Long Range Ballistics

[leo]

I brought up a point in another thread that a bullet with a higher sectional density, Ballistic coeficient will fly flatter farther than one with a lesser . My reloading data doesn't show much beyond 500yds. But in my data , a 160gr,btsp with a much higher b/c actually drops less at and assumably beyond 500yds than say a 140 gr. There is some genuine 1000 yd. marksman and reloaders on this site who know more about long range ballistics than I do , Please tell me if I am incorrect. From my 25 + years of reloading I was always under the impression that a lighter projectile sheds energy quicker than a heavier one

[Andrzej]

Originally Posted by leo

I was always under the impression that a lighter projectile sheds energy quicker than a heavier one

30-06 factory 220 gr will deliver 1000ft/lb up to 350 yards,
150gr up to 400y.
BUT
225gr from 338 Win Mag will carry 1000 ft/lb up to 700 yards.

Leo get yourself one of the ballistic programs , I use Remington Shoot, free from Remington site it will let you see what happens up to 1000 yards /meters trajectory, energy,
I would play with this and confirm at the range.

You can play with numbers.

[lclund1946]

Originally Posted by leo

I brought up a point in another thread that a bullet with a higher sectional density, Ballistic coeficient will fly flatter farther than one with a lesser . My reloading data doesn't show much beyond 500yds. But in my data , a 160gr,btsp with a much higher b/c actually drops less at and assumably beyond 500yds than say a 140 gr. There is some genuine 1000 yd. marksman and reloaders on this site who know more about long range ballistics than I do , Please tell me if I am incorrect. From my 25 + years of reloading I was always under the impression that a lighter projectile sheds energy quicker than a heavier one

I suggest that you get yourself a ballistics program such as RCBS Load and do some comparisons. What you are suggesting is kind of like the myth that lighter bullets drift less in the wind than heavier ones. When you start doing some comparisons you will find that Ballistic Coefficient and Velocity determine Terminal Energy, bullet drop and wind drift.

Here is a comparison of a 140 grain and 168 grain bullet that will shed some light on the subject:
BERGER - 6.5mm, 140 VLD, BC .633, MV 3200fps, ME 3182.9 ft. lbs., 1000 yd energy 1052.8 ft. lbs., 1000 yd drop 216.49" and 1000 yard drift in a 10 mph wind is 53.18".
BERGER - 7mm, 168 VLD, BC .617, MV 3200fps, ME 3819.5 ft. lbs., 1000 yd energy 1223.4 ft. lbs., 1000 yd drop 219.37" and 1000 yard drift in a 10 mph wind is 54.98".

If the BC would have been the same then the 1000 yd drop and wind drift would have been exactly the same. But because the 6.5 bullet has a slightly higher BC it drops less and has less wind drift. As far as shedding energy faster the 6.5 bullet retained 33.07% of its energy while the 7mm bullet retained only 32% of its energy. If the BC would have been the same then the percentage retained energy would have been the same. As the 7mm bullet started out with more energy at the muzzle it has a corresponding higher terminal energy. Along with that comes more recoil.

[leo]

Okay what you guys suggest makes some sense. But a 139 gr 7mm hornady vs a 162 gr 7mm hornady ,at 500 yds the difference in bullet drop starts to favor the 162 . Does that not mean that at say 800 yds the actual flight arc is less pronounced in the heavier, higher bc bullet. Will the bullet drop not be less than the 139 gr,both assuming a 200 yd 0 . The 162 gr at 3000fps, the 139gr at 3200fps or max loads for the individual gun ?

[Andrzej]

Leo

go to

http://www.gsgroup.co.za/download.html

Download this presentation (it is on my Desktop all the time)

there is a lots of information and this will answer your questions + some.

Andrew

[bingo1010]

higher bc bullets will drop less/ retain more energy than lesser bc bullets. that about sums it up. you can move a lighter bullet faster and this will "mask" the difference for a short while but the farther out you go the more the diff will be....totally favoring the higher bc bullet. under 500 you won't see much diff between them.

[SHORTMAG]

Take a 300 win mag shooting two 180 gr reloaded rounds at 500 yards. Using a PSP tip in one case and a Ballistic tip in the other.....the ballistic tip will have approx 450+- Foot pounds MORE energy than the PSP at that distance. That's quite a bit more by just swapping a lowly old tip!!!

Originally Posted by bingo1010

higher bc bullets will drop less/ retain more energy than lesser bc bullets. that about sums it up. you can move a lighter bullet faster and this will "mask" the difference for a short while but the farther out you go the more the diff will be....totally favoring the higher bc bullet. under 500 you won't see much diff between them.

Exactly. It all comes down to time of flight. The higher BC bullet gets there faster because it retains velocity better. Less time in the air means gravity has less time to act upon it which means less drop. Gravity has the same effect regardless of the projectile BC, size, weight or shape, it's just the one with the higher BC gets there faster....at very long ranges of course.

It's basically the same thing with a side wind. The faster it gets there, the less it gets blown off track.