Need help to "true" my chart...or should I bother?

[hereinaz]

Verify every tool is accurate and measuring tools are calibrated. And it will become apparent where the issue lies. It isn't the app.

Verify zero with 10 shots.
Verify all the inputs to the app.
Verify your scope.
Verify distances to the targets.
Verify temp and environmental factors.

At least one thing is off, and that's why you can't true the app to the results any closer. You have some suggestions. Start at the beginning, it will be an important experience, and you will find it. Keep asking questions, too.

I would bet your scope or data input is off some amount.

 

[JLane330]

Lots of good info in this thread. I personally believe a 100yd zero is too close and shouldn't be relied upon. All my rifles are zero'd at 200 yds, but what I do is use the longer groups (300-400 yds) to set my zero. Because this is a hunting rifle, who cares if you're off by a 1/2" (or choose a small #) at 200 yds? If you are on at longer distances, use that and work backwards, then verify that your 200 yd zero (no reason to set it at 100 out here) is close enough for hunting. I've found it more accurate that way.
As someone else mentioned, don't be afraid to play with the BC of the bullet (along with velocity) a little to dial in the chart to hit your 300 and 600yd performance. A little tweak can fix the curve.
Disclosure, I'm not a long range shooter per se, but do it for fun when practicing for a hunt. The above has worked very well for me and killed plenty of animals. Another method I've seen used for hunting is using maximum point blank range. It depends on what game you're hunting, but I've seen it work great for elk/deer.

 

[wind gypsy]

Lots of good info in this thread. I personally believe a 100yd zero is too close and shouldn't be relied upon. All my rifles are zero'd at 200 yds, but what I do is use the longer groups (300-400 yds) to set my zero. Because this is a hunting rifle, who cares if you're off by a 1/2" (or choose a small #) at 200 yds? If you are on at longer distances, use that and work backwards, then verify that your 200 yd zero (no reason to set it at 100 out here) is close enough for hunting. I've found it more accurate that way.

Using longer range groups to set a shorter zero only adds potential error in your zero, not the other way around.

There is a reason basically everyone who understands ballistics and and shoots competitively zeros centerfire rifles at 100 yards.

 

[JLane330]

What load are you shooting, barrel length? The actual numbers you’re getting seem very unlikely which is probably why you can’t get the app to line up. I’d guess one of the following is at play:
1. Poor zero at 100
2. Scope doesn’t track accurately
3. Crazy down drafts after the first couple hundred yards?

Using longer range groups to set a shorter zero only adds potential error in your zero, not the other way around.

There is a reason basically everyone who understands ballistics and and shoots competitively zeros centerfire rifles at 100 yards.

Maybe I did a poor job at explaining it, but I guess I was agreeing with you on #1. Thing is, a 100 yd zero can look great, but you can still have further distances that don't match the curve. For the ranges being discussed here, it comes down to a few basic things...time of flight (affected by MV, BC and environment) and leverage (distance) mostly. Given a load with X velocity, and a given bullet BC, the only variable you can change is distance, which is what I'm suggesting. Errors that don't show at 100 yds will start to show up on the target at further distances. The other variable is the shooter, so I'm assuming a competent rifleman.

Now, for hunting (which was the discussion I believe), a 200 yd zero on a 270 may make more sense anyways. I only shoot at 100 yds to confirm I'm on paper, otherwise it's too close and doesn't tell me much. A group at 300 is a better indicator of what's going on and how accurate the rifle is imo. I fine tune my zero as I move out, then come back to 200 to confirm. Trial and error, yes. Accurate, every animal I've ever shot at would agree.

Let me ask a simple question: Would the average hunter/shooter be able to tell the difference of 1/4 or 1/2 MOA change on a scope at 100 yds when they are getting a 1/2 to 1in group?

 

[MidGAHunter]

Now, for hunting (which was the discussion I believe), a 200 yd zero on a 270 may make more sense anyways.

Why MPBR isn’t as good of an idea as it seems...

Zeroing for maximum point blank range is quite often offered as a good way to zero to eliminate “thinking” when an animal steps out. Seems simple enough- zero a rifle at a range that the bullet doesn’t rise above a predetermined height, and when it falls below line of sight at that same distanc...

www.rokslide.com

Page 2 of the above thread has some good information from Form as to why a 100 yard zero is optimal.

 

[wind gypsy]

Maybe I did a poor job at explaining it, but I guess I was agreeing with you on #1. Thing is, a 100 yd zero can look great, but you can still have further distances that don't match the curve. For the ranges being discussed here, it comes down to a few basic things...time of flight (affected by MV, BC and environment) and leverage (distance) mostly. Given a load with X velocity, and a given bullet BC, the only variable you can change is distance, which is what I'm suggesting. Errors that don't show at 100 yds will start to show up on the target at further distances. The other variable is the shooter, so I'm assuming a competent rifleman.

Now, for hunting (which was the discussion I believe), a 200 yd zero on a 270 may make more sense anyways. I only shoot at 100 yds to confirm I'm on paper, otherwise it's too close and doesn't tell me much. A group at 300 is a better indicator of what's going on and how accurate the rifle is imo. I fine tune my zero as I move out, then come back to 200 to confirm. Trial and error, yes. Accurate, every animal I've ever shot at would agree.

Let me ask a simple question: Would the average hunter/shooter be able to tell the difference of 1/4 or 1/2 MOA change on a scope at 100 yds when they are getting a 1/2 to 1in group?

The linked thread above covers most of this but i'll respond. Yes, precision can fall apart at distance on a load that looks good at 100, but using longer distances to zero is still a bad idea. Ammo doesn't magically shift left, right, up, or down from the trajectory it was on at 100 yards but wind, air density, mirage, etc do impact your POI at further distances increasingly more the further out you go. So if you "fine tune" your zero based on longer distances you are actually just inducing errors in your zero based upon the conditions for that one shot scenario with the atmospheric conditions for that one point in time. 1/2" at 100 might not mean much, what about when you have conditions completely the opposite of what led you to "fine tune" your zero off 1/2"? Now your zero is off 1 MOA, and a 1 MOA miss at 600 isn't negligible.

Zeroing at 100 and then hunting with elevation of your scope adjusted to reach whatever you want (200 yds, MPBR, etc) does make sense. Actually zeroing based on where your bullets hit a target at 200, 300, etc yards at one point in time is likely just inducing error in your system.

 

[bdg848]

I went to the range and, yes, my zero was a little low. With that fixed, my data is lining up a lot closer now. I think I used a target that was too large and added to much room for saying that the group is "centered" when in reality it is slightly low. This time I used the smallest center dot target that I could see through the scope. Thank you all for the help.

 

[Rock-o]

Search the internet for "weaponized math x-factor try dope". You'll find links to a couple-several different articles. I think this is the best one - maybe not. Anyway, it's really easy, no chronograph and no ballistic calculator needed - just shoot.

https://www.snipershide.com/precision-rifle/truing-your-ballistic-calculator-with-weaponized-math/

After collecting your data, if you really want to know your muzzle velocity, than go to http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi and enter all the data you can. Don't skimp, for example, measure the center of your scope to the center of your bore. Enter correct environmental, correct bullet data. Guess at a speed and see what it spits out. A little bit of trial and error guessing speed and you'll find the one that gives you the data that matches your real life shooting.

 

[Rob5589]

Maybe I did a poor job at explaining it, but I guess I was agreeing with you on #1. Thing is, a 100 yd zero can look great, but you can still have further distances that don't match the curve. For the ranges being discussed here, it comes down to a few basic things...time of flight (affected by MV, BC and environment) and leverage (distance) mostly. Given a load with X velocity, and a given bullet BC, the only variable you can change is distance, which is what I'm suggesting. Errors that don't show at 100 yds will start to show up on the target at further distances. The other variable is the shooter, so I'm assuming a competent rifleman.

Now, for hunting (which was the discussion I believe), a 200 yd zero on a 270 may make more sense anyways. I only shoot at 100 yds to confirm I'm on paper, otherwise it's too close and doesn't tell me much. A group at 300 is a better indicator of what's going on and how accurate the rifle is imo. I fine tune my zero as I move out, then come back to 200 to confirm. Trial and error, yes. Accurate, every animal I've ever shot at would agree.

Let me ask a simple question: Would the average hunter/shooter be able to tell the difference of 1/4 or 1/2 MOA change on a scope at 100 yds when they are getting a 1/2 to 1in group?

I see what you're trying to say, just a bit confusing. Zero at 100 but, always confirm further out. Your "zero" isn't the same as what the load does beyond that.

 

[Reburn]

Maybe I did a poor job at explaining it, but I guess I was agreeing with you on #1. Thing is, a 100 yd zero can look great, but you can still have further distances that don't match the curve. For the ranges being discussed here, it comes down to a few basic things...time of flight (affected by MV, BC and environment) and leverage (distance) mostly. Given a load with X velocity, and a given bullet BC, the only variable you can change is distance, which is what I'm suggesting. Errors that don't show at 100 yds will start to show up on the target at further distances. The other variable is the shooter, so I'm assuming a competent rifleman.

Now, for hunting (which was the discussion I believe), a 200 yd zero on a 270 may make more sense anyways. I only shoot at 100 yds to confirm I'm on paper, otherwise it's too close and doesn't tell me much. A group at 300 is a better indicator of what's going on and how accurate the rifle is imo. I fine tune my zero as I move out, then come back to 200 to confirm. Trial and error, yes. Accurate, every animal I've ever shot at would agree.

Let me ask a simple question: Would the average hunter/shooter be able to tell the difference of 1/4 or 1/2 MOA change on a scope at 100 yds when they are getting a 1/2 to 1in group?

Here is a good thread where we beat on 100 yard zero and why,

At what yardage do you dial?

Will shortly have my first “dial” scope. In a hunting situation at what point do you dial? At 300 yards when it is a short hold over? This is based on elk. Appreciate any insights and experience.

www.rokslide.com

 

[Rifles And More]

Improper zero and three shot groups are the start of most problems.

10 shots @ 100 and center the group for zero. You will find out that most rifles aren’t the tack drivers advertised. That’s ok.

The programs are great, but be sure to accurately input ALL the info.

Best way to know your drops = shoot your drops. Out to 600 shouldn’t be too bad.