Making Software Jive?

[Bigwheels]

Kinda long, but please bear with me.
I've been using FFS for years, & have always been able to get verry accurate solutions with published BC's, & my chrony. Until now.
Since switching to Hornady's new 225gr HPBT, I have not been able to get anything close with any of the published BC's, & my chrony'd velocities.
There are several ways I can MAKE IT give me accurate solutions.
Baseline:
300WM with Hor 225 HPBT Moly'd
Published BC-.670
MV with my chrony-2820 fps.
29.78" hg, 67* F, 62% RH. @ 300' ASL (I use station pressure measured with my Kestrel)
Zeroed @ 100 yd. I went to a high altitude for some hunting, & did some ELR with this solution.
24.77" hg, 58* F, 45% RH, 5400' ASL Beautiful day. Ranged a rock @ 1304 yd, plugged the data in, & it gave me a solution for 38,8 moa. My round hit several feet high.
I went to the .690 BC I've seen here. Solution said 38.2 & was still feet high. I was making hits @ 35.7 moa.
The next day after I adjusted the BC to .711, & MV to 2860 I fired on a rock @ 1490. MY solution was right on target.
After I went, to JBM, & did some fiddling around with the G7 BC of .351, I was able to adjust my MV up to only 2840 fps & got the right solution for the conditions.(My chrony could be that far off I guess)
Now I can get the actual solution out of FFS several ways.
1- I can use what I made work, & call it good.
2- Use my measured MV of 2820, & a G1 of .750
3- Use the .690 BC, & MV of 2883 fps.
4- Use BC of .730, & MV of 2840 fps.
I've never had to do anything other than make a DK adjustment on any of the several other loads I've used in the past to get correct solutions, so which should I use?
Thanks for bearing with me. Looking forward to your replies.

 

[Broz]

Re: Making Software Jive?

I have two "Shooting Chrony's" If this is what you are talking about. They, in line, with the same bullet, read from 25 to 40 fps different. The same one is faster no matter which one is in front. I just purchased an Oehler 35.

So, if you have one of the little fold open "Chrony's" I would go with advertised BC's and adjust MV to match the actual drops. Of course, with in reason.

Jeff

 

[thekubiaks]

Re: Making Software Jive?

I think I understand what is going on. I use Exbal v 9.6 for my calculations and it is has a "sight in field conditions" section as well as a "Field/Range Conditions section. The way it is supposed to work (at least the way I understand it) is you enter all of your sight in field weather information and actual muzzle velocity, BC, etc. The Field/Range section will then correct the change in weather conditions.

What it sounds like in your case is that you are zero'd at sea level, went to a 5400' elevation field to shoot, looked at the new weather corrected range tables and are still shooting high. The BC of the bullet didn't change so I wouldn't change that, but I noticed that you didn't chrono your muzzle velocity in the field. Of course the velocity will be higher at 5400' above sea level, in fact 2860 - 2883 sounds about right. Therefore, your range table would have to be rerun with the new, higher velocity.

I think your range tables think you are at 5400' but your ballistics program thinks your muzzle velocity is still 2830fps which will tell you that you need more holdover.

Since you are shooting faster due to the higher altitude, the rounds are not decelerating as much as they would at sea level and you are going to go high.

I would plug in all of the sea level info into your ballistics program to get a powder weight matching your 2830fps muzzle velocity and then change the shooting altitude to the new field altitude (5400) without changing anything else just to get a new predicted muzzle velocity. Then you could have a range table for the higher field altitude with the "best guess" muzzle velocity. (You'll still have to fire a shot or two at the field to make sure you did your math right.)

 

[The Mechanic]

Re: Making Software Jive?

Don't use factories published data. Use Litz's data.
Also if I am not mistaken you can enter ENV data and do a 100 yard zero and your drop at longest distance you can to get your "correction factor" Someone correct me on nomenclature if I am wrong.

 

[Bigwheels]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thekubiaks</div><div class="ubbcode-body">I think I understand what is going on. I use Exbal v 9.6 for my calculations and it is has a "sight in field conditions" section as well as a "Field/Range Conditions section. The way it is supposed to work (at least the way I understand it) is you enter all of your sight in field weather information and actual muzzle velocity, BC, etc. The Field/Range section will then correct the change in weather conditions.

What it sounds like in your case is that you are zeroed at sea level, went to a 5400' elevation field to shoot, looked at the new weather corrected range tables and are still shooting high. The BC of the bullet didn't change so I wouldn't change that, but I noticed that you didn't chrono your muzzle velocity in the field. Of course the velocity will be higher at 5400' above sea level, in fact 2860 - 2883 sounds about right. Therefore, your range table would have to be rerun with the new, higher velocity.

I think your range tables think you are at 5400' but your ballistics program thinks your muzzle velocity is still 2830fps which will tell you that you need more holdover.

Since you are shooting faster due to the higher altitude, the rounds are not decelerating as much as they would at sea level and you are going to go high.

I would plug in all of the sea level info into your ballistics program to get a powder weight matching your 2830fps muzzle velocity and then change the shooting altitude to the new field altitude (5400) without changing anything else just to get a new predicted muzzle velocity. Then you could have a range table for the higher field altitude with the "best guess" muzzle velocity. (You'll still have to fire a shot or two at the field to make sure you did your math right.)

</div></div>
The post was going to be long as it was, so I left out a couple things you are referring to.
When I zeroed the rifle, & was chronying at the same time, at sea level, & established my MV, & Zero at that time. Set those conditions for my "Set Zero" on the PDA. This will calculate the solution as the scope was set @ those conditions, & adjust for new conditions from there.(same as your "sight in conditions)
Also, after the 1 st shoot @ 1304 yds, I returned to camp, & fired 5 rnds to re-confirm my Zero, & MV. My MV did go up from 2800-2820 @ that altitude, & my Zero went high by 1 click.
Even given those small changes the solutions given were WAY off.
I am using one of those cheap Shooting Chrony's, & I do not trust it for precise MV readings,(I actually have 2) but I can't see my actual MV being 2890 fps. I have no pressure signs. I'm going to stack up both my chrony's, & a friends Beta Master to see what they say, but like I said in the OP. I have always been able to get good solutions with this chrony, & published BC's before. This bullet/load is just shooting flatter than predicted. It was doing the same with the Retumbo load @ 2865 too, but that was too hot for warm temps.

 

[Bigwheels]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: The Mechanic</div><div class="ubbcode-body">Don't use factories published data. Use Litz's data.
Also if I am not mistaken you can enter ENV data and do a 100 yard zero and your drop at longest distance you can to get your "correction factor" Someone correct me on nomenclature if I am wrong. </div></div>
Unfortunatly, Brian hasn't posted any testing of this bullet yet that I'm aware of.I did e mail him about it tho.
I have an older version of FFS, & I used the scope "fixed zero" with my original zero/MV data from sea level.
Now I looked back to Dave Tooleys posts about his doppler testing of this bullet, & his BC's are lower. (G1-.668, & G7-.336) If those BC's are correct my little 300WM should blow up if I'm pushing this bullet to that kind of speed!

 

[The Mechanic]

Re: Making Software Jive?

Speed will also affect BC. You can have a bullet that will change BC as its FPS decays.
Not sure what you mean by the "fixed zero" but If I remember it was adjusting the "DK".

 

[Bigwheels]

Re: Making Software Jive?

The "fixed zero" in FFS is the way it sets the conditions when the scope was zeroed, so it can calculate the differences from that "fixed" scope setting zero to account for changes in atmospherics. Otherwise the program will assume the scope was zeroed @ the new atmospherics every time they change.

 

[The Mechanic]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bigwheels</div><div class="ubbcode-body">The "fixed zero" in FFS is the way it sets the conditions when the scope was zeroed, so it can calculate the differences from that "fixed" scope setting zero to account for changes in atmospherics. Otherwise the program will assume the scope was zeroed @ the new atmospherics every time they change.</div></div>
That sounds more like PBZ. Parallel bore zero.

 

[Bigwheels]

Re: Making Software Jive?

As I understand it, the program uses the zero fixed as the base line for changing atmos. So if I zero @ sea level @ 100 yds @ 65*F, & set my fixed zero there, & go to 6000', @ 80* F the program compensates for the difference from the zero @ sea level. If I didn't fix the zero, it will assume that the scope was re zeroed @ 6000', & 80* F for the solution. So it does the same thing as Exbal's "sight in field conditions".

 

[Eaglet]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bigwheels</div><div class="ubbcode-body">Kinda long, but please bear with me.
I've been using FFS for years, & have always been able to get verry accurate solutions with published BC's, & my chrony. Until now.
Since switching to Hornady's new 225gr HPBT, I have not been able to get anything close with any of the published BC's, & my chrony'd velocities.
There are several ways I can MAKE IT give me accurate solutions.
Baseline:
300WM with Hor 225 HPBT Moly'd
Published BC-.670
MV with my chrony-2820 fps.
29.78" hg, 67* F, 62% RH. @ 300' ASL (I use station pressure measured with my Kestrel)
Zeroed @ 100 yd. I went to a high altitude for some hunting, & did some ELR with this solution.
24.77" hg, 58* F, 45% RH, 5400' ASL Beautiful day. Ranged a rock @ 1304 yd, plugged the data in, & it gave me a solution for 38,8 moa. My round hit several feet high.
I went to the .690 BC I've seen here. Solution said 38.2 & was still feet high. I was making hits @ <span style="font-weight: bold">35.7 moa.</span>
The next day after I adjusted the BC to .711, & MV to 2860 I fired on a rock @ 1490. MY solution was right on target.
After I went, to JBM, & did some fiddling around with the G7 BC of .351, I was able to adjust my MV up to only 2840 fps & got the right solution for the conditions.(My chrony could be that far off I guess)
Now I can get the actual solution out of FFS several ways.
1- I can use what I made work, & call it good.
2- Use my measured MV of 2820, & a G1 of .750
3- Use the .690 BC, & MV of 2883 fps.
4- Use BC of .730, & MV of 2840 fps.
I've never had to do anything other than make a DK adjustment on any of the several other loads I've used in the past to get correct solutions, so which should I use?
Thanks for bearing with me. Looking forward to your replies. </div></div>
Bigwheel, check this out.
The given information was used with LoadBase 3.0 and here are the results:

MV = 2820 fps
BC(G1) = 0.670
DC = 0.500
SH = 1.5”
ZR = 100 yards

Sight In Conditions - Barometric

Air Press = 29.78 Inch/hg
Temp = 67ºF
RH = 62%
Alt = 300 feet

Field Conditions - Barometric

Air Press = 24.77 Inch/hg
Temp = 58ºF
RH = 45%
Alt = 5400 feet

<span style="font-weight: bold">PATH a 1305 yards = <span style="color: #660000">35.7 MOA </span></span>

 

[CoryT]

Re: Making Software Jive?

Has the scope been calibrated and that adjustment entered into FFS? That alone could be the issue. Otherwise, adjust the velocity first, as much as 6-8%, chronos, especially cheap ones are just not that precise. If further adjustment is needed, adjust the BC, as much as 5%, Then do the DK adjustment as described inthe manual.

Note that a succession of small errors can drive the system to the wrong solution. Velocity low, BC low, scope off by .02 MOA, pressure off by .05, temp off 5 degrees, range off by 5 yards, plus a little up/down angle. Add all those very minor errors up and you get what appears to be a bad solution.

A certain amount of tweaking will be required, hopefully during a couple of range sessions using the same equipment and carefully shooting groups on paper, taking precise measurements.

 

[V-Ref]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bigwheels</div><div class="ubbcode-body">Kinda long, but please bear with me.
I've been using FFS for years, & have always been able to get verry accurate solutions with published BC's, & my chrony. Until now.
Since switching to Hornady's new 225gr HPBT, I have not been able to get anything close with any of the published BC's, & my chrony'd velocities.
There are several ways I can MAKE IT give me accurate solutions.
Baseline:
300WM with Hor 225 HPBT Moly'd
Published BC-.670
MV with my chrony-2820 fps.
29.78" hg, 67* F, 62% RH. @ 300' ASL (I use station pressure measured with my Kestrel)
Zeroed @ 100 yd. I went to a high altitude for some hunting, & did some ELR with this solution.
24.77" hg, 58* F, 45% RH, 5400' ASL Beautiful day. Ranged a rock @ 1304 yd, plugged the data in, & it gave me a solution for 38,8 moa. My round hit several feet high.
I went to the .690 BC I've seen here. Solution said 38.2 & was still feet high. I was making hits @ 35.7 moa.
The next day after I adjusted the BC to .711, & MV to 2860 I fired on a rock @ 1490. MY solution was right on target.
After I went, to JBM, & did some fiddling around with the G7 BC of .351, I was able to adjust my MV up to only 2840 fps & got the right solution for the conditions.(My chrony could be that far off I guess)
Now I can get the actual solution out of FFS several ways.
1- I can use what I made work, & call it good.
2- Use my measured MV of 2820, & a G1 of .750
3- Use the .690 BC, & MV of 2883 fps.
4- Use BC of .730, & MV of 2840 fps.
I've never had to do anything other than make a DK adjustment on any of the several other loads I've used in the past to get correct solutions, so which should I use?
Thanks for bearing with me. Looking forward to your replies. </div></div>

I have had this happen to me a couple times myself...great advice already posted above...my contribution based on when this has happened to me is, these problems were either highlighted/resolved with-
1. Re-Verify the 100 yd zero under the 5400'ASL conditions. I'd also put a plug in for a 200 yd or 300 yd zero for your next LR session. It seems I always have better results with first round precision @ distance with zeros at greater distances than 100 yds.
2. Track test your optic. Vise up the rifle, yard stick/tape measure @ 100 yds, track test the optic at 5 MOA increments up to your 1490 yd solution.
3. Bring along a data card (or a Droid Shooter .pdf) for the anticipated field conditions. While it won't be as precise as the FFS data using real time enviros, the range card will allow you to compare the real time enviro FFS solution vs. the data card, and highlight a potential data entry error/omission in your FFS while in the field..vice at the house on JBM after the range session.
4. Review your lighting conditions when you chrono'd these rounds. Since you've had good results previously with your system, I suspect your MV is the culprit here.

Hope this helps. Look forward to hearing what resolves this issue for you.

 

[Bigwheels]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CoryT</div><div class="ubbcode-body">Has the scope been calibrated and that adjustment entered into FFS? That alone could be the issue. Otherwise, adjust the velocity first, as much as 6-8%, chronos, especially cheap ones are just not that precise. If further adjustment is needed, adjust the BC, as much as 5%, Then do the DK adjustment as described inthe manual.

Note that a succession of small errors can drive the system to the wrong solution. Velocity low, BC low, scope off by .02 MOA, pressure off by .05, temp off 5 degrees, range off by 5 yards, plus a little up/down angle. Add all those very minor errors up and you get what appears to be a bad solution.

A certain amount of tweaking will be required, hopefully during a couple of range sessions using the same equipment and carefully shooting groups on paper, taking precise measurements. </div></div>
Yes, the scope has been verified accurate.(NXS 5.5-22 X 56) The info on atmos is measured with a Kestrel. The only parts of the equasion I can't verify is the range, (measured with a swaro LRF, & the MV (I have cheap chronys). I trust the LRF more than the chrony, & like I posted in the OP, I have always been able to get real close with published BC, & MY chronys before with 220 SMK, 210 VLD, & 208 A Max.(usually a DK adjustment of about .0025 +/-)
My next range session will be re testing EVERYTHING again with a friends chrony, etc. & known ranges that I've had set up for several yrs.

 

[CoryT]

Re: Making Software Jive?

Well, the Swaro is likely to be pretty close, but depending on the terrain it's possible to have a signifigant error. Anmy error in the Kestrel is normally too small to make much of a differance, unless it's not the same meter you used to get the original zero, even then that's not the sole sorce of the problem.

Even with an NXS, I'm usually suprised if the scope tracks EXACTLY correct. I don't any scopes that are not off some small amount, that includes 3 S&B's. That's does not mean it's not spot on, but it may be worth checking again.

Best to setup truly known distances, 100, 500, 1000 and 1500 if possible, using paper to track a good group, shoot the group over the chrono and track each impact with it's velocity. This has always let me get very good tracking from the system, though it's rather a chore to setup.

 

[Bigwheels]

Re: Making Software Jive?

The hillside I was ranging on was steep, with a few burned standing trees, so the ranging error shouldn't be significant. That's exactly what I'm planning on doing next time out. I'll re check the scope, although I'm pretty sure that's not it, & I'm going to use the targets I have set up that have been ranged by my LRF, a few Leicas, a PLRF, & Google Earth, so I know they are +/- a yd accurate. Try a different chrony, along with my 2, all in line if I can, & see what's up. I guess, that as long as I can get the program to give me accurate solutions, I don't really care if the numbers all jive with the published numbers, but I'd like them to. Never had the program be this far off before. Just aggravating!
Thanks for the help. I love this bullet, & the new load shot a .193" group @ 100 last time I checked zero, so I really want this to work. I have a match on 9/10 I want to shoot with it.

 

[Eaglet]

Re: Making Software Jive?

Sorry for the delay, I was not using my head right and the... Never mind. When using the original data in LB3.0 the correction given is 35.7 MOA which is what you were using to make hits with.

Here are some pics that include environment conditions for sight in and field environment conditions:

 

[CoryT]

Re: Making Software Jive?

Eglet, you'll need to re-run that, as he's using station pressure and not baro pressure. The near sea level zero condition won't be far off, but the field condition will be off a considerable margin, since baro pressure at that temp/alt is probably closer to 30.00 than 24.77

 

[Bigwheels]

Re: Making Software Jive?

Eaglet. Could you re run that using station pressure, & a sight height of 2.3"? I'd like to see what another program says. I've only used JBM, & FFS, & neither will give me the correct solution with the listed info. Thanks.

 

[Eaglet]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CoryT</div><div class="ubbcode-body">The near sea level zero condition won't be far off, but the field condition will be off a considerable margin, since baro pressure at that temp/alt is probably closer to 30.00 than 24.77 </div></div>

You're definitively right!

 

[CoryT]

Re: Making Software Jive?

Just FYI, I get the same 38.8 from PSW and Infinity.

As an error test, be advised that a 50 yard range error gets you to 35.7, as does an 80fps change in velocity and .03 MOA scope error, which is 3" in a 40 MOA dialup at 100 yards.

Start combining those errors in even smaller numbers and you see where this is going. Think 20 yards error, 40 FPS and .01 scope, all well within the range of possibilities.

 

[Bigwheels]

Re: Making Software Jive?

I recently went to Google Earth, & zoomed in to the area, & used the ranging app in there to verify the range for the 1490 yd shots.(I have had verry accurate results with it every time I've used it.) I couldn't see the spot where the 1304 yd spot was well enough to confirm it.(it was verry close) The elevation on the 1490 yd shot was 40' lower than the FFP. I used my CS indicator to find the rock to do everything I could to eliminate any angle. I rechecked the scope this morning on a yardstick @ 100 yds, & it is as close as I can split hairs with the lines. So I'll limit the error to MV, & BC. I trust the Kestrel, & the range jives with the LRF. I'm not a geometry guru, but 40' over 1500 yd can't be a significant angle of fire. I also spent about an hour going through all the different combinations of inputs that would give the correct solution, & I still can't get a solution without a large change in either MV, or BC, or a moderate change in both.

 

[Eaglet]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bigwheels</div><div class="ubbcode-body">Eaglet. Could you re run that using station pressure, & a sight height of 2.3"? I'd like to see what another program says. I've only used JBM, & FFS, & neither will give me the correct solution with the listed info. Thanks. </div></div>

Following your request it spits out 38.6 MOA at 1305 yards.

Now there is something else to be considered. Did you get the altitude from the the same kestrel or from another device? There would be an explanation why what I did matched what it was suppose to be but I would need to know if as the kestrel was yielding STAT pressure allowed you also to get an Elevation.

 

[Bigwheels]

Re: Making Software Jive?

Yes. All my temp, press, etc is done with the same Kestrel. I also have a Casio Pathfinder, that matches my Keastrel's press readings. The altitude is from Google Earth, & my intimate knowledge of the area. I don't use anything but station pressure on the program. I just gave the elevation for reference.

 

[Eaglet]

Re: Making Software Jive?

Got you!

Back to zero!

 

[CoryT]

Re: Making Software Jive?

>>I rechecked the scope this morning on a yardstick @ 100 yds,

That's probably not an adequate check for this kind of work. I'd get a 6 foot high target, use a tape measure to get 100 yards exactly, then either use groups every 10 MOA up to 60 or a laser to find the actual adjustment values. I've seen jumps, missed clicks, etc and the error we are looking at here is pretty hard to see on a yardstick through the scope.

If a less than 10% change of BC and MV get you there, you are in pretty good shape in any event.

 

[CoryT]

Re: Making Software Jive?

Not to be neglected is the effect of a updraft given you were slightly upslope of the target area. Even a couple MPH, almost invisible, could also account for the issue.

 

[Bigwheels]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CoryT</div><div class="ubbcode-body">Not to be neglected is the effect of a updraft given you were slightly upslope of the target area. Even a couple MPH, almost invisible, could also account for the issue. </div></div>
I've been considering that as well. There was a 1.5-2 mph breeze blowing up the valley in the mornings, & the crosswind value was 1.1 moa, so a slight updraft value could account for a 1/2 moa value. However the valley floor was very deep where I was shooting, so any updraft should have been negligable. Not discounting it tho.

 

[Bigwheels]

Re: Making Software Jive?

I just finished going over some other variables.
If I adjust the BC to the .711 G1 that Hornady came up with from shape estimates, & bump my MV up to 2840 fps, & allow for a -1* down angle.(which I found the 40' elevation difference with google earth) & allowing for a click or 2 for an updraft I get what I saw in the feild. But even there If I use the published BC, I need to bring my MV up to 2880+ to get it there, & I'm pretty certain I'm not pushing these bullets that fast. If I use ChadTRG42's BC of .690, I can get there with 2850 fps +/-. This isn't what my chrony said, but is within reason. If I account for a slight range error it's closer still.
I'm going to try for some field time in the next few days to see if I can sort this out.
Thanks for the brainstorming guys. This is why I love this site.

 

[Bigwheels]

Re: Making Software Jive?

Well, I did some work on the rifle today. Set up both my cheap chrony's back to back, centered, & leveled them in perfect alignment with the bore, & verified my zero with 10 rnds. My zero was still 1/4 moa high, so I set that down, & for the first 4-5 rnds my chrony's were a ways apart in the 2840's. Sometimes they were over 30 fps apart, but after that they settled down, & were only 1-3 fps apart for the rest of the string. Average for the load was 2837 fps. I then went out to my "usual" 750yd tgt, & sent a few. They hit about 1/2 moa higher than predicted using my new MV, & .690 BC. But this spot has a history of updrafts, & given the 1/2 value wind for the range as an updraft it was real close. I then went out to the other "usual" 860 yd tgt, & re checked the atmos, etc. & sent a few, & they all hit real close too. I wanted to go to my 1250 yd tgt, but it was so overgrown that I'd have to spend an hour with a weed whacker to cut a firing lane, so I bagged that idea. I'll be up there again next week with a friend to recheck the settings on FFS & help out with my buds 338 Edge for his upcoming moose hunt. So this confirms the .351 G7(.690 G1) that Chad TRG42 computed @ the 2840 fps MV using JBM was right on. So I THINK I have this nailed down finally. I'll confirm it all next week.
Thanks for all your responses.

 

[Eaglet]

Re: Making Software Jive?

Well that's good news. Great!!!

 

[V-Ref]

Re: Making Software Jive?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Bigwheels</div><div class="ubbcode-body">Well, I did some work on the rifle today. Set up both my cheap chrony's back to back, centered, & leveled them in perfect alignment with the bore, & verified my zero with 10 rnds. My zero was still 1/4 moa high, so I set that down, & for the first 4-5 rnds my chrony's were a ways apart in the 2840's. Sometimes they were over 30 fps apart, but after that they settled down, & were only 1-3 fps apart for the rest of the string. Average for the load was 2837 fps. I then went out to my "usual" 750yd tgt, & sent a few. They hit about 1/2 moa higher than predicted using my new MV, & .690 BC. But this spot has a history of updrafts, & given the 1/2 value wind for the range as an updraft it was real close. I then went out to the other "usual" 860 yd tgt, & re checked the atmos, etc. & sent a few, & they all hit real close too. I wanted to go to my 1250 yd tgt, but it was so overgrown that I'd have to spend an hour with a weed whacker to cut a firing lane, so I bagged that idea. I'll be up there again next week with a friend to recheck the settings on FFS & help out with my buds 338 Edge for his upcoming moose hunt. So this confirms the .351 G7(.690 G1) that Chad TRG42 computed @ the 2840 fps MV using JBM was right on. So I THINK I have this nailed down finally. I'll confirm it all next week.
Thanks for all your responses. </div></div>

Look forward to your results at 1250. Short of the steps you've just taken...I don't know any other way to do it anymore. Two chronos, verify the zero (preferably at 200-300 yds vice 100 yds), track test your optic, and then confirm drops at multiple distances with 2 sources of atmospherics/drop data, to ensure your range day isn't wasted because a wx station/pda/battery fails on you...

What a PITA....look forward to your 1250 yd test results.

 

[Bigwheels]

Re: Making Software Jive?

I just found the drag function conversion on JBM, & ran the .351 G7 that ChadTRG42 came up with. That BC @ 2840 was as close as I could get with what I had in the field. Anyway I did the conversion, & it came up with .704 G1. I plugged that into my FFS, & now I'm not sure it was an updraft. Hopefully I can get out & shoot with almost no wind next week to make sure. But at least now I'm confident of my MV, & I need only determine which BC I need. Leaning toward the .704 for now.
Thanks guys. More to come.

 

[Bigwheels]

Re: Making Software Jive?

Did some testing today starting @ 525 yd, & using my 2840 MV with the .704 G1 BC I got from JBM converting the G7 BC ChadTRG42 came up with. Started @ about 10:00 in the morning when temps, & mirage weren't bad yet. I was hitting slightly high @ 525 yd, Also @ 560yd. so we went out to 750 yd, & was hitting high by slightly more than 1/4 moa. So we cleared the shooting lane for the 1250 yd tgt, & was hitting 3/4 moa high.
I ended up making a DK adjustment to .5035, & that seems to have fixed it. So now my software settings are:
Zero conditions-28.01"hg(station pressure)/73*F/50% rh zero @ 100 yd.
MV of 2837 ave with a temp deviation of .5 fps/F*
BC of .704 with a DK of .5035
Sight height of 2.3"
Hopefully I will have a chance to go back up to 5500" ASL to check it again @ 1500 yd +, & confirm that the settings are true.
Thanks again for all your suggestions/comments. I appreciate it.

 

[Ring]

Re: Making Software Jive?

go here
http://www.longrangehunting.com/ballistics.html

enter your data...

go to step 2, enter data and hit "validate"

now enter you longest range real world dope, it will recalculate the right BC or FPS to match your data to give you good info...

 

[Bigwheels]

Re: Making Software Jive?

I have been gone for a while, & just got back from another range session to check out my software, & am still baffled by this bullet. I can make the software jive with my real world dope, but not with the posted BC, & my MV which was tripple checked with 3 chrony's to be 2837 fps. Twice with my 2 chrony's set up back to back giving exactly the same readings within 2 fps over a 20 rnd string.
To get any software to jive (inc. FFS, JBM, & now my iphone) I have to bump the MV up to 2880 fps, or bump the BC up to .711G1, or .375G7.
I even went back to my old 208 A-Max load which I have used effectivly for a few yrs, & that load still jives with my chrony's MV, & the posted BC of .649G1, so I can be assured that my scope clicks are close enough to not be an issue.(it also wasn't an issue with the previous 220 SMK, & 210 VLD loades with the same rifle, & scope combo)
I just don't understand what the problem could be at this point. A "minor" adjustment I can live with, but this is a large difference, & I just don't get it.
Any new thoughts?