|
|
|
Discussion Forums
Forum Index
> Precision long range hunting and shooting
> Drop chart data HELP!!
Drop chart data HELP!!
@ 07:20 am (GMT) |
Chris McKoySo.. a 2 day hunting trip ended hours ago, with the goal of taking long range shots on video, that was not to be as the new rifle was so far off JBM drop charts it went over the top of two animals.Rifle is sighted at 100m shooting at 2840fps using 285 amax Sighted in a rock at bang on 350m and shot the 1.9 mil JBM said to, way high. Rock was killed when dialed at 1.2 mil. I cant for the life of the find any combo of bc and velocity that gets me 1.2 mil at 350m, and short of going into the hills for the specific task of verifying drop charts, I'm a bit stuck. Any direction would be awesome! |
Replies
@ 04:30 pm (GMT) |
Bryan WebsterRe: Drop chart data HELP!!Shoot your rifle at targets out to the range you consider you might try to kill an animal at. Personally I would do 5 shot groups every 100 meters with the rifle sighted in at 100 meters out to 600 meters or so. Leave 5 minutes between shots for your group, as most hunting will be from cold bore shots. Then after that, I would think if your application for drop charts can be calibrated using the data that you have collected from your own shooting, you will have a meaningful drop chart.I would also add that knowing your muzzle velocity is paramount. Your scope's height above the rifle bore would be good to know was accurate as well. Hope this helps. I found while drop charts are very nice, I had to do the above to be sure. |
@ 08:36 pm (GMT) |
Nathan FosterRe: Drop chart data HELP!!Hi Chris, you have two factors. The first is that the BC of the A-Max in this barrel is running way higher than advertised. I talked about how the barrel has the final say on BC in my third book, something few other authors talk about. This batch of barrels lift the BC by .1 which is huge. This can only be tested as Bryan talked about.The next factor, is that you have to test your scope to see how its calibrated. That's all I am going to say here as my next book is due out soon and has a full methodical approach. |
@ 10:15 pm (GMT) |
Bob MavinRe: Drop chart data HELP!!Hi ChrisIs that 285gn pill? What calibre are you using? I use Sierra infinity with good results. Cheers Bob |
@ 11:48 pm (GMT) |
Martin TaylorRe: Drop chart data HELP!!Regardless of calibre you must verify your POI, equipment & charts under cold bore field conditions! Then as the guys have said you can manipluate the chart to suit.As Nathan has said bc's are not a given and neither are your scope adjustments or many other variables. Have a go at this little test! Shooting off a bench and prone at 100 & 300, changing between sand bags, soft rest and a bipod. The POI shifts will amaze you which is why you read warning of it in everything Nathan writes. l ‘m certain it will be heavily covered and drummed home in his new book! |
@ 01:51 am (GMT) |
Mike NeesonRe: Drop chart data HELP!!Chris, were you using the manufacturers bullet data or the Bryan Litz data? Where Mr Litz has actually tested the BC of the bullet, his data is available next to the manufacturers denoted by (Litz). Also what was the altitude and temperature? I have got a rough elevation of 1.5mil so far, but need the environmentals to be more "accurate". |
|
@ 01:58 am (GMT) |
Mike NeesonRe: Drop chart data HELP!!Also angle of shot will have an effect too... |
@ 04:44 am (GMT) |
Ben LawRe: Drop chart data HELP!!i notice hornady now list the bc of the 285 amax at .778, im sure they listed it as .72 not long ago. |
|
@ 07:54 am (GMT) |
Chris McKoyRe: Drop chart data HELP!!Thanks for the interesting replies people.. for clarity... rifle is in .338 caliber, I have noted the increased BC of this barrel. However, changing the BC of the bullet on JBM makes next to no difference until you go as high as 1.0 (increases by 0.1mil @350m). Just today I have confirmed the velocity at 2840fps through a 2k dollar chroni and the scope is verified with a matrix test (nightforce ATACR). I think the only way I will figure this is testing at each range in the field.Does anybody know a ballistics program that will accept known drops? Thanks people, help always welcome. |
@ 08:20 am (GMT) |
jasonRe: Drop chart data HELP!!Yes. I'm fairly sure the one at long range hunting forum does.Go to there website long range hunting forum. You should find a tab thats to a drop calculator. It's free. And iv found it good in the past. I havnt used it in ages. But I'm sure you can put in known drops. There are video clips to go with it. Sorry I can't give you a link or anything. I'm on a phone. I'm also fairly sure this site has a tab of links to related things and long range forum is on there. Good luck. |
|
@ 10:48 pm (GMT) |
Bryan WebsterRe: Drop chart data HELP!!Quote: Does anybody know a ballistics program that will accept known drops? Thanks people, help always welcome. http://appliedballisticsllc.com Has an iPhone App that will do what you need I got mine at the Apple Apps store by searching for 'Applied Ballistics' Works very well. |
|
@ 11:32 pm (GMT) |
Mike NeesonRe: Drop chart data HELP!!On Android devices you can get "shooter" for free. It is basically the applied ballistics app - exactly the same but doesn't have the reticules. |
|
@ 04:23 am (GMT) |
Martin TaylorRe: Drop chart data HELP!!As Nathan has said Chris, we had a very similar result working up a TF .338 barrel, massive differance. Large bc increases where needed when setting up charts to suit this barrel-285 Amax combo. Once sorted it is blisteringly accurate out past 1000.But as l said we confirm every rifle l set up under field conditions @ 100 & 300 then when we head up into one of our spots in the hills at 750 as a final. Here is a quote from Nathan in your last post "Nice! Next step BC testing. Fantastic." Why take a LR shot at an animal if you haven’t even set up the basics? You owe your game a lot more respect than that and even more so with the reach you have! |
|
@ 04:26 am (GMT) |
Bryan WebsterRe: Drop chart data HELP!!I was just looking at yet another app I have on my iPhone. Name is iStrelokand it works quite well and has trajectory calibration options. One thing I really appreciate about this one is their library of reticles is huge and they appear to be accurately executed. Comparing this and the above two options, I would lend my preference to the Applied Ballistics one. The free one is good too, but there are lots of little things I like better on this one and I can pay the very low cost. |
|
@ 04:42 am (GMT) |
Bob MavinRe: Drop chart data HELP!!I use Sierra Infinity.But whatever you use, it still has to be tested & refined real time in the field. Bob |
@ 04:52 am (GMT) |
Mike DavisRe: Drop chart data HELP!!ok I cant resist putting in a plug for DallanCwww.huntingnut has a pointblank programme on there the pointblank online is free and easy to use, go to top left box on main page and follow your nose. the beauty of this is you can bugga around with it quickly /keep changing things and watching the results. it draws out your trajectory curve for you which helps thick buggas like me work out what goes on. you can change any one of the thing you put in to change it to fit eg keep tootooing with your BC till your curve gets close and then jam it into your other programme if you want to. you can right click on the screen and it will save it to your computer. hope that helps |
|
@ 04:57 am (GMT) |
Chris McKoyRe: Drop chart data HELP!!Quote: As Nathan has said Chris, we had a very similar result working up a TF .338 barrel, massive differance. Large bc increases where needed when setting up charts to suit this barrel-285 Amax combo. Once sorted it is blisteringly accurate out past 1000.
But as l said we confirm every rifle l set up under field conditions @ 100 & 300 then when we head up into one of our spots in the hills at 750 as a final. Here is a quote from Nathan in your last post "Nice! Next step BC testing. Fantastic." Why take a LR shot at an animal if you haven’t even set up the basics? You owe your game a lot more respect than that and even more so with the reach you have! Cheers Martin good to know others have experienced similar results with the TF batch. Just to clarify, only one shot was made at 350m which shouldn't have been a problem when aiming at the front of the shoulder, the rifle was then used to shoot a rock at 350 and then put away for the trip. The only reason I ask about ballistics programs now is in order to get on paper to verify drops, there is no way I'm about to trust an app and just use it as is on animals. |
|
@ 03:30 pm (GMT) |
Bryan WebsterRe: Drop chart data HELP!!Apps still have their place for creating drop charts. As well, many of them can give decent windage corrections and can be used to adjust for changes in elevation (hunting in high mountains instead of sea level for example) as well as temperature and air pressure adjustments. Extreme long range shots may require such adjustments, but I do not consider those kinds of shots myself for animals...but targets and steel they can help you learn a bit.Once I get everything configured, I load the info into Infinity 7 and print a drop chart to help in field reference while hunting. For steel banging or targets I just use the iPhone apps. I also have a small chart which given changes in temps, elevation and humidity, I can manually make an adjustment. Great for steel but as I said I do not even bother with shots at game over 600 meters normally... That being said, I know how and have made consistent cold bore shots on small steel targets out to 800. |
Please wait
ABOUT USWe are a small, family run business, based out of Taranaki, New Zealand, who specialize in cartridge research and testing, and rifle accurizing.
|
KNOWLEDGEBASE |
KNOWLEDGEBASE |