to shoot silhouette. I carry a copy of that ram plot Jerry created in my Smallbore rifle case. If you recreate Jerry's 1/5 scale experiment be sure you are facing North or slightly Northeast like most of the ranges we shoot on to achieve the same results.