Thread: 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



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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!

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

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

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!

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?

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



Sent from my SM-G965F using Tapatalk

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

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

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?

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 .

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 .

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.

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 .

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.