I am going on a trip this week, and can only sight in at 25 or 50 yards:banghead:, for various reasons I cannot sight in at my regular place due to scheduling, new rifle and its boresighted, 150 gr 3,375 fps and if I'm 1.03'' high at 100 yards I'm dead on at 200. How many inches high or low would I need to be at 50 or 25 yards to be dead on at 200?
Sighting in at 25 or 50 yards??!?
- Thread starter Ace15
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You don't need to know the caliber. You need to know the Ballistic Coefficient of the bullet. You can usually look it up if you know what ammo you have.
If you have the weight, velocity, and the B.C., and the sight height above the bore, you can use this calculator to determine your elevation at 25 and 50 yards to be dead on at 200.
http://www.hornady.com/ballistics/ballistics_calculator.php
You can probably guess at sight height (standard is 1.5") if the scope isn't anything really weird. The BC, you have to find out.
The Ballistic Coefficient is a number that indicates the effect of air resistance on the bullet as it flies, and it can vary quite a bit, even for a .308" 150 grain bullet.
If you have the weight, velocity, and the B.C., and the sight height above the bore, you can use this calculator to determine your elevation at 25 and 50 yards to be dead on at 200.
http://www.hornady.com/ballistics/ballistics_calculator.php
You can probably guess at sight height (standard is 1.5") if the scope isn't anything really weird. The BC, you have to find out.
The Ballistic Coefficient is a number that indicates the effect of air resistance on the bullet as it flies, and it can vary quite a bit, even for a .308" 150 grain bullet.
huntershooter
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By "going on a trip", do you mean a hunting trip, or a trip on which you plan to use your rifle?
If so, you are ill advised to try a 25 yd. sight in and then attempt to use the rifle at 200, 300, 400 yds.
I suppose you could be within "minute of moose", but I'd damn sure want to know what the rifle was actually going to do at the respective yardage.
Call it a "Murphy's Law" type of thing.
Good luck.
If so, you are ill advised to try a 25 yd. sight in and then attempt to use the rifle at 200, 300, 400 yds.
I suppose you could be within "minute of moose", but I'd damn sure want to know what the rifle was actually going to do at the respective yardage.
Call it a "Murphy's Law" type of thing.
Good luck.
KBintheSLC
Member
You need to know the caliber to get the b/c... you also need to know the bullet type spitzer/boat tail/HP/etc. You also need to know the exact height from the bore axis to the scope axis.
Other info that matters is elevation, temp, humidity, etc. Furthermore, every different bullet/load combo reacts differently to every rifle. If you can't test it at the range you plan on shooting at, it is little more than aimless theorizing that will likely yield different results.
Only so you can look up the BC. The calculation doesn't use the caliber. You need to know the EXACT BULLET you're using, not just if it's a boat tail or a flat base.
WRT sighting in at 50 and shooting at 200, it beats the hell out of not sighting in at all.
I have sighted in at 100 -- very precisely, with an accurate load, not just "within a couple inches" but truly dead-on -- then shot at 300 with no trouble. It hit right where I wanted it. Of course, I did try this out on targets, not game, first. But you can do that in the field, once the gun is sighted in precisely.
Humidity, etc. is nice and all, but unless you can sight in 5 seconds before you make the shot on game, you're going to have to go for "best efforts."
I'd sight it in at 50 yards, and be really anal about it, after doing the calculations. .300 Wby is a pretty flat shooter anyway.
Then, when you get to the field, put some small balloons at the maximum range where you think you'll take a shot. If you can pop 'em consistently, you can hunt with the rifle.
BADUNAME37
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I would venture to say the bullet is still traveling upward at 25 to 50 yards, so it may actually be crossing the straight line of sight on its way up a bit over the line of sight.
I bet if you shot a target right on at 25 and 50 yards, you would be pretty close to hitting dead-on center.
That is my "guestimation". Like was mentioned, the ballistic coefficient calculates the bullet's drag and you would need to chronograph your bullet to get the exact speed. I don't know if the speed you gave is an approximation or a chronied value.
Most reloading manuals have in them all the information you are requesting. I bet if you searched the web, you would find a site that would calculate all the exact distances and bullet drop at so many intervals.
I bet if you shot a target right on at 25 and 50 yards, you would be pretty close to hitting dead-on center.
That is my "guestimation". Like was mentioned, the ballistic coefficient calculates the bullet's drag and you would need to chronograph your bullet to get the exact speed. I don't know if the speed you gave is an approximation or a chronied value.
Most reloading manuals have in them all the information you are requesting. I bet if you searched the web, you would find a site that would calculate all the exact distances and bullet drop at so many intervals.
Last edited:
JimKirk
Member
Using a BC of .387 and velocity of 3375 FPS
Jimmy K
JBM - Calculations - Trajectory (Simplified)
Trajectory (Simplified)
Input Data
Ballistic Coefficient: 0.387 G1 Caliber: 0.308 in
Bullet Weight: 150.0 gr
Muzzle Velocity: 3375.0 ft/s
Sight Height: 1.50 in Line Of Sight Angle: 0.0 deg
Cant Angle: 0.0 deg
Wind Speed: 10.0 mph Target Speed: 10.0 mph
Temperature: 59.0 °F Pressure: 29.92 in Hg
Humidity: 0.0 % Altitude: 1000.0 ft
Std. Atmosphere at Altitude: Yes Pressure is Corrected: Yes
Zero at Max. Point Blank Range: No Target Relative Drops: Yes
Round Output to Whole Numbers: No
Output Data
Elevation: 3.972 MOA Windage: 0.000 MOA
Atmospheric Density: 0.07426 lb/ft³ Speed of Sound: 1112.6 ft/s
Maximum PBR: 393 yd Maximum PBR Zero: 335 yd
Range of Maximum Height: 186 yd Energy at Maximum PBR: 1956.8 ft•lbs
Sectional Density: 0.226 lb/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yd) (in) (MOA) (in) (MOA) (ft/s) (none) (ft•lbs) (s) (in) (MOA)
0 -1.5 *** 0.0 *** 3375.0 3.033 3793.2 0.000 0.0 ***
25 -0.6 -2.1 0.0 0.2 3307.7 2.973 3643.4 0.022 4.0 15.1
50 0.2 0.4 0.2 0.3 3241.5 2.913 3499.0 0.045 8.0 15.2
75 0.7 0.9 0.4 0.5 3176.3 2.855 3359.7 0.069 12.1 15.4
100 1.0 1.0 0.6 0.6 3112.1 2.797 3225.3 0.093 16.3 15.6
125 1.1 0.9 1.0 0.8 3048.9 2.740 3095.7 0.117 20.6 15.7
150 1.0 0.6 1.5 0.9 2986.7 2.684 2970.5 0.142 25.0 15.9
175 0.6 0.3 2.0 1.1 2925.3 2.629 2849.7 0.167 29.4 16.1
200 -0.0 -0.0 2.7 1.3 2864.8 2.575 2733.0 0.193 34.0 16.2
225 -0.9 -0.4 3.4 1.5 2805.1 2.521 2620.4 0.220 38.6 16.4
250 -2.1 -0.8 4.3 1.6 2746.3 2.468 2511.6 0.247 43.4 16.6
275 -3.5 -1.2 5.2 1.8 2688.2 2.416 2406.5 0.274 48.2 16.8
300 -5.3 -1.7 6.3 2.0 2630.9 2.365 2305.0 0.302 53.2 16.9
325 -7.4 -2.2 7.4 2.2 2574.4 2.314 2207.0 0.331 58.3 17.1
350 -9.8 -2.7 8.7 2.4 2518.5 2.264 2112.2 0.361 63.5 17.3
375 -12.5 -3.2 10.1 2.6 2463.3 2.214 2020.7 0.391 68.8 17.5
400 -15.6 -3.7 11.6 2.8 2408.9 2.165 1932.4 0.422 74.2 17.7
425 -19.1 -4.3 13.2 3.0 2355.1 2.117 1847.0 0.453 79.7 17.9
450 -23.0 -4.9 15.0 3.2 2302.0 2.069 1764.6 0.485 85.4 18.1
475 -27.3 -5.5 16.9 3.4 2249.5 2.022 1685.1 0.518 91.2 18.3
500 -32.0 -6.1 18.9 3.6 2197.7 1.975 1608.4 0.552 97.1 18.6
525 -37.1 -6.8 21.1 3.8 2146.6 1.929 1534.4 0.586 103.2 18.8
550 -42.7 -7.4 23.4 4.1 2096.1 1.884 1463.1 0.622 109.4 19.0
575 -48.9 -8.1 25.9 4.3 2046.3 1.839 1394.5 0.658 115.8 19.2
600 -55.5 -8.8 28.5 4.5 1997.2 1.795 1328.4 0.695 122.3 19.5
625 -62.7 -9.6 31.3 4.8 1948.9 1.752 1264.8 0.733 129.0 19.7
650 -70.5 -10.4 34.2 5.0 1901.2 1.709 1203.7 0.772 135.9 20.0
675 -78.8 -11.2 37.3 5.3 1854.4 1.667 1145.1 0.812 142.9 20.2
700 -87.8 -12.0 40.6 5.5 1808.2 1.625 1088.9 0.853 150.1 20.5
725 -97.5 -12.8 44.1 5.8 1762.9 1.584 1035.0 0.895 157.5 20.7
750 -107.8 -13.7 47.8 6.1 1718.5 1.545 983.4 0.938 165.1 21.0
775 -118.9 -14.7 51.6 6.4 1674.9 1.505 934.1 0.982 172.9 21.3
800 -130.8 -15.6 55.7 6.7 1632.2 1.467 887.1 1.028 180.9 21.6
825 -143.5 -16.6 60.0 6.9 1590.4 1.429 842.3 1.074 189.1 21.9
850 -157.0 -17.6 64.5 7.2 1549.6 1.393 799.7 1.122 197.5 22.2
875 -171.5 -18.7 69.2 7.6 1509.9 1.357 759.2 1.171 206.1 22.5
900 -186.9 -19.8 74.2 7.9 1471.2 1.322 720.8 1.221 215.0 22.8
925 -203.3 -21.0 79.3 8.2 1433.7 1.289 684.5 1.273 224.1 23.1
950 -220.7 -22.2 84.8 8.5 1397.3 1.256 650.2 1.326 233.4 23.5
975 -239.3 -23.4 90.4 8.9 1362.2 1.224 617.9 1.380 243.0 23.8
1000 -259.0 -24.7 96.3 9.2 1328.4 1.194 587.6 1.436 252.8 24.1
As you can see ...you will need to be -0.6 @ 25 yds and + 0.2 @ 50 Yds
IF you are using a bullet that matches these numbers BC & Velocity.
http://www.jbmballistics.com/calculations/calculations.html
Jimmy K
JBM - Calculations - Trajectory (Simplified)
Trajectory (Simplified)
Input Data
Ballistic Coefficient: 0.387 G1 Caliber: 0.308 in
Bullet Weight: 150.0 gr
Muzzle Velocity: 3375.0 ft/s
Sight Height: 1.50 in Line Of Sight Angle: 0.0 deg
Cant Angle: 0.0 deg
Wind Speed: 10.0 mph Target Speed: 10.0 mph
Temperature: 59.0 °F Pressure: 29.92 in Hg
Humidity: 0.0 % Altitude: 1000.0 ft
Std. Atmosphere at Altitude: Yes Pressure is Corrected: Yes
Zero at Max. Point Blank Range: No Target Relative Drops: Yes
Round Output to Whole Numbers: No
Output Data
Elevation: 3.972 MOA Windage: 0.000 MOA
Atmospheric Density: 0.07426 lb/ft³ Speed of Sound: 1112.6 ft/s
Maximum PBR: 393 yd Maximum PBR Zero: 335 yd
Range of Maximum Height: 186 yd Energy at Maximum PBR: 1956.8 ft•lbs
Sectional Density: 0.226 lb/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yd) (in) (MOA) (in) (MOA) (ft/s) (none) (ft•lbs) (s) (in) (MOA)
0 -1.5 *** 0.0 *** 3375.0 3.033 3793.2 0.000 0.0 ***
25 -0.6 -2.1 0.0 0.2 3307.7 2.973 3643.4 0.022 4.0 15.1
50 0.2 0.4 0.2 0.3 3241.5 2.913 3499.0 0.045 8.0 15.2
75 0.7 0.9 0.4 0.5 3176.3 2.855 3359.7 0.069 12.1 15.4
100 1.0 1.0 0.6 0.6 3112.1 2.797 3225.3 0.093 16.3 15.6
125 1.1 0.9 1.0 0.8 3048.9 2.740 3095.7 0.117 20.6 15.7
150 1.0 0.6 1.5 0.9 2986.7 2.684 2970.5 0.142 25.0 15.9
175 0.6 0.3 2.0 1.1 2925.3 2.629 2849.7 0.167 29.4 16.1
200 -0.0 -0.0 2.7 1.3 2864.8 2.575 2733.0 0.193 34.0 16.2
225 -0.9 -0.4 3.4 1.5 2805.1 2.521 2620.4 0.220 38.6 16.4
250 -2.1 -0.8 4.3 1.6 2746.3 2.468 2511.6 0.247 43.4 16.6
275 -3.5 -1.2 5.2 1.8 2688.2 2.416 2406.5 0.274 48.2 16.8
300 -5.3 -1.7 6.3 2.0 2630.9 2.365 2305.0 0.302 53.2 16.9
325 -7.4 -2.2 7.4 2.2 2574.4 2.314 2207.0 0.331 58.3 17.1
350 -9.8 -2.7 8.7 2.4 2518.5 2.264 2112.2 0.361 63.5 17.3
375 -12.5 -3.2 10.1 2.6 2463.3 2.214 2020.7 0.391 68.8 17.5
400 -15.6 -3.7 11.6 2.8 2408.9 2.165 1932.4 0.422 74.2 17.7
425 -19.1 -4.3 13.2 3.0 2355.1 2.117 1847.0 0.453 79.7 17.9
450 -23.0 -4.9 15.0 3.2 2302.0 2.069 1764.6 0.485 85.4 18.1
475 -27.3 -5.5 16.9 3.4 2249.5 2.022 1685.1 0.518 91.2 18.3
500 -32.0 -6.1 18.9 3.6 2197.7 1.975 1608.4 0.552 97.1 18.6
525 -37.1 -6.8 21.1 3.8 2146.6 1.929 1534.4 0.586 103.2 18.8
550 -42.7 -7.4 23.4 4.1 2096.1 1.884 1463.1 0.622 109.4 19.0
575 -48.9 -8.1 25.9 4.3 2046.3 1.839 1394.5 0.658 115.8 19.2
600 -55.5 -8.8 28.5 4.5 1997.2 1.795 1328.4 0.695 122.3 19.5
625 -62.7 -9.6 31.3 4.8 1948.9 1.752 1264.8 0.733 129.0 19.7
650 -70.5 -10.4 34.2 5.0 1901.2 1.709 1203.7 0.772 135.9 20.0
675 -78.8 -11.2 37.3 5.3 1854.4 1.667 1145.1 0.812 142.9 20.2
700 -87.8 -12.0 40.6 5.5 1808.2 1.625 1088.9 0.853 150.1 20.5
725 -97.5 -12.8 44.1 5.8 1762.9 1.584 1035.0 0.895 157.5 20.7
750 -107.8 -13.7 47.8 6.1 1718.5 1.545 983.4 0.938 165.1 21.0
775 -118.9 -14.7 51.6 6.4 1674.9 1.505 934.1 0.982 172.9 21.3
800 -130.8 -15.6 55.7 6.7 1632.2 1.467 887.1 1.028 180.9 21.6
825 -143.5 -16.6 60.0 6.9 1590.4 1.429 842.3 1.074 189.1 21.9
850 -157.0 -17.6 64.5 7.2 1549.6 1.393 799.7 1.122 197.5 22.2
875 -171.5 -18.7 69.2 7.6 1509.9 1.357 759.2 1.171 206.1 22.5
900 -186.9 -19.8 74.2 7.9 1471.2 1.322 720.8 1.221 215.0 22.8
925 -203.3 -21.0 79.3 8.2 1433.7 1.289 684.5 1.273 224.1 23.1
950 -220.7 -22.2 84.8 8.5 1397.3 1.256 650.2 1.326 233.4 23.5
975 -239.3 -23.4 90.4 8.9 1362.2 1.224 617.9 1.380 243.0 23.8
1000 -259.0 -24.7 96.3 9.2 1328.4 1.194 587.6 1.436 252.8 24.1
As you can see ...you will need to be -0.6 @ 25 yds and + 0.2 @ 50 Yds
IF you are using a bullet that matches these numbers BC & Velocity.
http://www.jbmballistics.com/calculations/calculations.html
Last edited:
BADUNAME37
Member
- Joined
- Aug 10, 2008
- Messages
- 4,434
Correct, and we are assuming that a chronograph has been used and a mean velocity calculated over say five or ten rounds.
Otherwise, those figures really mean nothing as I found out AFTER I purchased my CHRONOGRAPH and realized how many hundreds of feet-per-second I was off at ESTIMATING as it changed what I thought my gun was doing for over twenty years! My gun was shooting at 3,990 FPS instead of 3,700 FPS.
JimKirk
Member
Just using what was provided! This is why if you are asking for help please supply all the information that you have. Any info provided with out measurement is suspect at best. This is why I own a chronograph. Do I wish I could own the million of dollars of equipment that a ballistic lab has .... you bet...... would it make me a better shot....NO...but I would like to try it!
Sorry about the column alignment on the chart, if I could only get my screenshots to work.
Jimmy K
Sorry about the column alignment on the chart, if I could only get my screenshots to work.
Jimmy K
JimKirk
Member
Ace,
I went back and reread all the post, I like others here skim over posts sometimes, jumping to conclusions without reading the details. I really don't think anyone was being a smartaxx, just asking for details. Without the details we can only give generalization's. By the way Inspector, I qualified the results with the statement that "IF you are using a bullet that matches these numbers BC & Velocity".
Jimmy K
I went back and reread all the post, I like others here skim over posts sometimes, jumping to conclusions without reading the details. I really don't think anyone was being a smartaxx, just asking for details. Without the details we can only give generalization's. By the way Inspector, I qualified the results with the statement that "IF you are using a bullet that matches these numbers BC & Velocity".
Jimmy K
hopefully when you get to your destination you can shoot at some realistic hunting distances you'd be attempting to shoot at, like armed bear mentions. Sighting in at 25 yards and attemting to shoot a game animal at 400 would be unethical. Heck even if you have shot at 400 at the range, there are enough variables under field conditions to make it less than a sure thing.
You might want to be a little more gracious when people are trying to help you. I was checking back to see if this got answered & I see you have a bad attitude about my question.
I was asking for the caliber & height over bore of the sights as that would allow someone to help you more quickly and more precisely.
I have had people here help with the exact same problem as you. The more exact the info you provide up front the easier it makes it for some stranger to help you.
I wouldn't hunt with a non-verified zero and drops. Not being a smarty pants either.
I was asking for the caliber & height over bore of the sights as that would allow someone to help you more quickly and more precisely.
I have had people here help with the exact same problem as you. The more exact the info you provide up front the easier it makes it for some stranger to help you.
I wouldn't hunt with a non-verified zero and drops. Not being a smarty pants either.
Zak Smith
Member
Some good information, some bad information, too much attitude.
Using a 25 or 50-yard zero to set a primary 100-yard zero can work, and work pretty well. The most important two parameters to do this are: sight center over bore center distance and the muzzle velocity. BC is important also, but a 25% difference in BC (0.3 to 0.4) only imparts about 0.02 MOA error at 100, while a 150 fps difference in MV (3000 vs 3150) would impart about 0.1 MOA error. On the other hand, a 1.5 vs 2.5 SOB measurement error would cause almost 0.9 MOA error at 100. All these examples were from sighting in at 50 to get a 100 zero.
Using a 25 or 50-yard zero to set a primary 100-yard zero can work, and work pretty well. The most important two parameters to do this are: sight center over bore center distance and the muzzle velocity. BC is important also, but a 25% difference in BC (0.3 to 0.4) only imparts about 0.02 MOA error at 100, while a 150 fps difference in MV (3000 vs 3150) would impart about 0.1 MOA error. On the other hand, a 1.5 vs 2.5 SOB measurement error would cause almost 0.9 MOA error at 100. All these examples were from sighting in at 50 to get a 100 zero.
KBintheSLC
Member
You guys have a good point. I think that if you get all of your variables as close as possible, your ballistic calculator can get you within an inch or two despite variances in your ammo/rifle combo. I would bet that 2" off at 200 yards won't be that bad on big game.
I use a calculator to estimate POI at ranges that my target range does not offer. They offer 25, 50, 100, 200, 300, 400, 500, 600 yards. But what if I want to hit something small at 256 yards? That is where the calculator comes in very handy. Just try to get your variables as close as possible and you should be fine.
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