zeroing your scope

[wrad]

Thanks yobuck. I don't hunt, any more. I'm just fascinated with the physics of very long range precision shooting. My range on my farm is now 1,000 yds, with concrete monuments placed in the ground at 50 yd surveyed intervals. I plan to extend my range to 1 mile this year, and work my way back a station at a time until I can actually hit something at a mile, while still in this lifetime. I'm 67, so I can't dawdle. I still have very good eyesight and a steady hand, so holding submoa is no problem as yet. I am setting up a remote TV spotter at my target frame that will send to a laptop on my portable shooting bench.

 

[4xforfun]

No, my gun won't have a 9' barrel. Look at it this way. If I put the chamber of my rifle over the 100 yd marker (accurately measured to 0.1" with survey instruments), and the real range is supposed to be from muzzle to target, then my muzzle (on a 34" barrel + brake) is about 3' too far forward, and I am really zeroeing at only 97'.

Let me get this strait....you are sighting at 97' (feet) or 97 yards. You said feet!!!! Your BBl is 34" (inches), which is about 3 feet (1 yard) If you set your chamber at exactly 100.00 yards, your muzzle will be 99 yards + - a couple of inches. Now, if your BBl is 9 feet (3 yards) long, your muzzle will be at 97 Yards. You are confusing and mixing yards and feet. Like I said.....the impact difference on + or - 3 yards (9 feet) is .01" (inch) at 100 YARDS (not feet).
And trust me.......NO ONE is as anal as me!!!

 

[bb204]

Seems to me you would want to measure from the muzzle. Are atmospheric conditions having an effect before the bullet leaves the barrel ? Maybe I'm missing something.

 

[jwp475]

Thanks yobuck. I don't hunt, any more. I'm just fascinated with the physics of very long range precision shooting. My range on my farm is now 1,000 yds, with concrete monuments placed in the ground at 50 yd surveyed intervals. I plan to extend my range to 1 mile this year, and work my way back a station at a time until I can actually hit something at a mile, while still in this lifetime. I'm 67, so I can't dawdle. I still have very good eyesight and a steady hand, so holding submoa is no problem as yet. I am setting up a remote TV spotter at my target frame that will send to a laptop on my portable shooting bench.

The difference in 99, 100, 101 yards when zeroing your scope is ZERO. It is undetectable and meaningless

 

[wrad]

Oops! Something was telling me that I had asked a dumb question. I did, in fact, mix yds with ft, so my distances were exaggerated. Very embarassing mistake for an engineer. But my original question was where to place the gun on the 100 yd mark for zeroing. One helpful respondent came back with a vote for putting the muzzle of the gun on that mark, since the muzzle is where the external ballistics start. That would be my vote also. But I have seen many good shooters set up to zero with the gun at different spots - one guy even put his seat on the mark, with everything else out in front of that. One thing I was wanting to avoid was to show up at a match with a bunch of you pros, with my fancy new gun and all the right patches on my hat & jacket & stuff, and set up to zero my gun at the wrong spot with God and everyone else watching. I can't stand giggles. I guess I blew that with my yd/ft error. Thanks for your help everyone.

 

[jwp475]

Oops! Something was telling me that I had asked a dumb question. I did, in fact, mix yds with ft, so my distances were exaggerated. Very embarassing mistake for an engineer. But my original question was where to place the gun on the 100 yd mark for zeroing. One helpful respondent came back with a vote for putting the muzzle of the gun on that mark, since the muzzle is where the external ballistics start. That would be my vote also. But I have seen many good shooters set up to zero with the gun at different spots - one guy even put his seat on the mark, with everything else out in front of that. One thing I was wanting to avoid was to show up at a match with a bunch of you pros, with my fancy new gun and all the right patches on my hat & jacket & stuff, and set up to zero my gun at the wrong spot with God and everyone else watching. I can't stand giggles. I guess I blew that with my yd/ft error. Thanks for your help everyone.

It makes ZERO difference. The difference is un-measureable at 100 yards. MEANINGLESS

 

[wrad]

I know it's meaningless at 100 yds. But if you followed this string back far enough, you would see that my original question was, if you are off several feet on the 100 yd zero, what effect does that have when you drop back to 1 mile? I have received many answers, and run some profiles myself. It does make some minimal difference.

 

[jwp475]

I know it's meaningless at 100 yds. But if you followed this string back far enough, you would see that my original question was, if you are off several feet on the 100 yd zero, what effect does that have when you drop back to 1 mile? I have received many answers, and run some profiles myself. It does make some minimal difference.

I know that is what you asked and I am telling you that it is meaningless. You will not see a difference on a target at 99, 100 or 101 yards so you could not tell the difference. That is why we move out to 300 yards and then to 600 yards and then to 1000 yardds and so on.

The difference in were the bullet hits at 99, 100 or 101 is not going to be enough difference to measure. MEANINGLESS

 

[4xforfun]

I know it's meaningless at 100 yds. But if you followed this string back far enough, you would see that my original question was, if you are off several feet on the 100 yd zero, what effect does that have when you drop back to 1 mile? I have received many answers, and run some profiles myself. It does make some minimal difference.

It's just math. If you are off by 3 YARDS in your distance at 100 when you zero, you will be + or - .01 inch. Or, .01 MOA. That equals .1 inch at 1000 yards, and 1 full inch at 10,000 (ten thousand) yards. 1 inch...... LIKE I SAID, JUST HOW GOOD ARE YOU!!!

Do you see where I am going with this!!!

Like JWP475 said...."MEANINGLESS".

 

[MontanaRifleman]

wrad,

JWP is right. You can use a ballistics program to demonsrate it. If you use this program...

External Ballistics Calculator

Adjust the
Zero Range to 100 yds
Range Interval to 1 yd
Max range to 110 yds
Leave everything else as defaulted, then calculate.

When the calc is complete you will see that the trajectory is completely flat (+ or - less than .05") from 65 yds to 106 yds In another words, the zero doesn't change for 41 yds.

Now try another calc. Open the calc and adjust the
Zero Range to 100 yds
Max range to 1500 yds
Leave everything else as defaulted, then calculate.

Open another calc and adjust the
Zero Range to 101 yds
Max range to 1500 yds
Leave everything else as defaulted, then calculate. Then compare the results down range. At 1000 yds the trajectory is exactly the same. At 1500 yds the difference in trajectory is 0.1" If you make the difference in Zero Range 2 yds, the trajectory changes only 0.2" at 1500 yds. It doesn't matter where you put your muzzle.

What matters a whole lot more is how you interpret your group for zero and what your bullets are doing at 100 yds, as in are they going through yaw and pitch oscillations. This is what is going to affect your down range zero accuracy along with a lot of other things such as what is your real MV? Is your chrony giving you accurate info? What is the real BC of your bullet? These are the things that will affect your down range POI even if everything else is perfect, which it wont be.

Good shooting,

-Mark

 

[wrad]

Hi Mark,

My original stupid question sure seems to have generated a lot of conversation, most of it quite helpful, like yours. I REALLY appreciate your advice on gauging pitch and yaw at 100 yds.

I just got a new chronograph, a PVM-21. Expensive, but accurate to 0.1 fps, and usable under all lighting conditions - even nighttime. Initial testing with it looks excellent.

Several responders, noticing my fixation on getting accuracy down to a gnat's afterbodypart, have asked me just how good a shot I am. I respectfully choose to keep that a secret. Since I have a private range on the farm, the secret will die with me.

Thanks everyone. This was fun.

Walt Davis
Lebanon, OH

 

[4xforfun]

Several responders, noticing my fixation on getting accuracy down to a gnat's afterbodypart, have asked me just how good a shot I am. I respectfully choose to keep that a secret. Since I have a private range on the farm, the secret will die with me.

Thanks everyone. This was fun.

Walt Davis
Lebanon, OH

You don't know what you are missing. I, too, have my own 1200 yard range. I shot alone for most of my life, other than working on poeples' guns. I went to one 1000 yard match. THAT WAS IT. WAY HUGE BIG FUN!!! And with a bunch of like minded people. No one askes if you crazy because you want to shrink that .25 inch group tp .2!!! You never here "why?....whats the use?....you never need that kind of accuracy". Or " a pie plate at 200 is all you need".

You ,sir, are "like minded people". You should try a 600-1000 yard match, a tactical match, an F class match....or something.....YOU DON'T KNOW WHAT YOU ARE MISSING!!!!

GOOD LUCK, SIR!!!

 

[jwp475]

You don't know what you are missing. I, too, have my own 1200 yard range. I shot alone for most of my life, other than working on poeples' guns. I went to one 1000 yard match. THAT WAS IT. WAY HUGE BIG FUN!!! And with a bunch of like minded people. No one askes if you crazy because you want to shrink that .25 inch group tp .2!!! You never here "why?....whats the use?....you never need that kind of accuracy". Or " a pie plate at 200 is all you need".

You ,sir, are "like minded people". You should try a 600-1000 yard match, a tactical match, an F class match....or something.....YOU DON'T KNOW WHAT YOU ARE MISSING!!!!

GOOD LUCK, SIR!!!

Now getting that group smaller, now that is a meaningfull endeaver. Like Montanrifleman pointed out .2" of an inch is much smaller than your scope will adjust at 1500 yards and that is less that the reticlewill cover


This is exactly what these forums are for to help us avoid meaningless persuits

 

[4xforfun]

Now getting that group smaller, now that is a meaningfull endeaver. Like Montanrifleman pointed out .2" of an inch is much smaller than your scope will adjust at 1500 yards and that is less that the reticlewill cover


This is exactly what these forums are for to help us avoid meaningless persuits

When speeking of .25 vs .2, I was talking 100 yard groups. If I ever get to that .25 inch range at 1500, well, you may just call me G O D!!!