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Old April 18, 2013, 01:55 PM   #1
savagest
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1000 yard Ballistic chart for .308 175g FGMM

I was wondering if anyone has a ballistic chart for this round. I have found some online but they only go out to 500 yards even though some say they go out to 1000 yards.

Here is the specs .308, 175 grain HPBT, 2600fps muzzle and I don't remember the BC right now but I will try to find it. I am also shooting through a 20" barrel so 2550fps would be nice too. Thanks in advance.
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Old April 18, 2013, 02:00 PM   #2
Brian Pfleuger
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JBM Ballistics will take you as far as you want to go.

http://www.jbmballistics.com/ballist...culators.shtml
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Old April 18, 2013, 02:28 PM   #3
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If you have an iPhone or Android phone you could also download a ballistic calculator. I recommend a program called Strelok, I know that for android there are several versions that cost $0-8. I would pay $8 for the free version. Strelok+ is $5. It even has reticules to give you a visual idea of holdover, if your scope reticule is not available you can email the program creator and it will likely be included in the next update, sometimes in as little as a day.

Top notch, loaded with useful features. 237 reviews with 4.8/5 stars for Strelok+. The free version has 2,467 reviews at the moment with 4.7/5 stars.
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Old April 18, 2013, 03:48 PM   #4
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Old April 19, 2013, 11:50 AM   #5
alex0535
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^Who zero's their rifle at 1000 yards? (unless you have a rifle dedicated for 1000 yard shots)

At first i found it odd that drop at 100 yards is 44 inches. Then I looked at the zero range.

Last edited by alex0535; April 21, 2013 at 08:28 PM.
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Old April 19, 2013, 03:49 PM   #6
Bart B.
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I agree Alex, that first "Drop (in)" column should be headed "Bullet Path)" with + before those above the line of sight and - for those below it.
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Old April 19, 2013, 04:48 PM   #7
kraigwy
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Quote:
^Who zero's their rifle at 1000 yards
I do.

I have a Model 70 in 300 WM that I built especially for 1000 yard matches.

Why would I zero a dedicated 1000 yard rifle anywhere but 1000 yards.
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Old April 21, 2013, 06:15 PM   #8
Tempest 455
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As above, my rilfe is now zeroed at 1,000 yards. It was zeroed at 400 but my son got the F class bug and we just leave it zeroed at 1,000.

Mine is a Savage .308 and we shoot SMK 175g.
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Old April 22, 2013, 02:37 AM   #9
savagest
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cool, I have mine zeroed at 100 yards, I like to mess with the mil dots and scope tracing. makes it fun for me. Would anyone mind putting up a chart for me with a 100 yard zero.
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Old April 22, 2013, 05:19 AM   #10
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Ballistic Progams are fun to play with but they won't be on the money unless it is confirmed. Per the guys at the Ballistic Research Lab at Aberdeen Proving Ground down range performance duplicates computer projections 5% of the time


John Unertl had the contract for the first USMC Sniper Scope back in late 70s and he asked me if I could get him a "good ballistic program for M118 Match". He went on to say that he had been provided five ballistic programs and that he had made elevation mechanisms for all five programs. He also said, "none of the programs matched and none of them were the same".


In those days I was working for the Army Small Cal Lab at Picatinny and had been sent to Perry as the Tech Rep for the lab as I was the only active smallbore and highpower shooter at the lab. Thusly when John told me he had data from multiple places and none was correct I was intrigued. When I returned to the lab I immediately went to see the Chief who previously had been at Frankford Arsenal and told him John Unertl's problem and he sent me to Bob Udell who was Chief of Ammo Branch and had spent his entire career in ammunition production. Bob told me to come back the following day as he had a conference that day he was leaving for shortly and another in the morning and to come back right after lunch and he would dig it out for me.
The following day I walked into his area and he saw me coming and headed for his office and retrieved a thick manila envelope and said,”Here it is and there are two additional ones for + and – 50FPS for hot and cold.” On the way back to my area I stopped by the copy office and ran myself a copy I still have somewhere. I was digging through stuff about five years back and ran across it.


I dropped it in the mail to John and heard nothing from it and the following year I went to John’s “shop” on Commercial Row and asked him if it was good and he said, “Absolutely perfect at all ranges.” In those days I was a shooter but had just got into the weapons field and I had no idea of what went into ammo testing and weapons testing.


A couple years later I was offered a job at Aberdeen as Small Arms and Ammunition Test Director when I was sent down to pick up “dust” for a test we were going to run at Picatinny and I took it and thusly my area of small arms knowledge was enhanced even further. It is extremely rare to find someone that has worked both ends (product engineering, development and test and evaluation) and I only know one other still alive. There was a third named W.C. “Bill” Davis and you can see him on the History Channel being interviewed about the M16. He is the guy with the white hair flat top hair cut and he was considered the “Dean of gov’t small arms program” and he was THE authority that was hired by the industry to figure out answers to problems the industry could not. His firm was known as Tioga Engineering in PA.


After arriving at Aberdeen I had a trajectory question and was directed to a guy in the Ballistic Research Lab whose entire career had been in that field and he is the one that told me the “5%” figure and went on to say that computer projections might be right on at two ranges, say 300 and 700 yards but off everywhere else. That floored me but within 18 months I found out exactly why the M118 data was spot on and how it was developed.
I ran the testing to develope the range tables for the M855 round fired from the new 7” twist heavy barrels and the following was how it was done.
All the M16A1E1 candidates were tested for dispersion at 100 yards and the three rifles were selected.


This was the best shooting rifle, a second rifle from the middle of the acceptance range and the worst shooting rifle that met acceptance standards which was 4.5” or less at 100 yards.


Each rifle is also subjected to chronograph records and the velocity differences are recorded for each rifle as the same lot of ammunition is used for all firing.


Next the rifles were zeroed to hit point of aim at 100 meters referred to as POA/POI (point of aim/ point of impact). Once this was accomplished the sights were never touched again as the range increased.


The requirement was for two NRA Master Class shooters to conduct this series but I was the only one on the Proving Ground thusly the Marine Corps had to send Master shooters up on two week TDY status to be the other shooter and a total of three came up. The data crunchers said they could work the numbers as long as there was one shooter that fired all the series and which they would call the control shooter.


The problem with rotating shooters is even though all may be Master Class shooters it is rare for two shooters to have the same point of impact utilizing the same zero and this became apparent as the ranges increased as the rifles are “held” differently and the point of aim is different due to difference in visual ability. A “line of white” is different for different shooters when using post sights thusly the data would be affected unless there is a control factor.
The series is fired as such. Each shooter would fire each of the three rifles three ten shot groups with each rifle (good, mediocre and worst shooting). After each 3 runs of ten rounds we went down and the fun started. From the aiming point we had to measure the distance from a horizontal line and a vertical line that to the middle of each shot hole with a certified calibration meter tape tape down to the closest MM to the center of the shot hole. The location was entered on a data sheet for each rifle and each shooter and sent to a computer center where the data is entered. The computer program (I would love to have this program in my computer) would calculate the extreme spread, the extreme height, width and the mathematical center of all thirty shots and poop out a target indicating all shots and a little triangle figures for group centers for each rifle and each shooter. It had the average of each and for all three rifles and the average of all three rifles for each range increment.

That took about three months to shoot as we could only fire on the days of wind less than 10 MPH so there were times when we were “down” for one to maybe three days” and if we were firing and the wind got up we got a call from the weather boys to advise us and we shut down.


This testing was duplicated at 200, 300,400, 500, 600, 700 and 800 meters. OK if the sights are not allowed to be adjusted how is this done? We had a target that was 32 feet tall and 32 feet wide and we covered the entire board with target cloth. Every time I see a drive in movie screen I think of this testing. When the range increased and the drops got near the bottom we raised the target thusly by the time we finished at 800 meters the aim point was approximately 26 feet from the bottom of the target.


To get the measurements a gun crew member was in a cherry picker bucket holding the tape at the aim point. At the longer ranges this required two bucket trucks. One to hold the tape on the line and the other to read the MMs and a third to record the reading on the data sheet.


The data was very interesting to see the differences of each rifle and each shooter and the averages at each range increment.


Bottom line here is if you want “spot on” values you are going to have to construct your own target and shoot each yard line all the way to 1000 and measure the drops of all shots and determine your average.(Better make your target about 36 feet tall for heavier bullets).


I have a 900 yard range and for all practical purposes for hunting rifles I have a 4X8 foot target that I have will take me to 500-700 yards depending on the caliber/velocity etc. I get a quick and dirty setting by firing 3 shots at each yard line then I measure all shots and get the average drop for each yard line for that barrel and load. If you do the full 30 shots series you are going to have about 400 rounds on your barrel to get the data.


Oh by the way you need to chronograph as well about every 100 shots to see how your average is holding up as when barrels start to wear you will get a change in average velocity especially if you have a barrel burner like a 6.5X284 or a magnum etc. My way of three shots at each yard line will not be nearly as accurate for group center but you will have much more useable barrel life left in your barrel.


If you run 400 rounds on your magnum your barrel is about at the end of its useful life and if you think you can just use that data on your next barrel, chances are very high the data won’t duplicate as barrel internal dimensions won’t duplicate and you are back to square one.


Occasionally you get a guy at Camp Perry and you see them with a green/white line computer data sheet all laid out and calculating the drift after taking the wind speed etc etc etc and they lay down and shoot. I watched this one guy do all his meticulous gyrations and he laid down, the targets came up at 1000 yards and he fired five shots and never made paper, got up, packed up and walked off the line.

There is a saying that fits nicely here: “Just when you think you have all the answers they change all the questions.”
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Old April 22, 2013, 07:15 AM   #11
Tempest 455
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Agree with some of the comments above. JBM for example is great but crap in, crap out. The more accurate data you plug in the better results you will get.

I've went from a 100 yard zero on a .223 out to 400 yards in the X in 2 shots using JBM. The data must have been on. On the other end of the spectrum, I went from a 400 yard zero with a .308 to 1,000 and burned up some ammo getting on target. The drop was fine but the wind is much harder to account for. It will get you close but after that, you need to read the wind.
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Old April 22, 2013, 04:36 PM   #12
RamItOne
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Quote:
Originally Posted by Alex0535
^Who zero's their rifle at 1000 yards?
Quote:
Originally Posted by kraigwy
I do
Well thats all I need to hear to know I wasn't crazy.





savagest here is one w/ a 100 yard zero


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Old April 22, 2013, 05:40 PM   #13
Bart B.
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I have used Sierra Bullets' old software to calculate sight settings based on a zero at 100 yards and the come ups for 600, 800 and 1000 yards. Muzzle velocity was know from chronograph data and the atmospheric conditions noted for both when zeros were established as well as when chronographing. Done this for 190's and 155's in a .308 Win. case in each of two different rifles.

Zeros were established for "mechanical zeros" meaning the sights would be set to match a "shooting boresight" for an target at infinity. Shooting prone a 100 yards, the sight settings for a zero were logged then calculated bullet drop and front sight aperture height above bore center were subtracted and the rear sight lowered such to move the group center down that far. Actual sight radius and thread counts on the sight lead screws were known to use in the calculations. The resulting sight setting was the "mechancal zero" and was the reference for sight settings at the longer ranges.

Using Sierra's software and the atmospheric conditions at the range, come ups were calculated for each bullet and rifle combination. At all three ranges, the actual sight settings for a zero at them was within 1/4 MOA of what was calculated. Sierra's software, in my opinion, was right on the money.
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Old April 22, 2013, 11:36 PM   #14
savagest
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thank you guys so much. I am going camping tomorrow where i can stretch the legs out on my savage model 10. I'll post back with results.
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