FFS & Shooter past 1K.

Bigwheels

Bigwheels

Gunny Sergeant
Full Member
Minuteman
    • Jun 16, 2007
    1,819
    298
    58
    Anacortes WA
    #1
    I have been attempting to true both my FFS, & Shooter ap to my 300wm with 225gr hpbt. I verified zero, chronied the load, calibrated the scope out to 60moa, & did a check @ 750yd, & 1250yd at my home range. Did a DK adjustment to FFS. Then changed the mv, & bc to get Shooter ap to give the same dope. I was confident they were both as close as I could make them.
    Fast forward to last weekend I was on the other side of the state, & above 5000' asl, & over 4000' higher than my home range. I was ranged some rocks @ 1230yd, 1590yd, & 1740yd. Up there FFS was only off by 1/4-1/2moa high. So I adjusted the DK, & tried 1590yd, & was a 1/4 low so I adjusted the DK again, & tried again. This time I was spot on for 10 consecutive shots just missing a rock about the size of my head @ 1590yd. Missing a couple inches high, low, & sideways, but only by a few inches. I was about 1/4moa high again @ 1740yd. I was thrilled!
    Now I checked the Shooter ap with all the same atmos, etc. & its calculations were off by more than a whole moa! This is with the G7 I was using as opposed to the G1 of FFS, & all the scope corrections, & everything. At 1740yd it was off by almost 2 moa. I don't understand the difference between the two softwares given all the same inputs.
    I was very happy with my accuracy, & the accuracy of FFS.
    For those who may be interested. The rifle, & load:
    Custom Montana 1999 with Kreiger 1/10" twist. NXS 5.5-22x56 NP-R1.
    Hornady 225hpbt@ 2836fps seated .005" off the lands.
    WW brass, WLRM
    74.1gr H-1000.
    100 yd group @ .192moa x 5 rnds.
     
    #3
    Re: FFS & Shooter past 1K.

    The iPhone apps definitely have a falling off point as we noted...

    And G7 vs G1 makes no difference in my opinion, there is too much history and data to ignore and because FFS does not use Point Mass as its solver it is not depend on the curve that favors G7, which is why they use G1. There is much more readily available information for it, so it makes perfect sense. The history doesn't lie.

    I like the Apps for reference and for work inside 1000 yards, in a pinch, but they definitely fall off as you get further out. We noted BulletFlight lining up perfectly until you hit 1500 and then, as Greg noted it was a full Mil off.

    Behind the scenes I would venture to guess every iPhone App is 75% the same software, there are few variations but still, most use the same software to a degree to get to where they are going. No surprise they all fall off at roughly the same point. We may find it is glitch, and eventually they may fix it, but if you are serious about ELR an App is not the answer.
     
    #4
    Re: FFS & Shooter past 1K.

    I must say I was surprised when I did the calculation after I got FFS dialed in. I assumed that because Shooter could use G7 bc, & multiple bc it would be a more accurate prediction of point of impact. Oh well. I still like FFS for the better ranging, & multiple wind inputs. I also noted that shooter added a full moa above what was needed for wind too. Live, & learn. Still real happy with FFS, & my rifle.
     
    #5
    Re: FFS & Shooter past 1K.

    I wonder if this is a floating point precision issue within the APIs for the different platforms? Perhaps Android and iPhone OSs don't support the Double float but larger PDAs do? Without double floating point precision it's entirely possible that the errors are the result of rounding error at ELR distances.
     
    #6
    Re: FFS & Shooter past 1K.

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">.. but if you are serious about ELR an App is not the answer. </div></div>

    Amen, Commander!
     
    #7
    Re: FFS & Shooter past 1K.

    I am still curious why, with the computing power of a smart phone, an ap isnt as accurate as the software on a pda? I thought I had read, in the thread about the shooter ap, that it used the same solver as JBM.
     
    #8
    Re: FFS & Shooter past 1K.

    Apps are using a different Solving method, the engine to get the solution is based off Point Mass and software like FFS and ColdBore use an offshoot of Pesja which is not dependent on the drag model like Point Mass is...

    Get an App that doesn't run on Point Mass and we may have our answer, but then again, maybe not. However if you look at Wiki they say in the end as a period to the point:

    <span style="font-style: italic">The above example illustrates the central problem fixed drag curve models have. These models will only yield satisfactory accurate predictions as long as the projectile of interest has the same shape as the reference projectile or a shape that closely resembles the reference projectile. Any deviation from the reference projectile shape will result in less accurate predictions.</span>

    which is why Pesja for a computer in my opinion is better,

    <div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">The Pejsa model is an analytic closed-form solution that does not use any tables or fixed drag curves generated for standard-shaped projectiles. The Pejsa method uses the G1-based ballistic coefficient as published, and incorporates this in a Pejsa retardation coefficient function in order to model the retardation behaviour of the specific projectile. Since it effectively uses an analytic function (drag coefficient modelled as a function of the Mach number) in order to match the drag behaviour of the specific bullet the Pesja method does not need to rely on any prefixed assumption.[9]</div></div>
     
    #9
    Re: FFS & Shooter past 1K.

    Of course, the downside of the Pejsa system is the need to calculate the actual drag number, in FFS this is the DK. The default of .5 works very well for 'normal' bullets (as opposed to say VLD's), and even the specialty bullets track quite well inside say 1200m. After that, you'd do well to turne the system to the particular ammo being used.

    It's not really a terrible chore to tune the system, but it REQUIRES a fair degree of concentration and precision in the setup of the tuning shots, lest you find yourself chasing changes in BC, velocity and DK to track 'observed reality'. If the 'observed reality' is not ACTUAL reality, you can make yourself pretty crazy. I've pulled a few people out of some pretty deep holes they dug for themselves. for example, if you tell me the DK is .4, then you've done something VERY wrong, even though you are currently getting a very good elevation at this moment.

    The upside is this system, properly tuned, WILL give you as good a number as can be derived, and well within the capability of the operator/rifle. I can't say that about the other systems.
     
    #10
    Re: FFS & Shooter past 1K.

    You just described what I was going through before I just decided to start over with all the basics. I ended up clamping my rifle in a vice on a 3000# ecology block, & measured off 50yd to finally get my scope calibration done right. Then I chrony'd with 2 chronys, while double checking my zero to the gnats but. My DK now is in the .497 range. Before I started over I was constantly chasing dk, mv, & bc to get accurate dope.
     
    #11
    Re: FFS & Shooter past 1K.

    It can turn into a nasty feedback loop if you don't use some careful measuring. I find many people are either unwilling or unable to devote the effort to get the system properly calibrated. It is NOT very difficult, but it does require attention to detail. One day, perhaps two, a good chronograph and some targets at accurate ranges for zero range, close range (PBR zone), mid range, long range and trans-sonic range and less than 75 rounds will get it done.

    The big problem seems to be getting groups at longer ranges, then getting a good value for POA to center POI. Either the scope calibration was never done or is done wrong, or it's some kind of SWAG from impacts on a rock, etc. In an ideal world, you'd shoot a paper target at a known distance, although a clean steel plate with an aiming point/waterline will do. Ideally again, you'd put out a good group and then measure to POA from group center with a ruler. I'd like to get about 15 rounds out at 1200m and again at say 1500-1700m, that will pretty much pin it down.

    It's very good to shoot those groups over the chrono, so you have the actual average velocity for that group, rather than the 'average' you got during load development, which is sometimes 5 or 10 rounds and is hardly statistically relevent.
     
    #12
    Re: FFS & Shooter past 1K.

    Unfortunately I can't realistically set up steel, or paper tgts @ 1500+yd where I shoot elr but I can spot my own impacts, & use the np-r1 to get pretty close error estimates. I shoot @ the smallest rock I can clearly see to do this, & my last outing I was able to adjust the DK down too much the 1st time, & split the difference to get where I am now. Within 1 click. This weekend I'll be going back to my home range, & send some @ 1950yd to see how it continues to track.
     
    #13
    Re: FFS & Shooter past 1K.

    I've noticed the g7 is not quite the cats meow its made out to be. Case in point, the 2012 Cup. My first big match, had a blast. I used the Applied Ballistics app, almost identical to shooter. Using g1 for the curve and inputting values from the Kestrel it was SPOT on. Having had some issues with g7 in the past I plugged in the same set of environmentals and had it spit out a solution. It was quite a bit different. The g1 values were known to be correct because they worked. It was over 3-4 tenths of a mil difference if memory serves me. At 200 yards not a big deal, on d1 with all targets at or close to 1000 yards... It would be problematic.
     
    #14
    Re: FFS & Shooter past 1K.

    Never tried the G1 on the Shooter app. Always heard the G7 was the thing to use if you can. I'll try it next time.
    Btw my latest elr shoot was a blast. The FFS was still close enough that i couldn't tell if i needed to make any corrections. The wind was up, & we were shooting into the shadow side of a mountain, & we couldn't see any wind indicators out there at first. Found out that there was a significant updraft over there. I was being blown up almost 3 moa @ 1490yd. But as the day progressed the wind shifted, & the shadow left the mountain so we were able to make more accurate corrections. And FFS was still within a click or so but the wind was worth that much anyway.
     
    #15
    Re: FFS & Shooter past 1K.

    I used Exbal for 1200-2400 and the calculations were off inconsistantly under different weather/wind conditions every time. I switched to FFS 2 years ago and without tuning it I saw an immediate improvement in shot placement. After adjusted the DK to the load, it is always right where it should be.

    This is a big deal to me, I often shoot long range alone in Souther Arizona, I can spot my shots durring dry months but in late summer locating dust splashes beyond 2k while behind the rifle is difficult. I enjoy the challenge of contacting the target not chasing impacts. FFS has been the single best utility purchase for me.
     
    #17
    Re: FFS & Shooter past 1K.

    i have found the same as several posts here... Shooter is quite good for 308 and 338LM (here I am using Lapua's radar gathered G7 BCs) out to 800-900 for 308 and about 1200 or so for 338LM. But at the mile, Shooter just never gets the 338LM right. I'd have to check my notes for which direction it's off, but I am recalling that it predicted more drop than there actually was.

    All kinds of error in my Shooter input may abound though. My MV may have shifted somewhat. The way I have input the Lapua BCs into Shooter may not be what the Shooter developer would have done (the radar data provides several BCs based on velocity bands). And maybe these input errors don't matter much at mid range, but at longer range the ballistic model is more sensitive to input inaccuracies.
     
    #18
    Re: FFS & Shooter past 1K.

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">i have found the same as several posts here... Shooter is quite good for 308 and 338LM (here I am using Lapua's radar gathered G7 BCs) out to 800-900 for 308 and about 1200 or so for 338LM. But at the mile, Shooter just never gets the 338LM right. I'd have to check my notes for which direction it's off, but I am recalling that it predicted more drop than there actually was.

    All kinds of error in my Shooter input may abound though. My MV may have shifted somewhat. The way I have input the Lapua BCs into Shooter may not be what the Shooter developer would have done (the radar data provides several BCs based on velocity bands). And maybe these input errors don't matter much at mid range, but at longer range the ballistic model is more sensitive to input inaccuracies. </div></div>

    G1 or G7?
     
    #19
    Re: FFS & Shooter past 1K.

    G1 vs G7 example...

    Shot last week at 550 on the steel range.

    Alt 4545
    Temp 98
    Hum 10%
    Bar 25.10

    Values pulled from my Kestrel, G1 called for 3.4 mils elevation, it was dead on, made several hits on a Bigdog Steel head target, between the eyes on one. Punch in the same numbers with G7 and it calls for 3.0 mils. That's a difference of 7.92" with identical data. If I were shooting the prairie dog match at an moa size target I'd be low off the target.

    That's at 550 yards. Now imagine it was a competition at a distance of 800 or more. I will have to try this again as an experiment. I'll verify the mv with a chrono and maybe true the G7 value to see if it alters the mv from what the Chrono says.

    When I trued the G1 value I think the MV went from 2610 to 2608. I don't think that's the issue but I'd be interested to see how the truing tool resolves the discrepancy within the applied ballistics app.
     
    #21
    Re: FFS & Shooter past 1K.

    What ballistic software are you using? Also it looks like you have altitude, & station pressure going on there. You need to use only station pressure, & temp, or altitude, & barometric pressure corrected for sea level.
     
    #22
    Re: FFS & Shooter past 1K.

    Its the applied ballistics app, shooter with a few bells and whistles. I'm using altitude and barometric pressure, it's always been spot on. Having it just use the station pressure, without altitude, gives me a different solution that is close, but off in the other direction.

    I've had the best results plugging in the station pressure, uncorrected, from the Kestrel, AND altitude. That may go against the grain as far as the developers intent, but it got plenty of testing at the Cup and the solutions were dead nuts. I go with what works.

    If I have the time to use a ballistic calculator I plug everything in. Altitude, Temperature, Humidity, and Barometric Pressure (station, not corrected), and it gives me great results.
     
    #23
    Re: FFS & Shooter past 1K.

    Weird. The atmosphere data you posted would be in the eye of a hurricane at 4500'asl. But if it gives you good dope...
    I did some shooting today, & was going to try Shooter again, but the mirage was so bad I was having trouble just seeing the target against the backdrop. I know I hit when I heard the ding, just couldn't see it. May be cloudy next weekend so I might get some accurate shooting in then.
     
    #24
    Re: FFS & Shooter past 1K.

    If you put the Absolute Pressure / Station Pressure and also put in the Altitude you are doubling the air density so the computer thinks you are at 10,000ft and not 5000ft.

    It should not work, which is why most software (Apps) turn the altitude off when you use Station or Absolute Pressure.
     
    #25
    Re: FFS & Shooter past 1K.

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">If you put the Absolute Pressure / Station Pressure and also put in the Altitude you are doubling the air density so the computer thinks you are at 10,000ft and not 5000ft.

    It should not work, which is why most software (Apps) turn the altitude off when you use Station or Absolute Pressure. </div></div>

    Shooter and Applied Ballistics do shut off the altitude field when you check the box that says, station pressure.

    What I'm doing is punching in altitude, leaving that box unchecked (Meaning corrected pressure for sea level?) and punching in the station pressure number from the Kestrel, Reference altitude set to zero.

    Am I screwing something up or am I just terminology retarded and describing what I'm doing wrong?
     
    #26
    Re: FFS & Shooter past 1K.

    I went back and reread one of Frank's posts on the Kestrel. If I understand it correctly, setting the reference altitude to zero on the Kestrel gives you station barometric pressure at the unit, so it is uncorrected.

    The reference barometric pressure is set to 29.92 inHg, giving me a pretty close reading on current altitude.

    So why is entering the uncorrected barometric pressure from the unit, AND the altitude wrong? And why is it working so well?

    Edited to add that if I use the station pressure reading from the Kestrel, and I tick the box that says "Pressure Is Absolute" it shuts off the Altitude field so I can't put anything into it, and it altered the shooting solution by .2 of a mil. I would think it should have a bigger effect than that if I've been goofing this and doubling the air density all along?
     
    #29
    Re: FFS & Shooter past 1K.

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LawnMM</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cali_tz</div><div class="ubbcode-body">i have found the same as several posts here... Shooter is quite good for 308 and 338LM (here I am using Lapua's radar gathered G7 BCs) out to 800-900 for 308 and about 1200 or so for 338LM. But at the mile, Shooter just never gets the 338LM right. I'd have to check my notes for which direction it's off, but I am recalling that it predicted more drop than there actually was.

    All kinds of error in my Shooter input may abound though. My MV may have shifted somewhat. The way I have input the Lapua BCs into Shooter may not be what the Shooter developer would have done (the radar data provides several BCs based on velocity bands). And maybe these input errors don't matter much at mid range, but at longer range the ballistic model is more sensitive to input inaccuracies. </div></div>

    G1 or G7? </div></div>

    G7 for both 308 and 338LM. We shot 308 yesterday out to 900 yds and Shooter predictions were just about perfect.

    BTW, visiting Lapua's site for latest drag data and I found that they have a new ballistics app for Android:
    https://play.google.com/store/apps/detai...esult&hl=en

    Maybe this is old news for the hide. This is really cool since their previous mobile app was only for Windows phones. I am going to download this and check it out for sure. The advantage here could be that Lapua themselves input their radar drag data in correctly versus my guess for how to split the speed vs drag data into buckets for Shooter.
     
    #30
    Re: FFS & Shooter past 1K.

    550 is not very far, especially at 5000 ft above sea level, and you have a 3/4 MOA change there.

    I dont' know what to tell you, other than using the pressure the way you are, with the altitude included is wrong. If you find it works correctly for you, then stick with it I suppose. I dont see how it could work, but you say it does.

    When it gets cooler I wonder if it will continue to work as now it is hot so the DA is pretty high, which might be why ? But i am guessing.

    Bottom line, having Station Pressure and Altitude together is not the correct way to use the software... and the fact you find it works only shows the problem with App based software.
     
    #31
    Re: FFS & Shooter past 1K.

    I'll fix my screwup and do it right. I may keep an eye on it as the temps drop and see if the gap widens. It's not really the software's fault I was effin it up. It's giving a solution based on what I'm telling it. I suspect you are correct and because the DA is high and stable the answer is close enough for hits at distance. When the temps start swinging and the DA changes from morning to afternoon it may show its weakness.

    I was doing this at the Cup too and while I certainly wasn't a contender my misses had more to do with experience in awkward positions and my own lack of concentration. The splash was always where it needed to be on elevation.

    I'm going to do it the right way but I will try to investigate a bit as to why it's working the wrong way too.
     
    #32
    Re: FFS & Shooter past 1K.

    quick review on the Lapua ballistics Android app... it's pretty meager feature set wise. One problem or interesting limitation is that the app does not calculate any solution for which the bullet speed is sub-sonic. That could be because Lapua figured sub-sonic transition is too unpredictable to suggest a solution.

    Also it does not give you tables... you can only enter one range, and get one scope solution. For roughly same set of inputs, Shooter gave me 19.5 mil up for 1700 yards, and Lapua app gave me 19.3 mil up. At 1760 Lapua said I was subsonic, and Shooter said I wasn't subsonic until past 1800 yards.

    However, if Lapua is more accurate up until that subsonic point it could be useful. Will try this in the field when our BLM mile range opens up next month.
     
    #33
    Re: FFS & Shooter past 1K.

    It really is too bad that FFS wouldn't offer an android version of the software, as most smart phones are 10x as capable as most PDA's running FFS. I find it much more convenient as a weekend warrior to use a cell based solution as opposed to a dedicated PDA because when I was using a PDA I would always forget to charge it resulting in a dead battery when I needed it.
     
    #34
    Re: FFS & Shooter past 1K.

    I actually like the pda. I got one for about $50 off e bay, so if I break it I'm only out $50 instead of $500 if I drop it in the water, or step on it. But I have wondered if ffs would load on my android. I bet it won't because the mobile os is different.
     
    #36
    Re: FFS & Shooter past 1K.

    The software is great from what I've heard, the problem is the platform is long in the tooth. A trimble pda runs what 800-1200 new? My phone has a dual core 1.5ghz processor and 2gigs of ram. It runs like 650 off contract. Phones have the horsepower but the ballistic software people aren't tapping into it yet.

    I'd love to see FFS running on a quick phone running windows 8 in the future. Slap a heavy duty case on a phone that isn't your daily driver and you have a pretty capable device with bluetooth, gps, wifi, nfc, etc. For now all you can run on them is the app based ballistics and as Lowlight has mentioned, the method used is different and loses accuracy out around 1500
     
    You must log in or register to reply here.

    Similar threads

    T
    M14 with Lothar-Walther heavy profile 6.5 Creedmoor barrel testing (ongoing)
    Replies
    4
    Views
    457
    Red_Foreman
    R
    E
    My redneck SPR story
    Replies
    26
    Views
    712
    ut755ln
    ut755ln
    BoltBandit
    Trouble Shoot Sudden POI Drop
    Replies
    10
    Views
    388
    Slides
    Slides
    F
    2024 TENET Midnight Madness Night Run and Gun. My Journey to The Finish Line.
    Replies
    17
    Views
    784
    Burdy
    Burdy
    C
    ABMobile True Up
    Replies
    7
    Views
    335
    Rio Precision Gunworks
    Rio Precision Gunworks
    Top Bottom
    Back
    Home
    Forums
    Merch
    Alerts