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Old September 23, 2012, 08:07 PM   #1
jabames
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.30-06 bullet drop

Hello,

Say I'm wanting to shoot out to 500yds/m, I'm looking up ballistics just for a Remington core-lokt psp in 18 grain weight says it drops 72.8 inches. Roughly how much MOA should I go up from my 100m zero? My barrel is 22 inches, so I'm thinking they used a 24 inch for the data so I expect a small amount less muzzle velocity than the mentioned 2700fps. I'm probably gonna switch to Core-lokt Ultra bonded for the small amount more of BC nwhich is about almost twice as much as the standard core-lokt pointed soft point round. Hahah maybe I'll get some factory loaded Remington Swift Scirocco for the .500 BC seems way more efficient than any of the core-lokt rounds thus equals less bullet drop, plus that round is bonded so that includes also better terminal performance...lol plus a tip and boattail.
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Old September 23, 2012, 08:24 PM   #2
Brian Pfleuger
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Without knowing your actual velocity and without actually shooting, it's just a guess. You can subtract 25-50fps per inch of barrel length from KNOWN velocity, but numbers published on a box aren't what your guns does. Without a chronograph, your just guessing.

To get some general ideas, use something like JBMs trajectory calculator.
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Old September 23, 2012, 08:27 PM   #3
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Find a chronograph you can use to get the exact muzzle velocity. Then you can put your BC ,weight of the bullet, velocity, zero yardage and alltitude in one of the many online ballistic calculators. You can deduct 25fps for every inch of barrel you are short for a ballpark it should come out close. The only way to know for sure is to chronograph it some barrels are faster or slower then others.
Good luck.
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Old September 23, 2012, 08:29 PM   #4
jabames
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lol I'm "guessing" at 500m I go up about 10-12 inches/MOA from my zero with a 180 swift scirocco round but idk.
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Old September 23, 2012, 08:34 PM   #5
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Try coming up 13 MOA from your 100 yard zero to 500

These are 1 moa clicks

100-200 2 clicks
200-300 3
300-400 4
400-500 4
500-600 4
600-700 5
700-800 6
800-900 6
900-1000 7
1000-1100 7
1100-1200 8

If you wanted to do the math: A MOA is 1.047, at 500 yards it would be 5 X 1.047 = 5.235 then divide your 72.8 by 5.235 = 13.9 clicks,

You should use 14 MOA Clicks

The Chart I posted above is for most 308/30-06 rounds.
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Old September 23, 2012, 08:39 PM   #6
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Sounds like a good idea, I can start up to 14 MOA then go up or down if I miss etc.
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Old September 23, 2012, 08:39 PM   #7
Reloader 17
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It really depends on your zero yardage and exactly how much drop the bullet has out of your rifle. If you have a 250 yd zero you wouldn't have to compensate as much as you would for a 100 yd zero. Hope this helps.
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Old September 23, 2012, 08:43 PM   #8
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thanks, I usually shoot when their is little wind, sometimes it gets windy so we cant hit at 500m. But for hunting applications in the field the wind wont stay still and conditions wont be perfect.
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Old September 23, 2012, 09:08 PM   #9
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Not only are advertised velocities grossly overstated (and sometimes understated)...advertised BC's are too. Many are off by as much as 10%, most are off around 4-5%.

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA554683

Berger bullets are an exception...Berger thoroughly tests theirs, but not everybody has Litz as their Chief Ballistician.

Last edited by Ridgerunner665; September 23, 2012 at 09:14 PM.
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Old September 24, 2012, 12:20 AM   #10
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They don't overstate what they get, only report numbers they actually get with their test barrels. Of course the manufacturers test barrels are usually better quality with tighter chambers and more precise tolerences in the barrels than the average hunting barrel. Some rifles will come very close to advertised velocities, others not. I've seen guns with equal length barrels have more than 100 fps difference with ammo fired from the same box. I've seen a 22" gun shoot the same ammo faster than another 24" gun. This is why it is necessary to shoot the ammo you are going to be using over a chronograph so you know how fast it is in your gun.

Same with BC. They don't misrepresent them. There are different ways to measure it. Bergers method is probably more accurate and they list 2 different BC's on their box, measured 2 different ways so buyers can have comparable numbers to compare with other brands.

BC also changes as velocity changes. A bullet with a listed BC of .475 might be .475 at 3000 fps, but as the bullet slows down at longer range the BC also changes. The online programs used to calculate trajectory and energy don't compensate for this and often show faster bullet speed at long range than you will actually get. Those are fine for getting an idea of what to expect, but there is no subsitute for actually shooting at those ranges to know for sure where you are going to be hitting.
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Old September 28, 2012, 06:54 AM   #11
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Sierra Bullets also tests their bullets for BC using time of flight between two points at different starting velocities. They've been doing that for decades. Sierra uses the G1 drag model while Berger uses the G7. Sierra lists more than one BC for their bullets in several velocity bands. Berger uses only one. They're both very precise for their software and therefore excellent for calculating drop and drift numbers.

Some ammo companies use SAMMI spec test barrels clamped in solid mounted receivers for muzzle velocity and pressure numbers. Others use whatever factory rifle barrel they've at hand fired from a bench. The differences in muzzle velocity between two people shooting the same rifle and ammo from a bench can vary as much as 100 fps. And solid mounted test barrels always give higher muzzle velocities; they don't move backwards in recoil while the bullet goes through them. And one's personal rifle probably has different bore and groove diameter and length dimensions than the factory barrel has. To say nothing of the differences in primer, powder, case neck tension and a few other things involved.

Scope makers use slightly different mechanics for their click values. Some use the original MOA numbers of 1 inch per hundred yards estabilshied by the shooting sports over a century ago. Others use the more recent trigonomic value of 1.047 inch per hundred yards. Either will vary as much as 5 to 10 percent depending on the exact focal length of all the lenses in each of several lens groups in a scope as well as the mechanics used to move the target image on the reticule. Unless one accurately measures their click values, they should be prepared to accept some inaccuracies.
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Old September 28, 2012, 07:14 AM   #12
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2 for 200 (100 to 200yds)
3 for 300 (200 to 300yds)
12 for 600 (300 to 600yds).

^
this works well enough with most of the 223/308/30-06 sort of cartridges (modern stuff--not wildcat or magnum).

so I'd go 2 + 3 + maybe 8 = 13 minutes. Ought to put you on paper.
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Old September 28, 2012, 07:35 AM   #13
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What I found, messing around with my 500-yard range:

26" barrel, handloads with Sierra bullets. 150-grain SPBT; 165-grain HPBT, and 180-grain SPBT.

I started out with my usual deal of 150-grain bullets, two inches high at 100 yards. I'd "guesstimated" in earlier shooting for a four-foot drop and hit right at dead center on the hanging steel plate.

I came up 32 clicks, eight inches, at 100 yards from the original two inches high. That put me close to center for all three loads--which was rather surprising.
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Old September 28, 2012, 07:35 AM   #14
jabames
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I normally zero my rifle at 100m, and shoot at metal targets whether they be circles or a ram-shaped target at 500-600m. If I get a chronograph and it measures to what ever the muzzle velocity, how do I determine how much it drops out to 500-600m. Is there like a special mathematical equation of sorts to figure this out?
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Old September 28, 2012, 07:41 AM   #15
Art Eatman
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I've always used the Sierra tables in the appendices of their reloading book to get a good idea of drop for various zero setups. IMO they're the best to figure out the trajectory of which bullet at what muzzle velocity for a given sight-in distance.

You can figure the muzzle velocity "close enough for government work" from the reloading tables, if you don't have a chronograph.
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Old September 28, 2012, 08:46 AM   #16
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Quote:
You can figure the muzzle velocity "close enough for government work" from the reloading tables, if you don't have a chronograph.
"close enough for Government work" is a pretty elastic standard, depending upon the particular Agency or Dept. (and individual: Paging Lon Horiuchi....) in question......

If you want to hit your target the first time, you really need to know your load's muzzle velocity out of your rifle, and it's BC..... and exact range to target.

Anybody with a spotter and a set of binoculars can walk rounds onto paper..... you could do that and write down your ups....
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Old September 28, 2012, 10:23 AM   #17
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Quote:
I've always used the Sierra tables in the appendices of their reloading book to get a good idea of drop for various zero setups. IMO they're the best to figure out the trajectory of which bullet at what muzzle velocity for a given sight-in distance.
The problem is tables, any tables, is that they are only accurate if your rifle matches theirs, in their conditions, i.e. 1.5" sight height at sea level.

I don't think any of my rifles have a sight height of 1.5", and my favorite range is 4200', although there is a closer one that is about 5500'

A good ballistics program, like http://www.jbmballistics.com will give you more precise information, which you can tailor to your environment, and the more accurate information you put in, the better results you get out.

And for the record, if you put in 1.5" at sea level, JBM's results match the table in by Sierra book.
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Old September 28, 2012, 11:46 PM   #18
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Granted that Old Pet and I had been "all married up" for some thirty years, but my first shot at 500 with a 200-yard zero hit six inches low at 5:30. The next was one inch low at 6:00. I had guesstimated four feet of drop, and held two feet upwind.

Reasonably good government work, I thought.
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Old September 29, 2012, 05:51 AM   #19
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OK I'm kinda new at this long range shooting but I'm going to give this a try .Please anybody correct me if I'm wrong thanks . According to the numbers you gave . I get 14.4 MOA drop at 500 yards . That is 57 clicks up if your scope has 1/4 per click and your zero is at 100 yards . None of my scopes have that much adjustment . So I would need a BDC or Mil-Dot reticle . I like and use the Mil-Dot . I would adjust my elevation up 17 clicks and hold on the 3rd Mil-Dot for a total of 14.36 MOA . I think
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Old September 29, 2012, 08:37 AM   #20
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Forget that, I don't think I have seen a scope without 16 MOA adjustments, but if you don't have that, you need to change your bases.
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Old September 29, 2012, 04:16 PM   #21
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Yes , but that 16 MOA adjustment is total . Thats 8 MOA up and 8 MOA down , Yes ? I also agree If your only going to be shooting long range with that rifle you would want that elevation built in to the scope or mounting system . That way you can have the rifles zero at 500 yards and still have the scopes full range of adjustment 8 up and 8 down
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