Calling all ballistics experts

Hi Team so iv had a 7mm RM for a year or so & I haven't had much luck dialling it if I use the shooter app its telling me with a 200y zero , at 400y it is -16 low at 500y -31.9 low so that = 3.8moa & 6.1 to bring it up to zero ..yet iv just done a bit of a drop chart today & its pretty much half of what the app is telling me so the actual drop is 8 inches low at 400 , & at 500 its 15.5 " iv checked all the info that I have put into the app it all seems correct :
bullet diameter 0.284
weight 162 eld-x
vel 3130.00
bc 0.6300
zero at 200y

I use the same app for the 308 it works really well so its got me stumped ! not sure if it makes a diff but the barrel is 26" long...thoughts ?

This is what shooter gave me with your data

400y drop 16.0" or 3.8moa
500y drop 31.9" or 6.1moa

What is the scope you are using?

Not saying shooter is the best app but it works with 4 calibers I use it for very well as long as the info is correct.

Half the required dope at those ranges is not load or atmospherics.

Flattest shooting 7mm mag in history [emoji16]



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you havnt got it set to 1/2 moa clicks in for the chart?

Yep your data does seem right, but then real world results are telling you different. You'll just have to use the true data ( from your drop chart ) to dial hits.
But I would replicate the results again and try dialing with those data.

ie; reconfirm what you got from your fired drop chart.

What are the atmospherics? are you sure your 200y yard zero is bang on and conditions for zero are entered? is the scope adjusting correctly? is your speed accurate/how was it measured?

If its out it can be adjusted/trued back but it shouldnt be 50% out!

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Originally Posted by 199p

This is what shooter gave me with your data

400y drop 16.0" or 3.8moa
500y drop 31.9" or 6.1moa

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Yep that what mine is telling me as well but using it shoots high.

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Originally Posted by veitnamcam

What are the atmospherics? are you sure your 200y yard zero is bang on and conditions for zero are entered? is the scope adjusting correctly? is your speed accurate/how was it measured?

If its out it can be adjusted/trued back but it shouldnt be 50% out!

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My freinds vx3 is marked 1/4moa but adjusts 1/2 moa which led to some WTFs sighting in, second hand so maybe some swapping of turrets went on or I dunno.

I know nothing...but...have you validated your fps with an alternative chrono?

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Originally Posted by R93

What is the scope you are using?

Not saying shooter is the best app but it works with 4 calibers I use it for very well as long as the info is correct.

Half the required dope at those ranges is not load or atmospherics.

Flattest shooting 7mm mag in history [emoji16]



Sent from my SM-G965F using Tapatalk

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Go the browning hells cannon ! iv got a meopta 6-18x50 initially I thought perhaps the scope wasn't dialling correctly theres a chance its not , however by just doing the drop chart today at those two ranges vs the app im thinking something else is up...could be a browning 7Rm for sale starting price 7k...possibly a trade for a blazer in the same cal :)

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Originally Posted by Boaraxa

Go the browning hells cannon ! iv got a meopta 6-18x50 initially I thought perhaps the scope wasn't dialling correctly theres a chance its not , however by just doing the drop chart today at those two ranges vs the app im thinking something else is up...could be a browning 7Rm for sale starting price 7k...possibly a trade for a blazer in the same cal :)

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Won't be the rifle or ammo. It will be a scope or data issue.

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Originally Posted by Tahr

I know nothing...but...have you validated your fps with an alternative chrono?

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Hi Tahr , not as such though my mate spent some time coming up with the load for me tested quite a few loads so I would be supprised if it was that far out but defiantly something for consideration .

I just checked the info VC & its set on 1/4 so that looks correct .

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Originally Posted by Boaraxa

Hi Tahr , not as such though my mate spent some time coming up with the load for me tested quite a few loads so I would be supprised if it was that far out but defiantly something for consideration .

I just checked the info VC & its set on 1/4 so that looks correct .

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Set up rifle on target @100y and a target with say a line 5 inches up and 10 inches up(10.47 inches if being pedantic) and adjust up 5moa and 10 moa and see if xhairs are lining up on the lines above.

+1 calibrate your scope for dial up. That’s a huge discrepancy.
Also suggest the muzzle velocity and bc quoted are a tad optimistic .
Don’t know about the bc for ELDx but Hornady overstated the old 162 AMAX by quite a bit.

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Originally Posted by Boaraxa

Hi Tahr , not as such though my mate spent some time coming up with the load for me tested quite a few loads so I would be supprised if it was that far out but defiantly something for consideration .

I just checked the info VC & its set on 1/4 so that looks correct .

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I asked because I'm fiddling with an XBolt in 270wsm at the moment and it has a very tight and short chamber. So I loaded to ADI max and saami length and the velocity was 140 fps more than I predicted and what quick load predicted. I'm now 10 thou under saami length which is just touching the lands and 3 grns off max and the velocity is still a little bit over the book max load.

I've got Zeiss HD5 dial with dial turrets that you can try for a comparison.

For $410 you can try out comrade mao's scope. Its on the forum somewhere.

I checked using JBM. Very similar outputs to @199p actually.
The simplest explanation for the discrepancy is that you have zeroed at 300 yards rather than having your poi dead on at 200. Other than that, the other simple explanation is as others have suggested; that your dials are actually moving 1/2 moa per click instead of 1/4 moa; or, that the dial markings themselves are not labelled correctly for the scope. Good luck.:)

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Originally Posted by Woody

I checked using JBM. Very similar outputs to @199p actually.
The simplest explanation for the discrepancy is that you have zeroed at 300 yards rather than having your poi dead on at 200.

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This. By far the most likely.

The difference is to great for most other inputs, velocity would have to be eye watering and atmo wont get anywhere near it if your shooing on this this planet.. Defiantly check the click value of you scope but it would need to be double the value as VC mentioned and that is unlikely and you would have picked it up sighting in in the beginning.
400 and 500 is a little close together. I would shoot 3 shot groups: @200 to check zero then 400 then 600 and shoot all from the same position.

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Originally Posted by Fireflite

I've got Zeiss HD5 dial with dial turrets that you can try for a comparison.

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Thanks that's a very generous offer , I did wonder if it wasn't dialling correctly but the thrust of it is iv basically triple checked the zero at 200y moved back to 400y & 500y to confirm a drop of 8" & 15.5" without doing any dialling (this time round as it always shoots high going off the app or if its the scope), I will load up some more rounds tomorrow & test weather permitting .

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Originally Posted by Boaraxa

Thanks that's a very generous offer , I did wonder if it wasn't dialling correctly but the thrust of it is iv basically triple checked the zero at 200y moved back to 400y & 500y to confirm a drop of 8" & 15.5" without doing any dialling (this time round as it always shoots high going off the app or if its the scope), I will load up some more rounds tomorrow & test weather permitting .

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This is a totally level range or there is angle up or down and you are compensating for it?

Another possible explanation is your 400 yards and 500 yards, aren't.

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Originally Posted by Boaraxa

Thanks that's a very generous offer , I did wonder if it wasn't dialling correctly but the thrust of it is iv basically triple checked the zero at 200y moved back to 400y & 500y to confirm a drop of 8" & 15.5" without doing any dialling (this time round as it always shoots high going off the app or if its the scope), I will load up some more rounds tomorrow & test weather permitting .

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Eliminate as many variables as possible, dont change position, shoot all distances from the same spot/surface. There is a reason for what you are seeing, just trial and error untill you find it.

If you have known zero and bc just use the truing function as far out as you can shoot and the every thing in between is done.
Your speed seems a bit high and I will check bc on my applied ballistics software.

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Originally Posted by andyanimal31

If you have known zero and bc just use the truing function as far out as you can shoot and the every thing in between is done.
Your speed seems a bit high and I will check bc on my applied ballistics software.

Sent from my SM-G950F using Tapatalk

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It has got a g1 bc of .627

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I’ll chime in, although im reading plenty of sound advice above... accept the suggestion of investing in comrade Mao’s optic, that would be an exercise in futility:thumbsup:

From what you’ve said, something in your system is wrong, but I can’t tell you what it is exactly because I’m not able to witness your set up or methodology...

...but it doesn’t matter.

If you’ve shot the rifle and know the true drop- from a zero which you find acceptable then just adjust the inputs in the app to match what your seeing ... easiest is click value (for the obscene amounts you have mentioned)

If the gun is accurate it’s the last thing I would throw away, especially as all it can currently be accused of is “shooting too flat”

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Originally Posted by Boaraxa

Thanks that's a very generous offer , I did wonder if it wasn't dialling correctly but the thrust of it is iv basically triple checked the zero at 200y moved back to 400y & 500y to confirm a drop of 8" & 15.5" without doing any dialling (this time round as it always shoots high going off the app or if its the scope), I will load up some more rounds tomorrow & test weather permitting .

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So you confirmed your zero to be bang on at 200y, then shot at 400&500y without dialing and used a tape measure to measure poi from poa to get your 8 & 15.5 inch?

Nothing silly like you're measuring in centimeters and forgetting to convert to inches so your error is only half odd out?

You'd have to be running near 4000fps otherwise wouldn't you?

Slap up some photos when you try again.

Range finder on yards not meters etc

Here i go… Hi @Boaraxa, i have spoke with Greg (@Greg Hud) and even he got VERY surprised with the results, as we played with the data it shows your velocity is about 4300Ft/s (don't worry we definitely know about it) and as you can see everyone has the same "idea" as, "something is very wrong"… Knowing you i am 100% sure you are using "CLICKS" and not actually "MOA" to adjust, so saying it if you adjust in clicks divide your number of "CLICKS" by 4 and you shall get a more realistic "close number" to the "MOA" suggested.
My good friend, it is just something to look for as a possibility.
If i had money now (today) i would drive over and shoot with you through the chronograph and "TRIPLE" check the velocity.
I am 100% sure your rifle has nothing wrong with it and if you want to "disposal" it i will take to my "special dump" for you without a charge… Just joking my friend…

Please have a look in what i am saying and let us know… The possibility is, your scope is dialling more than it should…

Lets talk, free this afternoon if you can call in…

Mac

If he's done it without dialing though and actually physically measuring wouldn't that rule out scope? Can't even blame loose gear if it's being repeatable.

User error.....hopefully. Cheapest outcome.

Follow the screen shots of I-Sniper, Shooter and JBM-Ballistic catered for/from the information given and that "I" have as a primary developer…

Note that however they differ from each other they are very closer thou…

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HA ha..done that before !

My dear friend @Boaraxa, we haven't spoke lately but i can let you know that i "ALMOST" lost my sleep thinking about your "problem" and my suggestion "solution" is, lets try a different scope with dealing system in your rifle and make sure none of us are going crazy for a "simple" matter. You know me and how much i try to be "perfect" (you know i am NOT, 4 shots to drop a deer) but i don't think the actual problem is with your reload and or even with your Browning…
I am heading to my local 100yd range for a sight in and chronograph session this morning and if you are "free" you are more than welcome to come over for a chat and shot.

Have an awesome day as always my friend, regards to the family and keep fit as i am "almost" there… (another month or two)…

Mac

Im out this morning mate but I am heading to the big smoke thisarvo , just happen to have a bag full of veno I could drop that off ...maybe a rifle to :)
Had a good reloading session yesterday so have a good supply of ammo , if I get the chance today I will do another drop chart starting at 200 -400-500y without doing any dialling to confirm drop , there's not a breath of wind atm just need to geta hold of the cocky .

@Boaraxa any luck?

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Originally Posted by Nibblet

@Boaraxa any luck?

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Ha @Nibblet well the plot thickens , so I went back a few days ago fired 10 rounds at 200 , shots were 6"
high but I did remove the stock to loktight a screw as I put a new trigger spring & I never got around to make sure it was 100% secure , but in all likely hood our 200y zero may not have been , I tried to find the shooting spot but the cocky had sheep in the paddock so I couldn't find it, so naturally I wanted to re zero at the 200 however when I went to adjust the scope I noticed the bloody scope had moved forward , even though the ring screws had been loktighted they still came loose!! so I came home took them all off , tighted , loktighted , done rite....no on further inspection the rings somehow mount into the xbolt system had also been blasted back so after around a hundered bucks worth of ammo im back to square one , il be taking the rifle to the shop next week for them to fix or replace the mounts..these magnums can be a real pain in the ass at times.

True Boaraxa but once you have it sorted they do work a treat, good luck looks as if you have sorted the problem. Be nice to get out and use it on some game.

So to put this thread to bed or lay it down for a while !! I swapped the meopta 3-18 for a vx5 3-15 now I still cant say for certain there was anything wrong with the meopta the mounts/rings may not have been done 100% from the get go , talking to my mate the young fella at the shop that set it up may not have tightened things up sufficient but that said these magnums have a way of been hard on gear , moving forward I zeroed the new scope (thanks @Paddy79 ) at 200y then went to 400 could see the group a little to the rite so moved 1 click left then 500 , its not my finest shooting by any means but finally some success after chasing my tail for some time , I relied solely on the app for the 6 shots , the app said 3.7 moa at 400 so I adjusted 3moa & 3 clicks for 500 it said 5.9moa so I rounded it to 6 that said the 500 group is a touch higher .
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