Difference between ballistic chart and real word results

I am shooting a 7mm08 17 inch barrel with handloaded162 Eldms. 41.5gr of 2208.

I have chronographed the load and have a speed of 2575fps which I thought was about right. Gun is zeroed at 100y.

I have just got a sew set of swaro rangefinding binoculars which when shooting at 400 yards showed a dial up on 7.5 MOA. Of interest was my strelok app showed the same.

Now when shooting my impact was around 6 inches high. 6.25 brought it back down to bang on. Only thing is for me to get the binos reading that MOA I had to enter a speed of 2750fps which seems a bit too fast.

Thoughts?

I have just got a new pair of range

First thing I'd check is the zero, is the range actually 100Y (we have a range here that everyone takes as 100Y but is actually 89Yand another that has a 100M mound then 200/300/400 Yards etc and are you using the centre of a decent 5 shot group?

Speed looks right, mate shoots 16.5” and same load.
Attachment 240054

If your zero is perfect at what ever zero you choose and your using a litz g7 bc.
Then it is just a matter of validating for speed and if your shooting over 500m you really want to be allowing for atmospherics as will make a difference in elevation.
There are some great videos out there.
I recommend accuracy 1st by Tod and Coby Hodnett.
Pretty much the be all and end all in long range knowledge.


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A zero of 80 or 120 yards changes the 400y adjustment very little.

The trajectory is acting like you've zeroed 2" high at 100y.

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Originally Posted by Makros

A zero of 80 or 120 yards changes the 400y adjustment very little.

The trajectory is acting like you've zeroed 2" high at 100y.

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Which is no problem if you enter the offset into your ballistics app

Got your scope height excatly correct?

whats the scope and does it dial correctly??

Spend time getting yr exact 100yds zero group,two or 3 visits.Then go to 400yrds using 100yds zero and fire 4shots in perfect conditions.Do this twice=2 visits.This will give you your 400yd drop.This will give you yr exact dial up for 400yds.Just make the data for yr apps fit yr practical result.
Nothing bets real world results.

Another variable to consider is does your scope dial in true MOA?

I don't know what I'm doing but I have done similar to Trout by sighting in at 100m then shooting 200 and 300m groups and adjusting Strelok app bullet speed to match the drop I had.

Works ok to give confirmation of bullet path but I only shoot to 300m.

Ye i know where im going to 400yds on a good day,but most deer are under 300yds.But its nice to be accurate.

There’s a hornady podcast that talks about this. I think they address it in the podcast regarding their 4dof app. I never paid too much attention as I don’t have a problem with my actual trajectory vs what strelok tells me. Could be atmospherics. In saying that, have you grouped at that distance? 6 inches could just be the random deviation potential of that load and if you haven’t shot enough rounds to expose the outer edges of the accuracy potential you may be looking at a small sample of the group which randomly may be on the upper edge of the group. Equally, is the bc entered correct? Is the twist rate correct? Scope height accurate? A bunch of small deviation in data entry’s can have a dramatic effect on the down range point of impact. Equally, shooting off a bipod on a hard surface may result in bipod bounce throwing the shots slightly high. Eld-m have a high enough bc that thermal activity shouldn’t effect it at that range, another consideration, are your binos true ballistic range?is the angle set accurately? Shooting at angles changes poi alot

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Originally Posted by Jus

There’s a hornady podcast that talks about this. I think they address it in the podcast regarding their 4dof app. I never paid too much attention as I don’t have a problem with my actual trajectory vs what strelok tells me. Could be atmospherics. In saying that, have you grouped at that distance? 6 inches could just be the random deviation potential of that load and if you haven’t shot enough rounds to expose the outer edges of the accuracy potential you may be looking at a small sample of the group which randomly may be on the upper edge of the group. Equally, is the bc entered correct? Is the twist rate correct? Scope height accurate? A bunch of small deviation in data entry’s can have a dramatic effect on the down range point of impact. Equally, shooting off a bipod on a hard surface may result in bipod bounce throwing the shots slightly high. Eld-m have a high enough bc that thermal activity shouldn’t effect it at that range, another consideration, are your binos true ballistic range?is the angle set accurately? Shooting at angles changes poi alot

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This.

Been doing this exact exercise with the 6mm ARC the last few days. First visit to range I focus on 100 M zero. I always like to be 50 to 65 mm high at this distance. I don't sweat it exactly, but I want two groups that show the same result, 3 shot groups are only OK if the rifle is CONSISTENTLY doing 12 -15mm or better. If it isn't then at least two 5 shot groups are what I want. It also pays to remember that you don't have to be shooting real small groups to set up a 500M rifle, 30 or 40mm at 100M are fine if they are consistent and repeatable. Remember to enter the carefully measured zero offset into the ballistics programme.


I then move back to 400Y (365M) - I think this is about the minimum distance to do this exercise at but it produces reasonable group's and doesnt knock your confidence arround too much. I set up a big bit of paper with two aiming points at the top (so you have about 500-600mm of clear paper below it). Without any dial (or reticle holdover if that's how you shoot) I fire a 5 shot (10 is really better) group. I go forward and carefully measure the actual drop to the group centre (don't worry what the group size is). Does the actual drop match what the ballistics programme is telling you? If not correct it. Then dial or holdover and shoot a second group at the second aiming point. It should be bang on if you scope dials correctly but if it's not then you now have an idea of the "correction" your scope needs.

Then go hunting, your rifle is good for at least 500-600M everything else being equal, which of course it isnt. Position, wind, and other variables require consideration in setting a personal limit, which for me is about 350M (but I'm an old, pot-belly Fudd haha!)

1st of all, is your scope tracking accurately? And is it properly levelled
2nd is your BC right (yes if you are using litz BC with same twist barrel)
3rd, is your velocity correct? If using an optical chrony, id look at this 1st after making sure the scope is right.

Can only be those things, unless you are shooting steep up or downhill

I get 7.89 moa for 400 yards with a 100 yards zero, assuming you have a 9.5 twist i get a stability of 1.45 which is propably OK but they dont reccomend going under 1.5

Personally ive gone to 1.3 and have been all good out to 1000 yards

This was using the applied ballistics app and the listz G7
And just my local atmospherics, but that wont matter heaps between AKL and Hams at 400 yards

Greetings,
The key is everything must be the same. If you shoot in the field prone with a bipod then your 100 yard (200 yards would be better) zero should be prone with a bipod. I have been on rather a steep learning cure recently with F class shooting. For setting up my rifles for 300 and 600 yards they are shot at 200 metres with the predicted impact from my ballistic chart marked on the target. This is based on chronographed velocity and published BC. I assume that you have checked the actual value of your scope clicks. Many scopes vary from what is marked on them. I think a lot of shooters kneecap themselves doing a base zero at 100 metres or worse yards. The other thing that can be out is the rangefinder. Some chronographs can be dodgy but mine is a 35P which measures the velocity twice using a 3 screen set up and my predicted 600 yard velocity is bang on with that measured by the range software. There are a bunch of things that should be checked before entering bullshit velocity in your app. This will just bite you on the arse further out.
One last thing. Are you aiming marks good enough to be able to precisely aim at each range? Many are not.
Regards Grandpamac.

This all goes to show that theory is pretty good, but not infallible. There are far too many variables to take into account (wind, temperature, humidity, altitude, barrel manufacturing tolerances, bore wear, case neck tension, case manufacture tolerances, chamber dimensions, etc.) that make it impossible for theory to be exact, just near enough. The exact results can only be ascertained by actual shooting, bearing in mind that there are even more variables to consider to achieve consistent results. Top-level target shooters only seek to minimise the variables on any given day as they realise that it is impossible to eliminate them.

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Originally Posted by Sikahunter262

I am shooting a 7mm08 17 inch barrel with handloaded162 Eldms. 41.5gr of 2208.

I have chronographed the load and have a speed of 2575fps which I thought was about right. Gun is zeroed at 100y.

I have just got a sew set of swaro rangefinding binoculars which when shooting at 400 yards showed a dial up on 7.5 MOA. Of interest was my strelok app showed the same.

Now when shooting my impact was around 6 inches high. 6.25 brought it back down to bang on. Only thing is for me to get the binos reading that MOA I had to enter a speed of 2750fps which seems a bit too fast.

Thoughts?

I have just got a new pair of range

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Suspect the reticle on the EL Range is not exactly dead centre of where the beam is hitting.

Try getting your binos really stable, rested on something so you are not physically holding them up. A tripod is ideal but can be done with a backpack.

Now, range a very definite target which is only slightly bigger than the reticle, and nake sure its dead centre. Then turn your binos upside-down, and sideways, and repeat.

If you arr getting wildly different readings, keep trying using different areas of the reticle (12 oclock, 3, oclock, 6 and 9) until you get a more consistent reading.

Been seeing this quite a lot with rangefinding binos, even top end ones. Much prefer a dedicated handheld unit as they are much less prone to this issue.

Anyway, very simple ballistic chart.

If you have a rifle shooting a projectile with a 0.5-0.6 G1 BC and a muzzle velocity between 2,600 to 2,800 fps, the following should apply with a scope in Mils.

100 yard zero

200 yards 0.5 Mils

300 yards 1 Mil

400 yards 2 Mils

500 yards 3 Mils

600 yards 4 Mils

You might have to adjust between 0.2 to 0.3 mils (usually add) at 400 yards plus, but usually this is very close.

With your setup, I'd say the call of 7.5 MOA is more likely to be correct for 400 yards vs. 6.25, to make it easier, refer to this quick MOA to Mils chart:

https://docs.google.com/spreadsheets...mFqIo/htmlview

So, to keep it simple, potential list of issues, in order of likelyhood:

1. Your binos are not ranging correctly

2. Your scope is not dialling accurately, is it a Leupold...? :psychotic:

3. Your zero is off

4. Your chrono data is off (unlikely as it sounds about right with your setup).

Scope height only affects maximum point blank range, not the external ballistics of the bullet, and is a subject best left for now.

Quote:

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Originally Posted by caberslash

Suspect the reticle on the EL Range is not exactly dead centre of where the beam is hitting.

Try getting your binos really stable, rested on something so you are not physically holding them up. A tripod is ideal but can be done with a backpack.

Now, range a very definite target which is only slightly bigger than the reticle, and nake sure its dead centre. Then turn your binos upside-down, and sideways, and repeat.

If you arr getting wildly different readings, keep trying using different areas of the reticle (12 oclock, 3, oclock, 6 and 9) until you get a more consistent reading.

Been seeing this quite a lot with rangefinding binos, even top end ones. Much prefer a dedicated handheld unit as they are much less prone to this issue.

Anyway, very simple ballistic chart.

If you have a rifle shooting a projectile with a 0.5-0.6 G1 BC and a muzzle velocity between 2,600 to 2,800 fps, the following should apply with a scope in Mils.

100 yard zero

200 yards 0.5 Mils

300 yards 1 Mil

400 yards 2 Mils

500 yards 3 Mils

600 yards 4 Mils

You might have to adjust between 0.2 to 0.3 mils (usually add) at 400 yards plus, but usually this is very close.

With your setup, I'd say the call of 7.5 MOA is more likely to be correct for 400 yards vs. 6.25, to make it easier, refer to this quick MOA to Mils chart:

https://docs.google.com/spreadsheets...mFqIo/htmlview

So, to keep it simple, potential list of issues, in order of likelyhood:

1. Your binos are not ranging correctly

2. Your scope is not dialling accurately, is it a Leupold...? :psychotic:

3. Your zero is off

4. Your chrono data is off (unlikely as it sounds about right with your setup).

Scope height only affects maximum point blank range, not the external ballistics of the bullet, and is a subject best left for now.

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Greetings,
Some very good points in this post. Thanks @caberslash. Checking the accuracy of the readings from a rangefinder may not be as tricky as it sounds. Our local Council plus many others has a GIS system for land information which is available on their web site website. This includes Cadastral info, property boundary measurements and such plus aerial photos with decent detail. Ours also has a distance tool that allows you to measure the distance between two points with a couple of mouse clicks. I use it quite a bit so have a look on your local Council web site to see what is on offer. I checked the length of one of our boundaries which is a little under 400 metres with the distance tool and found the latter to be quite accurate. You may also be able to use the GPS coordinates on the GPS app on your bat phone to check the distance but this may need some Geometry to calculate. Have not tried this one yet.
Regards GPM.

I had the same problem with a swarovski z3 once. I'm guessing the clicks weren't calibrated to exactly moa

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Originally Posted by Gkp

I had the same problem with a swarovski z3 once. I'm guessing the clicks weren't calibrated to exactly moa

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From people in the know it used to be only Nightforce that had perfectly calibrated adjustments and from what I have seen from other high-end optics I tend to agree.


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