Home Forums Hunting & Shooting Long Range Hunting G7 BC for 6.5 mm 140 gr Nosler Accubond??

Hi all
I've discovered the Nosler Custom 140 gr Accubond is excellent factory ammo for my 6.5 mm Tikka T3 LS producing consistent sub MOA performance. I have now laid in a supply of this ammo as I no longer hand load.

I am currently making up a range card to hunt river coulee mules using one of the ballistic calculators available online (JBM ballistics). The G1 BC for this bullet is advertised as .509 on the Nosler web page but my research indicates that the G7 BC may be the the more accurate one to use when plotting the Trajectory.

Can anyone help me out on this as I don't seem to be able to find out what it is online?
Also since I no longer have access to a chronograph I have chosen to use 2650 fps for the velocity input as I think this would be close to the actual velocity out of my rifle. It is the velocity advertised on the box of ammo. Does this sound in the ball park for a 22 inch barrel??

Thanks to all who reply.
Any help on this would be appreciated.

Just use the G1 and your velocity and run the numbers, next run some down range at different yardages to check your drops, without a chrono you may have to make adjustments to your range card as the velocity may not jive, but you can get it worked out!

.249

Yes, I plan on doing exactly that, although the range I shoot at is a little limited for long range yardages.
I am now simply looking at a good place to start at (MOA) on my elevation dial so as to conserve the ammo which is in limited supply and costly where I live but point taken - thanks!!

Maybe you know someone with a chrono that would help you get your velocity figured out, that may help conserve ammo, but the LR game can sure put a hurt on a supply of ammo...have fun!

Thank you - That's the number (G7 BC) that I'll use in the program and see if it works on the range.

The G7 doesn't help much until you are way out there! Knowing your actual velocity is far more advantageous.

While G1 or G7 never killed anything the G7 BC is a better number for building an accurate drop table with this type bullet. It is valid for a table that is calculated for any distance beyond your zero. Not just "way out there".
Now, without having a valid velocity number the OP is wasting his time on a table using either G1 or G7.

Perhaps - although I did vary the velocity in the program 50 fps just to see if it
made any real difference and the numbers still seemed to be within 1/2 MOA at 500 meters.
At any rate, I have to work with the info I've got available and I think I have enough for a good starting point at least. The goal is to build a reliable range card out to 500 - 600M which I think I can squeeze out of my local range.

My point was that the G7 is the least of his concerns if he doesn't know his velocity.

Contrary to a lot of hype there's no significant difference between G1 and G7 between 3100 fps down to 1800 fps. Those who don't agree can test it for themselves. Just plug OP's G1 BC of 0.509 into whatever program you trust and then do the same test changing only to a G7 BC of 0.255 (half the G1 BC) and look at the down range values.

If you use 2650 for MV you'll see the G1 and G7 give the exact same drop out to 550 yards where the velocity drops to 1778 fps and the drop difference between G1 and G7 are within an inch out to 850 yards regardless of the zeroed range. A load with a MV of 3100 fps using this same bullet would have the same drop to within an inch out past 1000 yards.

While the G1 and G7 drag functions are based on bullets that look radically different to the human eye, they look nearly the same to the wind between 3100 down to 1800 fps and remain similar enough down to the transonic velocity range that there's no real world difference for most shooters.

Just use the Nosler G1 and adjust your MV and the BC values to best match your actual shooting results.

Yes Maclorry that is the plan although I will run both the G1 and G7 values.

I suspect even if I knew the exact velocity in my case there might still be a little bit of fudging involved to get the real world range card to exactly line up to the program values as there are so many variables out there and maybe even a sophisticated program like JBM cannot account for them all.
I'll probably vary the velocity in the program until I'm close.