DOPE help

[kornface13]

I've been playing with multiple calculators all night and I cannot get my data to match up.

I have solid data for 100, 300, and 600 yards.

I zero at 300 (5100 feet elevation)
+4 MOA = 100 yards (5900 feet elevation - not sure how much impact this 800 feet of difference would make on my calculations)
-11.75MOA = 600 yards (5100 feet elevation)

I've taken velocity measurements three different times and the average for 5 or 10 rounds is always right around 2630-2640. I'm using 2635 as my velocity. 5100 feet altitude. 168gr Z-Max (same as A-Max) - G1 BC 0.475.

When I plug the numbers into the calcs, they say I should be at +4.7MOA for 100 yards, but +4 puts me dead on the bullseye on paper. THey also say -10.6MOA for 600 yards, but I had to dial -11.75MOA to be center-ish on the steel plate

These numbers seem entirely too far off. Is this normal?

 

[Diver160651]

I've been playing with multiple calculators all night and I cannot get my data to match up.

I have solid data for 100, 300, and 600 yards.

I zero at 300 (5100 feet elevation)
+4 MOA = 100 yards (5900 feet elevation - not sure how much impact this 800 feet of difference would make on my calculations)
-11.75MOA = 600 yards (5100 feet elevation)

I've taken velocity measurements three different times and the average for 5 or 10 rounds is always right around 2630-2640. I'm using 2635 as my velocity. 5100 feet altitude. 168gr Z-Max (same as A-Max) - G1 BC 0.475.

When I plug the numbers into the calcs, they say I should be at +4.7MOA for 100 yards, but +4 puts me dead on the bullseye on paper. THey also say -10.6MOA for 600 yards, but I had to dial -11.75MOA to be center-ish on the steel plate

These numbers seem entirely too far off. Is this normal?

Why are you not using a 100 yard zero?

The way you are doing it your zero will float.. it is one of the issues with a long range zero as well as hold unders & overs instead of all hold overs

 

[kornface13]

Why are you not using a 100 yard zero?

The way you are doing it your zero will float.. it is one of the issues with a long range zero as well as hold unders & overs instead of all hold overs

I used to primarily shoot the gun at 300 yards. I'm starting to get into PRS so here I go trying to use a calculator for all the other distances. I didn't realize my 300 yard zero would cause issues. I knew that I'd have to hold under on shots closer than 300, but I figured that was fine as long as I had the DOPE. Also it seemed better as I don't have a 20MOA rail and I need to be able to get out to 1200 yards.

Why will my zero float? And what does that mean?

 

[Diver160651]

I used to primarily shoot the gun at 300 yards. I'm starting to get into PRS so here I go trying to use a calculator for all the other distances. I didn't realize my 300 yard zero would cause issues. I knew that I'd have to hold under on shots closer than 300, but I figured that was fine as long as I had the DOPE. Also it seemed better as I don't have a 20MOA rail and I need to be able to get out to 1200 yards.

Why will my zero float? And what does that mean?

The 100 yard zero is almost completely impervious to the altitude that you’ll find any of the PRS matches. Long range zeros are not. That said in most calculators you can add zero conditions-

Either way, it completely complicates everything and does nothing for your ability to dial longer ranges.

 

[kornface13]

Alrighty. Well thats good enough for me. Switching to 100 yard zero right now.... No reason to make this shit any harder on myself.

Thank you!

 

[Diver160651]

Alrighty. Well thats good enough for me. Switching to 100 yard zero right now.... No reason to make this shit any harder on myself.

Thank you!

No worries, it will be easier to get a great zero at 100 too. With your attitude you’ll find a lot of really experienced people willing to help, many including shooting with you.

 

[ShtrRdy]

When you shot at 100 yd. and 600 yd, was the air temperature different that when you zeroed at 300 yd?

A 100 yd zero is much more forgiving since the bullet is reaching its apex for this shot. What this means is the bullet is at the zero elevation for a few yds before and after it passes the 100 yd distance.

Is your bullet a 30 cal?

 

[Diver160651]

When you shot at 100 yd. and 600 yd, was the air temperature different that when you zeroed at 300 yd?

A 100 yd zero is much more forgiving since the bullet is reaching its apex for this shot. What this means is the bullet is at the zero elevation for a few yds before and after it passes the 100 yd distance.

Is your bullet a 30 cal?

That’s happening, sure but it also happens at other distances.

The bullet is falling immediately after leaving the barrel. Whenever we spin the turrets we are zeroing at that new range and creating the same basic concept.

The sole reason the 100 yard zero works so well for PR, is that the SOB angle needed at 100 is not too steep like a 25 or 50 yard zero that creates drastic hold unders, yet still close enough overcome most environmental conditions.

 

[AIAW]

 

[Diver160651]

View attachment 7020982

^ the illustration show the issue with the 50 yard zero as well.

 

[kornface13]

When you shot at 100 yd. and 600 yd, was the air temperature different that when you zeroed at 300 yd?

A 100 yd zero is much more forgiving since the bullet is reaching its apex for this shot. What this means is the bullet is at the zero elevation for a few yds before and after it passes the 100 yd distance.

Is your bullet a 30 cal?

Shot 300 and 600 on the same day. Maybe 10 degrees colder the day I shot 100 yards.

Yes, bullet is 30 cal

 

[kornface13]

Scope is zero’d at 100 now. We’ll see how the match goes tomorrow.

I’m still not really trusting the data though. I had to move +4MOA to go from 300 to 100. I can’t listen to the calculator and go -4.6 MOA to get back to 300. That’s too much.

I’m going to be 10 feet off at 1k yards :|

Maybe my chrono is a piece of shit. If someone has a lab radar tomorrow I’ll see if I can trade beer for a velocity check.

 

[Diver160651]

Scope is zero’d at 100 now. We’ll see how the match goes tomorrow.

I’m still not really trusting the data though. I had to move +4MOA to go from 300 to 100. I can’t listen to the calculator and go -4.6 MOA to get back to 300. That’s too much.

I’m going to be 10 feet off at 1k yards :|

Maybe my chrono is a piece of shit. If someone has a lab radar tomorrow I’ll see if I can trade beer for a velocity check.

How small is your physical groups at 100? How certain ate you that you are absolutely zeroed?

For what it is worth, a tiny 1/8" offset from a dead centered zero = .12MOA, or .52" offset, a .5 moa issue at 300 or 1000. So you MUST account for your zero offset in the calculator if you have one.. most of us do.

1.3mils or abut 4.5MOA, is relatively normal for 300yards with a 308 in your velocity range with a bit lower station number (inHg). If your running 1/4minute scope don't get to caught up in the numbers you can not possibly dial for your down range solution.

 

[Deleted member 113831]

Scope is zero’d at 100 now. We’ll see how the match goes tomorrow.

I’m still not really trusting the data though. I had to move +4MOA to go from 300 to 100. I can’t listen to the calculator and go -4.6 MOA to get back to 300. That’s too much.

I’m going to be 10 feet off at 1k yards :|

Maybe my chrono is a piece of shit. If someone has a lab radar tomorrow I’ll see if I can trade beer for a velocity check.

Is your scope height actually 1.5 inches? That is what it says in that drop table.

 

[kornface13]

How small is your physical groups at 100? How certain ate you that you are absolutely zeroed?

For what it is worth, a tiny 1/8" offset from a dead centered zero = .12MOA, or .52" offset, a .5 moa issue at 300 or 1000. So you MUST account for your zero offset in the calculator if you have one.. most of us do.

1.3mils or abut 4.5MOA, is relatively normal for 300yards with a 308 in your velocity range with a bit lower station number (inHg). If your running 1/4minute scope don't get to caught up in the numbers you can not possibly dial for your down range solution.

I'll double check this. Its definitely very close to center. But awesome info. Thanks yet again! ALso I realized that .6 MOA is barely over 1.6 inches. Totally possible that the calc is right and I'm slightly high/low/have a missing offset.

Is your scope height actually 1.5 inches? That is what it says in that drop table.

Yeah its right around 1.5-1.6. Hard to get a perfect measurement though.

 

[surprise]

I had a similar issue a while back, and I ended up being off just enough that it was frustrating. One of the things that helped was making sure that I was doing my job behind the rifle. Don’t forget to really focus on your follow through and make sure you’re holding the rifle consistently every time. It goes without saying that every imperfection in your shooting is amplified at distance, but sometimes we all need to be reminded of these things. I sure did, and I ended up having someone watch me while I was shooting and pointed a few things out and since then my numbers have been much better, by that I mean not far off from what the calculations say.

I hope your match goes well today

 

[kornface13]

Match went well. The app data was pretty close around 600 and closer. Beyond that the wind made it quite difficult to tell what the hell was going on. Appreciate all the help and advice!