hunting conditions? perfect weather eh. no wind at all. the shots were done prone from a rest. didnt use a bi-pod because the difference in the hardness and softness in ground affects it. range was found using a range finder, unsure of what brand but it was either leica or swarovski. and it is a specialist rifle which he used for F class benchrest, and did very well.

/

haha yeah a 1000 yard bench range. nearly but not quite :P was out in the sticks but its all the same really. he seemed to think it did about an inch at 300yards off the bench.

/

might have been a bit of luck in it too id say, but the goats were just standing around! didnt even want to move, as i said before it was perfectly calm where we were. and those range finders, well leica ones are within 0.5% which is 5 inch at 1000yards.

I know the higher BC the less the bullet will drop. With the BCs I always check at 600yds to see witch BC drops more.

0.5% of 1000yds is 5 yards.

quote:

Originally posted by Gerard:
0.5% of 1000yds is 5 yards.

yes your dead right mate! not 5 inches like I said.

Alf, there are several relatively affordable rangefinders on the market that will range an animal with much better accuracy than +/- 10 yds at 1000. It's easier to do with some models than others, and some require more careful technique to be sure of the range but can get the job done for those on a budget. More money gets more reliability and ease of use at even longer ranges. Mine will do the large, reflective targets you're talking about to well beyond 2000. Anything the size of a goat is pretty easy at the 1000 yd mark.

For those who have put in the trigger time and have their acts together, elevation isn't usually the problem. The wind is. That's where shooting the highest BC bullets you can find pays off.

Gerard, are you re-testing your BC's the way Barnes is or something? Noticed virtually none are listed anymore for the HV's on the website.

/

Hi Jon A,
Our BC numbers evolved into a mess over the years. The most reliable way we had of determining BC was to measure speed at two different distances and compute from there. As no skill of any special kind was involved in this work, it was left to three different sets of people to do, at various times. The nett result was pure fiction in some cases and no uniform standard. Yes, I am redoing the BC numbers from scratch and doing it myself. Some are better, some are worse, most are close and, once done, all will be right. With some 170 different bullets to work through, it will not be a quick process. Once a bullet has been evaluated, it will be linked from the load data page in a format similar to this. If you have a particular query, I may have already done the work and can get it onto the site for you. Otherwise I can move the bullet you enquire about towards the head of the unfinished list and let you know. If anyone has suggestions for additional data for the bullet info page, now is the time to tell me so that it can be worked into the page design. I will not put in a box for Sd numbers.

Alf, the Leicas are rated at a 0.5% error, not 5% which gets you within 5 yds. This is not a random error. In other words, if you have a pile of them one might read 995, one might read 1005 and the rest will read something in between. But the one that reads 995 isn't going to read 1005 if you range it over and over again, but will read right around 995 every time. The 0.5% is a possible error in absolute accuracy, not variation in precision.

So if you've compared your range finder to several others (which I highly recommend) you should already know if it tends to read a couple of yards short or long. But even if you haven't, the drop data you have collected for your rifle is most likely based upon distances from your range finder and will match up unless you switch units or have somebody else range with his--in which case you should have checked for a difference between the two beforehand.

You're right about the ratings. I've found one can usually expect only around 50%-75% of the rated range on something like a deer, depending upon the conditions.

As for others that will do it:

You listed the new Geovid and 1200. The old Geovid would--it's likely still better than the new.

I've never used it but by all counts the Swarovski shouldn't have a problem in decent conditions using good technique--it certainly has the power if you can hit the right thing.

If you can find one, a Vector 1500 will easily handle it. If you can afford one, a Vector IV/Locator Plus will do it probably farther than your rifle will shoot.




My Newcon LRB 7X40 (1500m model, on the left) would do it under the right conditions but it could be tricky. It easily had the distance, but picking out a small target was difficult. The 3000 Pro isn't even trying hard at that range. Here's how it'll do on stuff like pine trees:



Small beam divergence and target selection allow it to range deer out to where most rifles have gone subsonic....

Thanks Gerard, that's what I was guessing. Don't worry about me, I already measured the one I was interested in.

Jon A,
I make it to be 0.548 G1 @ 3000fps, what did you get?

The 173 30 Cal? I got .430 G1, corrected to Standard Metro sea level conditions, over 200 yds at an average of about 3250 fps.

Jon A,
I chrono at 5m and 95m. Will that make such a big difference? My range is 68m above sea level.

That change in range shouldn't have made the difference. Of course measuring over a longer range will be more accurate--making error in distance measurement and chronograph precision a smaller factor in the final total. But if anything, you can usually expect a lower BC measured over close distances because the coning/yawing, etc, of the bullet as it leaves the muzzle (which hurts BC) will make up a larger portion of the average. But that's not the case here since you measured higher. I'd personally opt for a longer distance but 95m should be workable if everything else is precise. Sierra measures over 150 yds so you aren't too far off from them. Shortening to 50m or so would make it very difficult to get meaningful numbers. But if you can space them out farther, I'd recommend it. You'll see the SD and ES of the BCs come down.

The big sources of error testing like this are chronograph precision/calibration and weather corrections.

If one chrono averages measuring higher or lower than the other, that will seriously skew the results, especially with such small separation. Calibrating the chronographs to one another is very important:



In my case, one Oehler read an average of 4 fps lower than the other measuring the same bullet (accounting for the 1 fps the bullet would lose between the two)--but it was consistent, all differences in the single digits. If one measures much higher on one shot, then much lower on the next shot, you need better chronographs. Had the difference been 10 or 20 fps and I hadn't checked, that would have skewed my numbers one way or the other depending upon which was used where. Or had the differences varied much from shot to shot, the results would have been much less accurate. You have to do this check to ensure accurate results.

Then weather conditions. As I understand it, one of the reason Barnes' BCs were so overrated in the past was they didn't properly correct things down to standard sea level conditions, and their test range was around 4000 ft altitude or so. At 68m you won't be nearly that far off for this reason, but you could be a good 10% or so depending upon the weather. "Standard Metro" temp is only 59 degrees and it's at sea level. A couple hundred feet elevation plus hot temps plus a low baro could throw you off close to 10% or so from standard conditions. Here's a free online calculator I've found to be pretty good: http://www.eskimo.com/~jbm/calculations/bcv/bcv.html

And finally, as with most measurements you want to be "scientifically accurate," you need a control. A standard. Never just measure one bullet at a time. You might have something screwed up in your setup or your corrections and you won't know unless you also test a bullet of a known value. When I tested the 173's, I also tested 7 others in the same sitting. Here are all the results:



I feel pretty confident in the accuracy of these results because of the six bullets that have current manufacturer's BC ratings, five of the six were within 5% or so. That's really pretty good considering how different barrels, twists, velocities, atmospheric conditions, etc can change BC's a bit. 5 of the 6 within 5% is pretty good validation of the test.

Also, I had already tested four of these bullets before. One was off 2.8% from the last test, the rest were pretty much right on the money. This, in addition to the above validates the latest test. When I test more in the future, I'll re-test one or two of these bullets just to make sure the results jive with the last test. If they don't, I screwed up the chronograph spacing, the weather correction factors or something else.

Happy testing!

quote:

Could you post a picture of the specific bullet and all it's dimensions, please?

Its the Hornady 7mm 162 Amax he is talking about and its BC is actually .625 pretty common, I use them in my 7mm-08.

Have a look here

https://www.hornady.com/shop/?ps_session=f53a9fec8dfd03...37de4558caf588c48018

Tumbo, using the above online BC calculator which Jon A "found to be pretty good" just to get an idea of how correct or overrated the 162gr Hornady A-max's BC is, I found the following:

The % drop in velocity over 100m should be in the region of only 5.7 to achieve a BC of 0.625.

Looking at the highest BC bullet in Jon A's above figures you'll see that a velocity drop of 8.2% gives a BC of 0.647.

Based on that I would say that the 162gr A-max starting off with a MV of 3000fps can at best have a BC of 0.430 with a lot of things in its favour! Otherwise even less than 0.400.

I know it is not scientifically correct to do a comparison this way, but at least it gives an indication that the Hornady BC's are somewhat overrated like Barnes' BC figures were in the past.

The 162 A-Max does not have a BC that low. What numbers are you looking at? Most of Hornady's plastic tipped bullets are actually very conservatively rated by them and will test much higher than advertised. The 162's advertised number is somewhat of an exception to that but how on earth are you coming up with .430 and .400? There's no way it's that low.

quote:

JBM Ballistic Coefficient (Velocity) Output
Input Data
Near Velocity: 3000.0 ft/s Far Velocity: 2549.0 ft/s
Distance: 300.0 ft Drag Function: G1
Temperature: 59.0 °F Pressure: 29.92 in Hg
Humidity: 0.0 % Altitude: 0 ft
Std. Atmosphere at Altitude: No Corrected Pressure: Yes
Calculated Parameters
Atmospheric Density: 0.1 lbs/ft³ Speed of Sound: 1116.5 ft/s
Ballistic Coefficient: 0.208 Time of Flight: 0.108519 s
14 Sep 2006 00:22:47, JBM [http://www.eskimo.com/~jbm]

Using some of the JBM calculators you "found to be pretty good" the velocity of a 162gr Hornady A-max will drop over 100yds to 2549fps from the originally quoted 3000fps stated by Paul from nz.

As you can see above that yields a BC of only 0.208 for the Hornady A-max.

However, common sense tells me it should rather be close to the GSCHV 173 namely 0.430 or even less, roughly 0.400.

Now don't tell me the JBM ballistic calculator is no longer "pretty good" at this!

Again, not scientifically perfectly correct, but it does indicate that BC of 0.625 is overrated on the Hornady 162gr A-max.

I'm asking where the 2549 fps number you entered into the calculator came from. I've re-read and re-read the thread and I don't see where Paul said he chronographed a 3000 fps load at 100 yds and found it to be 2549 at that distance.

HEY!!!

Jagter, where did you get the pictures of the bullets? I could care less argueing the bc's but I'm seriously bugged not knowing for sure if #2 is a North Fork or Groove? What else could it be, GS Custom? Do they make a flat base like this?

None of it matters really. We're bored. There are high bc bullets that won't work as well on game and high enough bc bullets that will. Truth is, most shots are so close a round nose flat base would be fine! Nate

Jon A, repeated the calcs below and got the same results -

quote:

Trajectory (Basic) Output
Input Data
Manufacturer: Hornady Description: .284 dia. 162 gr. A-Max
Muzzle Velocity: 3000.0 ft/s
Sight Height: 1.50 in LOS 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
Relative Humidity: 0.0 % Altitude: 0 ft
Std. Atmosphere at Altitude: No Corrected Pressure: Yes
Target Relative Drops: Yes Zero at Max. Point Blank Range: No
Calculated Parameters
Elevation: 3.34 MOA Azimuth: 0.00 MOA
Atmospheric Density: 0.07647 lbs/ft³ Speed of Sound: 1116.5 ft/s
Maximum PBR: 372 yds Maximum PBR Zero: 315 yds
Range at Max Height: 173 yds Energy at PBR: 2154.8 ft•lbs
Sectional Density: 0.287 lbs/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yds) (in) (moa) (in) (moa) (ft/s) (none) (ft•lbs) (s) (in) (moa)
0 -1.5 *** 0.0 *** 3000.0 2.687 3236.9 0.000 0.0 ***
100 -0.0 -0.0 0.5 0.5 2549.5

quote:

JBM Ballistic Coefficient (Velocity) Output
Input Data
Near Velocity: 3000.0 ft/s Far Velocity: 2549.5 ft/s
Distance: 300.0 ft Drag Function: G1
Temperature: 59.0 °F Pressure: 29.92 in Hg
Humidity: 0.0 % Altitude: 0 ft
Std. Atmosphere at Altitude: No Corrected Pressure: Yes
Calculated Parameters
Atmospheric Density: 0.1 lbs/ft³ Speed of Sound: 1116.5 ft/s
Ballistic Coefficient: 0.208 Time of Flight: 0.108508 s
15 Sep 2006 00:33:04, JBM [http://www.eskimo.com/~jbm]

I based my conclusions fully on the JBM calculators - can't say how accurate they are, but assumed that your approval thereof was sufficient.

BigNate, here they are - follow link.

They are not North Fork, Groove, Hornady, Nosler or whatever and least of all definitely NOT GSC's.

Hope hunters learn something from this thread and more about BC's specifically.

Goodness, Jagter. You entered the 300 yd velocity (though you've relabeled it as 100 yd above) from the trajectory calculator and entered that into the BC calculator which defaults to 300 ft, which is only 100 yds. This is how you got .208.

Even if you had done the above correctly (2845 fps @ 100), you still haven't measured anything. The first calculator is taking an assumed BC and giving you velocity results...the second is taking velocity results and giving you a BC. You're starting with assumed data and going round in a circle, ending up back where you started.

That's the whole point of measuring. Get a chronograph. Put it at 100 yds. Shoot the 162 over it. You'll find it to be going around 300 fps faster than the 2549 number you mistakenly entered into the calculator.

Jon A, sorry my mistake - didn't notice the default 300 figure already in the calculator as 300ft and not yds.

quote:

Even if you had done the above correctly (2845 fps @ 100), you still haven't measured anything. The first calculator is taking an assumed BC and giving you velocity results...the second is taking velocity results and giving you a BC. You're starting with assumed data and going round in a circle, ending up back where you started.

Seeing that the above is also true - running in crcles - can you test this specific bullet's BC for us?

Actually that is one I would like to test. It's just a matter of getting around to it...I keep the Oehlers separated by about 800 miles most of the time so it isn't the most convenient thing for me to do.

I'll put it on the list and try to include it in the next test I do. Pops has got a JRS that should really like that bullet....