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Old March 18, 2013, 04:25 PM   #1
Metal god
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How to calculate ?

How do you calculate the max hight of your bullets travel at let say 1000yds . Firing position and target are at the same elevation If your bullet is going to drop 24' at 1000yds . That does not mean the the bullet will top out at 24' above the ground/target , right? or does it ?
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Old March 18, 2013, 04:32 PM   #2
Bart B.
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Use some ballistic software such as Bergers; it's a free download.

Bullet drop's calculated from the bore axis. If a bullet drops 24 feet from a horizintal bore axis at 1000 yards, it'll probably have a maximum ordinate (height above line of sight) of about 8 to 9 feet. The high point will be at 500 to 600 yards down range. The bore's pointed at a point 24 feet above the 1000 yard target; at 500 yards, it's pointed about 12 feet above the line of sight. After the bullet leaves the barrel, it's always below the bore axis; it starts falling as soon as it's no longer in the barrel.

A good "rule of thumb" for longer ranges is, the maximum height above the line of sight is equal to about 1/3rd of the bullet's drop at the target.
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Old March 18, 2013, 04:49 PM   #3
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If you have an iphone or android phone there is a nifty app called Strelok.

You input the relevant data, and it will provide you ballistic tables telling you the drop for a given angle.

For popular scopes on the market, you can find your scope in the program and it will show you holdover for a given distance. It will also tell you how much to adjust your scope or how much to holdover. Lots of features, you can program in and save various bullet weights at different velocities.

It is also free, at least it is on android, so it is at least worth checking out. Good user interface and a good free ballistic calculator.
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Old March 18, 2013, 05:15 PM   #4
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Cool thanks Bart. Went to Bergers website . They are re-programming there ballistic calculator right now . When is becomes available again I'll down load it .

I've been using the Hornady calculator and shooterscalculatoer.com .
What drag function should I have it set at for 30cal 168gr or 175gr smk ? I've been using G1 is that the best ?

EDIT: just down loaded that app for my iPhone it was $5. It looks pretty cool and it even has the vortex reticle I use .
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Old March 18, 2013, 06:31 PM   #5
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Talking about Strelok or another program with the edit?
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Old March 18, 2013, 06:34 PM   #6
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I downloaded iSnipe on my iPad. Works fine. I can't remember whether or not it was free.
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Old March 18, 2013, 07:05 PM   #7
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alex0535

Strelok and with out using it I like it the best out of all the calc apps I've researched . I've even down loaded a few others to my phone . The Strelok seems to work the best as far as ease of use , cost and amount of things it does . I love the feature that lets you change the magnification on your scope/reticle just by using the slide bar . Can't wait to see if it's accurate .
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Old March 18, 2013, 07:17 PM   #8
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Go to Sierra Bullets web site then to their Match King bullets. All of their BC's are listed. Use their G1 value in Berger's software that's in the velocity range used; .490 for example for their 30 caliber 175 HPMK.

http://www.sierrabullets.com/index.c...1&displayAll=1
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Old March 18, 2013, 07:32 PM   #9
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I just have the free version, think it lacks some of the features of the paid one. Very functional app though, lots of features, easy to figure out. It has been good for me at the distances I shoot, but I don't usually shoot far enough to really test this program fully.

And apparently if you have a reticule that is not part of the program you can email the programs creator ask him to do it and he will program it and update the program.
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Old March 18, 2013, 08:21 PM   #10
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Thanks again Bart , That is what I've been doing . I put in G7 once and the calculations changed alot . All of a sudden I could shoot a mile with my 308 . I knew that was not right so I thought I would ask to be sure .

Alex : Yea I have the vortex BDC reticle . As you slowly change the magnification on the app the hash marks change to the correct distance . The only bummer I see so far is I can't get them to line up perfect to to the 100th yard marks . closes I can get is 100yd zero , 187yds next line then it,s dead on 3 , 4 , and 500 yards line up perfect to the following hash marks @ 17-1/2 x magnification . That is of course matched to the factory specs of 168gr Federal GMM and is what I shoot till I start reloading .
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Old March 18, 2013, 08:44 PM   #11
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Metal god, keep in mind that those reticules on your scope for bullet drop may or may not be correct for the velocity your rifle shoots that Federal ammo. There could easily be a 100 fps difference.

And they're only good for one elevation above sea level and one set of atmospheric conditions.

Changes from what they're calculated for could mean several MOA's of error at the longer ranges. There's a difference in a .308's bullet drop at 1000 yards going from 600 feet to 6000 feet elevation of about 5 MOA.
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Old March 18, 2013, 09:04 PM   #12
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Bart : you are correct and I can't wait to start reloading so I will know all the velocity for each load . I have some stuff back ordered and a few other things I still need to buy for reloading . One Thing I still need to get is a chronograph. I was thinking it would be one of the last things I get . My thought on this is , until I can shoot dime size groups with my had loads I don't really need to know the velocity . I don't need to know the velocity of loads I never intend to use right or should I keep a log of every shot fired once I start reloading ?
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Old March 19, 2013, 05:43 AM   #13
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You don't need a chronograph to get zeros at different ranges. Regardless of the group size you shoot, just get a zero at different ranges. Then write them on a label that ends up stuck on your scope.

If you use two different loads, you'll need two different labels; put on the one that matches your load. You'll also need different labels for the same load when used in different ambient temperatures and elevations. Keeping a log for different condtions and loads will help establish really accurate zeros for each.
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Old March 19, 2013, 01:30 PM   #14
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Excellent calculator here, with a database of published BCs from just about everyone:

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

Just estimate your velocity, put the zero range at 1000, and set the table step to 25, you can see where the apogee is.

I just rant it for the .308 180 SMK @ 2600 fps, and it peaks at ~575 yards, at +150.8", or roughly 12 1/2 feet.
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Old March 19, 2013, 07:59 PM   #15
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Quote:
How do you calculate the max hight of your bullets travel at let say 1000yds . Firing position and target are at the same elevation If your bullet is going to drop 24' at 1000yds . That does not mean the the bullet will top out at 24' above the ground/target , right? or does it ?
Your maximum height above line of sight will not be 24 ft but 1/4 of 24 ft, about six ft.
It takes the exact same time for something to go straight up, decelerate to a stop, and reacelerate to it's initial velocity back down as it does to fall four times as far from a dead drop.
Formula for freefall distance. distance in ft = 16.1 * (time in seconds)squared

A bullet spends the first half of its time of flight gaining altitude until gravity brings the altitude gain to a halt, then it spends the second half of its time of flight acellerating back down. Since 1/2 squared = 1/4, the maximum rise is 1/4 of the freefall distance.

In order to have a total drop of 24ft, your bullet would have to get to the target in 1.22 seconds.

Last edited by B.L.E.; March 19, 2013 at 08:28 PM.
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Old March 20, 2013, 07:40 AM   #16
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B.L.E., all the software I've run shows the bullet spends about 45% of its flight time rising to maximum height (near 3/5ths of target range, not half way) and about 55% falling to the target.

And max height above line of sight's about 1/3 of bullet drop below bore axis at target range.

Time of flight for a bullet dropping 24 feet (288 inches) below a horizontal bore axis at 1000 yards is about 1.344 seconds in standard atmospheric conditions.

Do you think all that software's not accurate?
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Old March 20, 2013, 04:30 PM   #17
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1st Article

2nd Article

Both articles are on what it takes to make a 308 cartridge proficient at 1,000 yards.

+1 on using JBM Ballistics for calculating trajectories.
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Old March 20, 2013, 04:50 PM   #18
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Geo's reference to Salazar's articles is a good idea. Regarding those fantastic WCC cases, I've got about 1,400 WCC58's, about 1000 once fired and the rest fired about 12 times; good for at least 20 more. Also have about 400 new, unfired WCC60's. I'd sell them and pay shipping if I had a good offer. Both types have probably been used to set more records and win matches than any other two makes and types.

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Old March 20, 2013, 06:09 PM   #19
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Quote:
From the article 1

Get to the range with an adequate supply of sized brass, the primers, powder and bullets you intend to test, and get to work. Work up to your magic number velocity and record the charge weight and powder type and lot number. From there, if there are no adverse pressure signs, you can continue varying your charge weight as you seek accuracy, but remain vigilant for pressure signs!
This seems to say work up the velocity first then work on the accuracy . In the article he is talking about palma match loads so I assume he is getting that 2800+fps out of a 30" barrel . It also appears he is barely to the number he needs for all conditions with that 2800+ . I don't think I'll ever get my 24" barrel safely anywhere near that velocity .

Although I want to shoot 1000yds with my 24" 308 . That Will not be the distance I will be shooting most of the time . Realistically I will be shooting 3 to 6 hundred yards most of the time . There are very few places to shoot 1k in southern California . I can find BLM land to about 600yds no problem so that will be the longest I shoot most of the time .

What my plan is and or was is to use 175gr SMK . Work up a load that can shoot 1k accurately and consistently and use that for all my shooting .

1) Will I be able to get my 24 " barreled 308 to shoot 1k accurately and consistently ? ( assuming I do my part bla bla bla )

2) if so will that load likely work for all ranges from 100 to 1000 yards ?
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Old March 20, 2013, 07:35 PM   #20
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To get 155's out the barrel fast enough to remain supersonic through 1000 yards, you'll need a 30" one to shoot 'em at least 2950 fps. 175's will be just fine leaving at 2600 fps.

If your barrel's groove diameter's a few ten thousandths smaller than bullet diameter, your chances are excellent the 175's will shoot very accurate.

1) You will be able to get my 24 " barreled 308 to shoot 1k accurately and consistently. Try 43 to 44 grains of IMR4064.

2) That load will likely work for all ranges from 100 to 1000 yards.
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Old March 20, 2013, 08:26 PM   #21
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Thanks , 8lbs of IMR 4064 is one of the things on back order . I have winchester primers now and some remingtons on back order . I have a couple hundred once fired federal GMM brass . 175gr smk and 178gr Amax bullets . this will be what I start with .
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