Bullet Drop?

There are a bunch of ballistic calculators and charts on line, just google search them. Many of them are free.

papajoe222 said:

I'm just now delving into shooting ranges beyond 100 meters and was wondering how to estimate bullet drop. I found a formula for determining approximate drop that I can do in my head, but the numbers I come up with don't seem realistic to me. eg. my pet load for 168gr .308 Win. runs at 2500fps. my calculation comes up at just over 8in. drop at 200yrds. and 23in at 300yrds. Does that sound about right, or am I way off on my calculations? I don't want to waste time and ammo attempting to get on paper.

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As a general rule, it is 2 MOA from 100 yards to 200 yards, and 3 MOA more from 200 yards to 300 yards with a 308 Win. That will get you in the black, but if you want to be in the center, you are going to have to shoot at distance. There absolutely no substitute for actual groups to determine zero's. Some of the worse experiences are with shooters who arrive at a mid range or 1000 yard match with only book values for zeros. The poor pit pigs pull and pull, the guys on the line offer "Aim high", "aim left", "aim at the berm!", all in an attempt to figure out which direction the bullet is going.

Need to know the BC of the projectile, speed, sight height and distance you want to set the zero.

Take the numbers and plug them into a calculator like this one.

https://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

And you get this.

On Android, I use Shooting Solution. It is a free app, easy to use, provides a lot of information, but, as said, it will only get you close. Verification by actually shooting those distances will be needed to confirm before actually using those numbers.

https://play.google.com/store/apps/details?id=com.casey.ShootingSolutionFree

badkarmamib said:

....it will only get you close. Verification by actually shooting those distances will be needed to confirm....

https://play.google.com/store/apps/details?id=com.casey.ShootingSolutionFree

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This cannot be stressed enough. This is true for a number of reasons; as no two rifles are exactly alike, no two lots of ammo/powder/primers/brass are exactly alike.

I have two High Power Metallic Silhouette rifles chambered 6.5x55 SM. Their impact points on the rams at 500 meters using the same batch of handloads center of impact is about 5 1/2" - 6 1/2" different when using a 200 yard zero. This also can vary quite a bit depending on temperature and atmospheric conditions.

For big game hunting zero at 100 yards with almost any modern cartridge shooting pointed bullets and you'll be 3-4" low at 200 yards, 12-15" low at 300, and 30ish " low at 300. The difference between your 308 and a 300 WM at those ranges won't be enough to cause you to miss a deer or elk size target. We're talking about a 10"-18' kill zone and even if the 300 is a couple of inches flatter it won't matter with a target that size.

You can enter the data into one of the online programs and print out the results if you want more precision.

This becomes more of an issue if you're trying to hit smaller targets or game, or if you start shooting beyond 300 yards. Bullet drop becomes much more arched and flatter shooting cartridges help at longer ranges. Beyond about 300 yards a range finder starts to be necessary too. If you guess that a deer is 250 yards away and it is actually 300 you'll probably still get a hit. But if you guess that a deer is 350 yards away, and it is really 375 that is enough for a complete miss.

[QUOTEFor big game hunting zero at 100 yards with almost any modern cartridge shooting pointed bullets and you'll be 3-4" low at 200 yards, 12-15" low at 300, and 30ish " low at 300.][/QUOTE]

And if big game hunting is your reason for needing differing drop info, you can sight about 1 3/4 inches high at 100, putting you about dead on at 200, and about 9 inches low at 300. This is true of the vast majority of normal hunting calibers. Temperature, humidity, and lay of the land (uphill downhill) all can have slight impact, but not enough to get out of the kill zone.

papajoe222 said:

I'm just now delving into shooting ranges beyond 100 meters and was wondering how to estimate bullet drop. I found a formula for determining approximate drop that I can do in my head, but the numbers I come up with don't seem realistic to me. eg. my pet load for 168gr .308 Win. runs at 2500fps. my calculation comes up at just over 8in. drop at 200yrds. and 23in at 300yrds. Does that sound about right, or am I way off on my calculations? I don't want to waste time and ammo attempting to get on paper.

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Those numbers don't seem too far off to me. It's only a waste if you don't value what you learn from the experience.

Slamfire said:

..That will get you in the black, but if you want to be in the center, you are going to have to shoot at distance. There absolutely no substitute for actual groups to determine zero's.

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While I was developing some loads for a .303 I used a chronograph to get actual velocity, then entered all the information asked for into an online ballistics calculator. After printing a couple pages of results, one set for a 100 yard zero, another for a 200 yard zero, I took a B-27 target to the range to see how close the model was. I put an orange, three inch sticker on the target and replicated the inquiries I entered in the ballistics calculator with five shot groups. One group each at 100, 200, and 300 yards with a 100 yard zero, another set of groups with a 200 yard zero. While the actual shooting results matched those predicted by the calculator, it was much more informative. Not only did I get to see the drop, but also the way the group spread out in general. I don't consider that a waste at all.

patmccoy said:

[QUOTEFor big game hunting zero at 100 yards with almost any modern cartridge shooting pointed bullets and you'll be 3-4" low at 200 yards, 12-15" low at 300, and 30ish " low at 300.]

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And if big game hunting is your reason for needing differing drop info, you can sight about 1 3/4 inches high at 100, putting you about dead on at 200, and about 9 inches low at 300. This is true of the vast majority of normal hunting calibers. Temperature, humidity, and lay of the land (uphill downhill) all can have slight impact, but not enough to get out of the kill zone.[/QUOTE]
I agree with this. 100yd zero makes no sense with modern scoped rifles in anything that shoots as flat or flatter than a 308.
I sight 30-30 and muzzleloader at 100 because I won't shoot beyond 200 yards with them.

OP, you should be calculating point of impact change from your zero distance. This gives you a better reference.