I have a match I'm getting ready for and would like to confirm my truing method. At the range I have set up there are targets out 910 yrds should I be just truing with the furthest target? In the Applied ballistic app it gives you areas to put 3 sets of distances, should I be entering in all of these like say 640, 830 and 910 actual hits or just the furthest/closest to transonic?
- Thread starter CASCADE SHOOTER
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When I'm truing using my ballistic software I'll tend to use distances where I'm not likely to fudge my results with the human factor, just in case I'm on an off day, bad wind, or any number of human variables that can screw a shot and cause me to waste time and ammo. My range runs in 100yd increments, so I'll true at 300, 500, and 700yds. I use the shoot n see stickers so I can be pretty consistent, the small ones work good for the 300yd and the ones one size up from that work well for the 500 and 700yd distances.
Hornady's new listing of their velocity banded BCs should help clue some stuff in
http://www.hornady.com/BC
they list 3 different BC numbers, for say, the 140 eld match
.646 above 2512 fps / .637 for 2512-2232 fps / .616 below 1953 fps
so if you take a standard 6.5 short action 140 load and say its moving @ 2750 fps...its using the highest BC (velocity above 2512 fps), until about 175 yds...BC doesnt matter much at all...its using the mid range BC until about 400 yds where its now moving 2200 fps...BC doesnt matter much here either, using .646 gives me 1.79 mil of drop while, using the lowest of .616 gives 1.81 mil of drop...somewhere around a whopping .25" difference...
now once its stretched out to 800 yds...if you were using the .646 BC, your predicted drop would be around 5.76 mil...the .616 BC yields 5.88...starting to diverge a little...
@ 1000 yds, .646 yields 8.35...616 yields 8.58
point of all this, truing by adjusting velocity until about 500 yds (600-800 if pushing higher BC bullets faster than the example), and then past that, resort to tweaking BC...it works well...if you try to just adjust velocity at your furthest target, its going to put you slightly high in your close/mid range...if you try adjusting BC in the mid/close range, its going to have to change so much, it throws off your long range...this will put you in the familiar place of a lot of guys who cant get their DOPE to line up across the entire supersonic flight...the ol "its .2 high at distance A, but dead on out at B" stuff you always hear, or i always hear at least...the BC and velocity work together and understanding how they jive will make your truing process smooth and easy, and like the above posters mentioned, multiple, repeatable hits at distance to verify, seen guys miss 3 times, then hit once, and call it good and move on...doesnt usually work out too well for them
http://www.hornady.com/BC
they list 3 different BC numbers, for say, the 140 eld match
.646 above 2512 fps / .637 for 2512-2232 fps / .616 below 1953 fps
so if you take a standard 6.5 short action 140 load and say its moving @ 2750 fps...its using the highest BC (velocity above 2512 fps), until about 175 yds...BC doesnt matter much at all...its using the mid range BC until about 400 yds where its now moving 2200 fps...BC doesnt matter much here either, using .646 gives me 1.79 mil of drop while, using the lowest of .616 gives 1.81 mil of drop...somewhere around a whopping .25" difference...
now once its stretched out to 800 yds...if you were using the .646 BC, your predicted drop would be around 5.76 mil...the .616 BC yields 5.88...starting to diverge a little...
@ 1000 yds, .646 yields 8.35...616 yields 8.58
point of all this, truing by adjusting velocity until about 500 yds (600-800 if pushing higher BC bullets faster than the example), and then past that, resort to tweaking BC...it works well...if you try to just adjust velocity at your furthest target, its going to put you slightly high in your close/mid range...if you try adjusting BC in the mid/close range, its going to have to change so much, it throws off your long range...this will put you in the familiar place of a lot of guys who cant get their DOPE to line up across the entire supersonic flight...the ol "its .2 high at distance A, but dead on out at B" stuff you always hear, or i always hear at least...the BC and velocity work together and understanding how they jive will make your truing process smooth and easy, and like the above posters mentioned, multiple, repeatable hits at distance to verify, seen guys miss 3 times, then hit once, and call it good and move on...doesnt usually work out too well for them
I'm shooting a 6.5 creedmoor with the new nosler rdf 140 grain with a g7 of .330 at around 2800fps. What distance would you recommend trueing the bc and velocity to be able to get consistent hits between 400 and 1500?
what ive always done (recommended to be by some experienced shooters years ago) was true with velocity until 6-700 yds with all of my 6/6.5s...on a small target, 1moa or smaller...then past that i tweak bc out to 1000 (furthest i have to shoot for practice)...the smaller your targets the more accurate youll be able to true it up...i dont have anywhere to shoot 1500 yds, but this method has been solid and consistent out to 1200 yds in competitions...im my experience, if using a magnetospeed, you shouldnt have to adjust velocity a whole bunch...i think right now in my 6/6.5/28nos/308 loads im using the exact velocity or within 20 fps of what the chrono reads after truing them up
Ok went back out today shot 10 rounds over the magneto. Gave me a mv of 2790 put that in my kestrel. Zeroed at 100 and then went out to 810 (longest i had available) kestrel said 6.08 for elevation. 5.8 was above center and 5.7 was below center. So i trued the velocity in the kestrel with 5.75 mils at 810 yards. Gave me a mv of 2731. Is it really possible to have 60 fps difference from the magneto speed. Been told the bc of 330 on the 140 grain rdf bullets was gtg. Am i wrong to think thats not the case? Im loading 42.6 h4350 50 thousand off the lands. Avg mv was 2790 and Sd was 8.4. 2 rounds at 810 had a vertical of less than .25"
Nope. The BC varies with bullet speed.
True to BC using a known MV.
Alternatively if ur software allows try a variable BC as a function of bullet speed.
The more I learn about truing the kestrel. The more I rethink it or the truing anyway. I true using my scope as i am sure many do. but what if you scope does not track correctly? then your truing is not correct.Or i would think so am I wrong in assuming this?
Was thinking the same thing. I have a gen 2 razor and it seems like it tracks right. Going back out tomorrow to test at multiple targets at several different ranges to see if i get mixed results or not
Did that in my kestrel and it came out to .296 bc. The bc everyone has been using for this bullet is .330. Is it possible for it to be off that much concidering im pushing it at its upper end of the velocity scale?
mccaraudio, im confused because if im reading what you wrote correctly...
magneto+kestrel+.330 = 6.08, round it to 6.1 (this # doesnt seem right either, unless youre in a place with a REALLY low DA, in the negatives) did you have any crosswind taken into account in the kestrel?
actual was 5.75? but when you trued you got a LOWER muzzle velocity?
thats backwards...if you needed LESS elevation than predicted you would have to INCREASE velocity or BC
FWIW...guessing your scope height at 2.25, with your original 2790 fps and .330 BC, Ballstic AE gives 5.68 mils @ 0 DA
adjusting BC a bit...@ 0 DA, it gives 5.75 mils with a BC of .321 which is well within the ballpark
if your scope is slightly higher it will be a tenth or so less, if its lower, a tenth or so more
if it was me, i would drop the velocity a little bit, maybe 5-15 fps, and see if my close to mid-range still stays true, once i have that lined up out to 6-700, then i'd adjust BC to make the 810 line up, and go from there...for example, dropping to 2780 fps and BC to .325 gives 5.77 mils which is right in there...would just have to see how it influences your closer range DOPE
if youre equipment is true and tracks...
centered close - midrange: velocity on / BC can vary quite a bit
centered close - midrange, low at long range - velocity is close / BC is too high
high close - midrange, centered at long range - velocity is too high / BC is likely off as well
^^ all this assumes inputs from the user are all correctly accounted for
Crap i dont know i just stuck it back in my kestrel and i cant duplicate the numbers. I must of had something wrong. I only have 3 profiles. 1 for 2790 fps and 1 for 2730 fps and then 1 for prime 130s moving at 2920. I cant get 6.08 as a dope. Maybe i wrote the numbers down in my book wrong. It was windy and i was shooting off the top of my truck. Went out today and shot everything from 330 to 1320 and all my dope was good except i was hitting low at 700 yards. Came up a 10th on my dope and i was on the plate. Still learning the kestrel so im thinking i just had spmething fed up lol. Seems to be good to go now. Thanks for the help.
lol no worries, it happens...once you get familiar with what to tweak and where, truing up will be a quick process, just a handful of rounds and youll be good to go
You do not have to use the ranges listed in the box, however they are designed to be the most accurate. You should be shooting 5 shot groups, and it is also important that the environmental and target direction factors are accounted for.
Try out this. Take a 1 moa spread for your rifle at 300 yards. Take the dope for the lowest shot, and the highest shot. Compare the MV results. Then do it again at say 850 yards. Look at how large the spread is in velocity from the high to the low shot for a 1 moa rifle spread. Think about how much error is present between the two.
Try out this. Take a 1 moa spread for your rifle at 300 yards. Take the dope for the lowest shot, and the highest shot. Compare the MV results. Then do it again at say 850 yards. Look at how large the spread is in velocity from the high to the low shot for a 1 moa rifle spread. Think about how much error is present between the two.
1moa? I shoot a mil scope. Do i need to adjust like .2 above and shoot a 5 shot group and then .2 below and shoot a 5 shot group?
He's kinda a retard Morgan. Don't help him, he might shoot his eye out.
Wait a minute, when using the Applied Ballistics Kestrel 5700 Elite, it gives me the SINGLE recommended range at which to true the muzzle velocity of my 6.5 Creedmooe (I think around 1000yds) - not to use MULTIPLE ranges. If I understand Litz correctly in "Accuracy and Precision", using a range where MV is 1340-1228fps is most accurate.
are you talking about using litz custom curves and the truing that goes along with them? if so, i dont use them, not all the bullets ive shot in the past have them so i never bothered or needed them
everything ive mentioned works in any decent ballistic app, its not kestrel or AB specific
Most people do not have access to the ranges required to true via the AB Apps as recommended in the app.
On average I have found (mainly due to the 1300fps limit) it's well beyond 1000 yards. Usually in the 1400 yard range for something like your typical 6.5.
So using the methods noted regardless of the app is best.
On average I have found (mainly due to the 1300fps limit) it's well beyond 1000 yards. Usually in the 1400 yard range for something like your typical 6.5.
So using the methods noted regardless of the app is best.
When you find the distance for truing use
1061 plus temp of the day then times that by 1.2
Example 1051plus 70 = 1131
Times by mach 1.2 = 1357
Trans is Mach 1.2
Go into range card and look for that number in the velocity. That would put my target at 920 meters.
You can true within 10% of that range and be good. Adjust your calibration (cal MV) to what you hit the target with then your done.
You are going to seeing differences in MV when you chrono, so truing will fix the issue.
If you true too close into super sonic you won’t get the resolution you need because the cone of fire won’t be far enough apartin its separation thats why we do it at the lead edge of trans or 10%. Of that range.
I recommend using a truing bar. Just paint a horizontal line across you target. We are making sure we have hits with a MOA of that line. Wind is not a factor. Make sure spin drift is turned off.
1061 plus temp of the day then times that by 1.2
Example 1051plus 70 = 1131
Times by mach 1.2 = 1357
Trans is Mach 1.2
Go into range card and look for that number in the velocity. That would put my target at 920 meters.
You can true within 10% of that range and be good. Adjust your calibration (cal MV) to what you hit the target with then your done.
You are going to seeing differences in MV when you chrono, so truing will fix the issue.
If you true too close into super sonic you won’t get the resolution you need because the cone of fire won’t be far enough apartin its separation thats why we do it at the lead edge of trans or 10%. Of that range.
I recommend using a truing bar. Just paint a horizontal line across you target. We are making sure we have hits with a MOA of that line. Wind is not a factor. Make sure spin drift is turned off.
Hahahaha. Holly shit, I never even looked at the date. As they say better late than neverResurrecting this? Last post was from 2017
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