one would assume that you would just enter in the figures in the new fancy free ballistic programs and you could be right on that coyote or deer at 274 yards after taking a reading with the range finder and setting the sites to the chart.. more likely the 500 yard steel critter at the new townsend gun club range.. which doesnt seem to have any hope of getting finished soon..
Well it just doesnt seem to be that easy to get the charts on track.. ive always had a belly in the middle and all kinds of fudgeing including extra feet per second to get it close.. i keep whitteling at it and one problem is air density has to be artificially lowered on the program i use for some reason becouse here in montana i dont think our air density is 99 percent of sea level, which is what the program wants to enter...
the next probem i started working on last night is sight radius.. my gun is 34 inches and correcting for 1000 yards the tables are not bad for my velocity at 940 yards which corresponds to the .944 percent difference in my gun sight spread . there is a minute or so off at 400 yards. ( i would use 400 x .944= 374 yards for acturall drop reading for 400 yards).. which means the other middle distances are off also, but with some more testing and tweeking all this will get me alot closer to estimating unverified distances.. . obvously ill have to do a better job of finding the 1000 yards settings as seen in my last post tho. it looks like ill need a sepparate chart for each 10 degrees weather change....
before anyone gets all excited about the logistics of this i just do this for something to do on a day off.. im 56 and dont jog.... the silloetss seem to be too far away in butte, i was going to go down and try it but the last time i was comming back from butte the hail broke a headlight, and i thought it was going to take my windshild out,.. the hail was so deep on the road i had to have matt my son get out in it and see if we had a flat as we ground down thru 1 1/2 inches of hail on the highway.. not a fun trip... maybe ill get brave later this summer and go on down for a first shoot at the steel critters... but id at least like a fighting chance at knowing the range settings with a good set of charts.. dave..
getting alot closer to haveing ballistic tables match sights
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ffffgdave@yahoo.com
- Posts: 283
- Joined: Wed Feb 19, 2003 9:05 pm
- Location: helena montana
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RMulhern
- Posts: 7682
- Joined: Thu Nov 28, 2002 9:41 pm
- Location: North Louisiana
ballistic tables
Forget the programs/tables/etc.! Go shoot your rifle at various ranges to be used....record the zeros in a data book.....and you'll be OK...eventually! 
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Dang Long Shot
- Posts: 314
- Joined: Tue Apr 19, 2005 1:18 pm
- Location: Lakeland, Florida
fffgdave,
i saw your post and can relate. After much reading, and using the ballistic charts I finally got really close using some information in a book from Paul mathews. My confirmed site settings vs the following info I will give you seems to be within one minute of angle or so.
First measure your actual distance from front site to your Vernier eye piece and write it down. Say you have a confirmed site setting at 100 yds of say .22 pts use that as your base line parameter. there is 3,600 inches in a 100 yds. divide your actual site radius by number of inches. Lets asume that your site radius is 35" inches.(30" Barrel)
Example: 200 yds = 7,200 inches so 35 divided by 7,200= .00486. That how much of a site adjustment that is necessary for a movement of 1" of your bullet at that distance. Now just look at the actual bullet drop in inches off your ballaistic program and multiply .00486 X 25.92" drop= .126 of correction to add to your 100 yd setting or .346 pts for that 200 yard setting.
All this is a factor of initial muzzle velocity and the bullets coficient which you plug into your ballistics program. So far with this method, I've been darn close with both of my rifles, one is a 30" Hartford the other is a 32: barreled Quigley. And yes it can vary a point or two and as the barrel or site radius goes up the amount of site setting increases as well. All this sounds more complicated than it really is. Try it out, do alittle math and see if the numbers reflec your range site data.
Hope this helps you out.
Denis
i saw your post and can relate. After much reading, and using the ballistic charts I finally got really close using some information in a book from Paul mathews. My confirmed site settings vs the following info I will give you seems to be within one minute of angle or so.
First measure your actual distance from front site to your Vernier eye piece and write it down. Say you have a confirmed site setting at 100 yds of say .22 pts use that as your base line parameter. there is 3,600 inches in a 100 yds. divide your actual site radius by number of inches. Lets asume that your site radius is 35" inches.(30" Barrel)
Example: 200 yds = 7,200 inches so 35 divided by 7,200= .00486. That how much of a site adjustment that is necessary for a movement of 1" of your bullet at that distance. Now just look at the actual bullet drop in inches off your ballaistic program and multiply .00486 X 25.92" drop= .126 of correction to add to your 100 yd setting or .346 pts for that 200 yard setting.
All this is a factor of initial muzzle velocity and the bullets coficient which you plug into your ballistics program. So far with this method, I've been darn close with both of my rifles, one is a 30" Hartford the other is a 32: barreled Quigley. And yes it can vary a point or two and as the barrel or site radius goes up the amount of site setting increases as well. All this sounds more complicated than it really is. Try it out, do alittle math and see if the numbers reflec your range site data.
Hope this helps you out.
Denis
Dang Long Shot
Speak Softly & Carry a Big Sharps. They will see the flash but they won't hear the bang.
Shiloh Hartford Model 30" Heavy 45-70
Shiloh Montana Rough Rider 34" Hvy 45-70 semi fancy wood, pewter tip
NRA, SASS
Florida Frontiersman
Speak Softly & Carry a Big Sharps. They will see the flash but they won't hear the bang.
Shiloh Hartford Model 30" Heavy 45-70
Shiloh Montana Rough Rider 34" Hvy 45-70 semi fancy wood, pewter tip
NRA, SASS
Florida Frontiersman
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Clarence
- Posts: 2172
- Joined: Tue Dec 24, 2002 7:38 pm
- Location: Hill Country, TX
Just a reminder-you will see considerable variation between cold and hot weather. Either Rywell or Sellers gives a number from an original Sharps catalog. I didn't look, but my recollection is that Sharps indicated a variation of up to 10 MOA at 1000 yds.
Your ballistic coefficient also changes as you change elevations. The elevation change from sea level on the Gulf Coast to Raton changes by ~3 MOA for me. My guess is that you are somewhere around 4000-4300 ft. elevation between Helena and Townsend (I grew up around Bozeman). Because of the air density change, you can expect your actual ballistic coefficient to be as much as 10-12% higher than sea level values. (That's what makes the change between cold and hot weather, as well-the air is more dense at colder temperatures, lowering the ballistic coefficient.)
The message is: don't look for the level of precision in a ballistic table that you would expect with a modern 300 whiz-bang. These bullets are in the air for almost three times as long, making these changes much more apparent. Isn't that why we love these things?
Clarence
Your ballistic coefficient also changes as you change elevations. The elevation change from sea level on the Gulf Coast to Raton changes by ~3 MOA for me. My guess is that you are somewhere around 4000-4300 ft. elevation between Helena and Townsend (I grew up around Bozeman). Because of the air density change, you can expect your actual ballistic coefficient to be as much as 10-12% higher than sea level values. (That's what makes the change between cold and hot weather, as well-the air is more dense at colder temperatures, lowering the ballistic coefficient.)
The message is: don't look for the level of precision in a ballistic table that you would expect with a modern 300 whiz-bang. These bullets are in the air for almost three times as long, making these changes much more apparent. Isn't that why we love these things?
Clarence
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Clarence
- Posts: 2172
- Joined: Tue Dec 24, 2002 7:38 pm
- Location: Hill Country, TX
Just a reminder-you will see considerable variation between cold and hot weather. Either Rywell or Sellers gives a number from an original Sharps catalog. I didn't look, but my recollection is that Sharps indicated a variation of up to 10 MOA at 1000 yds.
Your ballistic coefficient also changes as you change elevations. The elevation change from sea level on the Gulf Coast to Raton changes by ~3 MOA for me. My guess is that you are somewhere around 4000-4300 ft. elevation between Helena and Townsend (I grew up around Bozeman). Because of the air density change, you can expect your actual ballistic coefficient to be as much as 10-12% higher than sea level values. (That's what makes the change between cold and hot weather, as well-the air is more dense at colder temperatures, lowering the ballistic coefficient.)
The message is: don't look for the level of precision in a ballistic table that you would expect with a modern 300 whiz-bang. These bullets are in the air for almost three times as long, making these changes much more apparent. Isn't that why we love these things?
Clarence
Your ballistic coefficient also changes as you change elevations. The elevation change from sea level on the Gulf Coast to Raton changes by ~3 MOA for me. My guess is that you are somewhere around 4000-4300 ft. elevation between Helena and Townsend (I grew up around Bozeman). Because of the air density change, you can expect your actual ballistic coefficient to be as much as 10-12% higher than sea level values. (That's what makes the change between cold and hot weather, as well-the air is more dense at colder temperatures, lowering the ballistic coefficient.)
The message is: don't look for the level of precision in a ballistic table that you would expect with a modern 300 whiz-bang. These bullets are in the air for almost three times as long, making these changes much more apparent. Isn't that why we love these things?
Clarence
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dakotasharps
- Posts: 116
- Joined: Sat Aug 27, 2005 11:48 pm
- Location: Spearfish SD
I am new to this site (which is by the way excellent). I am also relatively new to BP cartridge shooting having owned an 1859 Sharps for a few years and having recently acquired a Pedersoli 1874 in 45-70 and am in the process of adapting national match/high power experience to something far more challenging. So this is probably old hat to most on the board, but may be helpful to newer shooters.
Temperature and barometric pressure/altitude both affect air density and in turn the effective ballistic coefficient.
With a modern high velocity cartridge and bullet with a high ballistic coefficient (in the .600 range) these variables do not make nearly as much difference as they do in a BP cartridge. For example you may only need to add 10-12 minutes of angle of elevation at 500 yds as opposed to maybe 4 to 5 times that correction needed for the slow and less efficient bullet you are shooting at the same range. In this case, the minor details begin to make a major difference - which frankly is a big part of the appeal for me of shooting a black powder cartridge at long range.
Ballistics programs can be very capable of figuring trajectory but are only as good as the data you are putting into the program. Tables are even more problematic, as you are stuck with the default conditions used by the tables.
So knowing all of your variables as precisely as possible (muzzle velocity, BC, temp, etc) is required to get good data from a program. Velocity is relatively easy to measure with a chronograph, although you need to be aware of the effect the temperature of the round has on velocity. The effect of temp on interior and exterior balistics will coincide here as on a hot day you will have less density, a higher effective BC and a round that is leaving the barrel with higher than normal velocity due to its higher temperature.
Consequently if you take your observed results on a range on a hot day in August and try to apply them on a cold day in the field in November, your bullet is going to drop a lot more than you expect.
So far I have found that an accurate BC is often hard to find for a given cast bullet and that good field notes and a data book often help you reverse engineer a BC for a particular bullet using a ballistic program to produce a trajectory that matches your observed results.
If you start religeously keeping a data book, over time you will see the patterns emerge (with or without a ballistics program) and will be able to do a much better job of anticipating the elevation and windage required and will have a higher probability of getting the first shot on target. In my limited BP experience, this has proven to also be about 5 times as important as it is with a modern high velocity round.
Temperature and barometric pressure/altitude both affect air density and in turn the effective ballistic coefficient.
With a modern high velocity cartridge and bullet with a high ballistic coefficient (in the .600 range) these variables do not make nearly as much difference as they do in a BP cartridge. For example you may only need to add 10-12 minutes of angle of elevation at 500 yds as opposed to maybe 4 to 5 times that correction needed for the slow and less efficient bullet you are shooting at the same range. In this case, the minor details begin to make a major difference - which frankly is a big part of the appeal for me of shooting a black powder cartridge at long range.
Ballistics programs can be very capable of figuring trajectory but are only as good as the data you are putting into the program. Tables are even more problematic, as you are stuck with the default conditions used by the tables.
So knowing all of your variables as precisely as possible (muzzle velocity, BC, temp, etc) is required to get good data from a program. Velocity is relatively easy to measure with a chronograph, although you need to be aware of the effect the temperature of the round has on velocity. The effect of temp on interior and exterior balistics will coincide here as on a hot day you will have less density, a higher effective BC and a round that is leaving the barrel with higher than normal velocity due to its higher temperature.
Consequently if you take your observed results on a range on a hot day in August and try to apply them on a cold day in the field in November, your bullet is going to drop a lot more than you expect.
So far I have found that an accurate BC is often hard to find for a given cast bullet and that good field notes and a data book often help you reverse engineer a BC for a particular bullet using a ballistic program to produce a trajectory that matches your observed results.
If you start religeously keeping a data book, over time you will see the patterns emerge (with or without a ballistics program) and will be able to do a much better job of anticipating the elevation and windage required and will have a higher probability of getting the first shot on target. In my limited BP experience, this has proven to also be about 5 times as important as it is with a modern high velocity round.
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ffffgdave@yahoo.com
- Posts: 283
- Joined: Wed Feb 19, 2003 9:05 pm
- Location: helena montana
a good computer ballistic program takes into account, elevation, temp, crosswind, humidity and other factors.. see http://www.beartoothbullets.com/ ........... for example.. if i enter data correctly im getting at the range, which makes the points inbetween, (that the range finder puts that pesky yote at), available to a 500 grain postel... the beartooth program will print out a balistic program for every 5 yards out to 400 yards or 1000 yards if i ask it to.. im actually after elk, so i dont have to be so darn picky, but its nice to know the settings for 365 yards or 462 yards, when ive never shot at that distance, and records wont do it if i havent shot it before.. .. my opinon only.. yes you do have to account for temperature, even my flintlock shotgun has loads for every 10 degrees from 70 above to 20 below that will kill a duck within a reasonable range at those temperatures... those ballistic charts were made 15 years ago for that gun, ... i came into 45-70 bp shooting from shooting muzzeloader competition in shotgun and rifle again 15 years ago. the biggest problem i had was manageing recoil with the slow barrel time and heavy bullets, when i got ahold of that at the bench it was much easier and then somewhat similar to muzzeloading problems with black powder.... dave
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RMulhern
- Posts: 7682
- Joined: Thu Nov 28, 2002 9:41 pm
- Location: North Louisiana
Ballistic charts
As a member of the F.E.S. I'm glad you've got a lot of faith in them thar tables but I for one know that the ONLY WAY you're gonna find out what your rifle/bullet are doing is to shoot at the various ranges under varying temp conditions/elevations and record where the shots are going!
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ffffgdave@yahoo.com
- Posts: 283
- Joined: Wed Feb 19, 2003 9:05 pm
- Location: helena montana
i agree the tables are are guidline, but dont we also have to adjust our tables each time out also for the impercivebale conditions that we encounter when shooting target? so hard made actual tables are not totally correct either?.. when are we going to have the time to record every 10 yards out to 400 yards at every 10 degrees from 90 above to 20 below??? if the tables match at 100, 200, 300 and 400, thats good enough for hunting, and availible . for target we sight in for the range and the days conditions anyway.. dave.