.308 bullet drop? Help w/ trajectory table


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skipbo32
August 25, 2010, 02:37 PM
can anyone tell be the difference in ballistics of the 150 grain .308 and the 168 grain .308? or tell me where i can get a trajectory table to learn the difference? the reason i ask is because i have a leupold mk 4 w/ a bullet drop dial marked for a 168 grain bullet....but i shoot a 150 grain.

i would imagine that the dial would start to be inaccurate after about 300yds since a 168 grain drops faster than my 150 grain.

or should i just use the dial with the marks that it has regardless of the different grain? is a 168 that much different than a 150 grain?

any help would be great, thanks.

http://i87.photobucket.com/albums/k141/skipbo32/DSC03820.jpg

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MinnMooney
August 25, 2010, 03:32 PM
A few things are missing in you inquiry :

1.) Velocity of these two bullets out of YOUR rifle.

2.)Atmospherical conditions during an average day of shooting. (Especially needed would be temp & elev.)


Federal Cartridge has an excellent ballistics table (free & on-line) that will probably answer all of your questions.............

http://www.federalpremium.com/resources/ballistics_application.aspx

I hope this works for you.


P.S. Your 168 gr bullet may not drop faster than the lighter bullet. If the heavier bullet has a much better ballistic coefficient (B.C.), it may actually drop less over the longest distances.
If all things are equal, i.e., shape, B.C. and S.D. (sectional density) then you, of course, are correct... the heavier bullet will drop further in any given distance.

My favorite is Sierra bullet's program called Infinity but you'd have to by it for about $30+.

Jim Watson
August 25, 2010, 04:37 PM
Best to shoot the gun and make a conversion table for your ammo and your barrel:

On at 400 requires dial to be set at 350 or some such.

Or contact Leupold and see how much they will charge to cut you a new dial.

DIM
August 25, 2010, 06:00 PM
all the ballistic calculations you might require you can find on JBM website, its really good and I use it every time! http://www.jbmballistics.com/ballistics/calculators/calculators.shtml

rcmodel
August 25, 2010, 06:16 PM
Change the elevation knob.

You need to shoot your rifle, with your loads, and record the drop at different ranges.

Then The Leupold Custom Shop can make you an elevation knob calibrated for your loads in your rifle.

http://www.leupold.com/corporate/resources/faqs/#questionTwo

rc

cbmax
August 25, 2010, 07:01 PM
Just as a point of comparison my .308 bolt action rifle drops about 14 inches from it's one hundred yard zero when shooting 168 grain Sierra Match Kings.

Your mileage may vary.

CB

DIM
August 25, 2010, 07:05 PM
without correct chrono reading what muzzle velocity is we are only playing guess game here, any calculator will require starting speed to measure bullet drop

USSR
August 25, 2010, 07:13 PM
First thing you do in buy a chronograph and run whatever load you intend to use across it. Once you know your velocity, there are free exterior ballistics programs available, and the velocity and BC of your bullet (available from the bullet manufacturer) plugged into the software will give you a "rough" drop chart. Then, as previously mentioned, you will need to shoot at at least some of the distances to tweak your drop chart data based on your actual results.

Don

StoneDog
August 25, 2010, 07:28 PM
MinnMooney said:
If all things are equal, i.e., shape, B.C. and S.D. (sectional density) then you, of course, are correct... the heavier bullet will drop further in any given distance.

Not to be picky, but this is only true when the lighter bullet has a higher velocity in which case all things aren't equal.

velocette
August 25, 2010, 07:33 PM
Go to: http://www.handloads.com/calc/

You will find answers to all your questions.

nastynatesfish
August 26, 2010, 12:07 AM
Try www.biggameinfo.com. There calculators are awesome.

blackops
August 26, 2010, 01:48 AM
I took Don's advice a while ago and it worked out well. Get a chrono, plug the data into a ballistic software program, and field test it.

kmcintosh78
August 26, 2010, 09:02 AM
This is a good site to. But, just as everyone says, you should go out and shoot it. Just like my M14 does awesome with Port Surplus, yours will vary. Same with ballistics.
http://www.winchester.com/LEARNING-CENTER/Pages/Ballistics-Calculator.aspx

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