Thread: 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.

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.

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.

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

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

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!)