Product Review

Ballistic Software Comparison: Nightforce Exbal vs Lex Talus Delta IV

By ⋅ November 16, 2009 ⋅ Post a comment

The key to shooting long range with accuracy is knowing and compensating for ballistics. Ballistics programs allow you to input your specific load information (most importantly bullet ballistic coefficient and muzzle velocity) and atmospheric conditions and then, provide you with a predicted flight path. Any experienced long range marksman will know that these predictions are often very close at closer ranges (usually out to about 500yds) and usually not so close at longer ranges. Ballistic coefficients are speed dependant because they are based off a given profile, the G1 profile being the most common. If your bullet were a perfect match to the G1 profile your BC would remain the same despite the velocity. The variance with speed is so great because the G1 profile is nothing close to the profile of long range low-drag, boat-tail, bullets most popular today. The problem is well known and the better ballistic programs have compensated for this issue to some degree.

I have been using the Nightforce Exbal program for some time and I’m very happy with it. It has allowed me to make a few cold-bore shots at extreme distances that I wouldn’t otherwise be capable. I can get information on how changing atmospheric conditions will effect my dope (data on previous engagement). I have this program loaded into a palm pilot that I can use in the field (although I’m never without a written drop chart for obvious reasons). Other features include trajectory validation, point blank range analysis, target engagement, factory load data, bullet BC data, reticle analysis, scope adjustment options, target distance estimation, etc. It’s safe to say I’ve got my money’s worth from the Exbal program. With such a comprehensive program you might wonder how Exbal compensates for inaccuracies of BC’s changing  with speed. They have included a multi-BC option where one can enter 5 different BC’s at 4 specific velocities (last velocity value must be at zero). This allows you to tailor your BC to match your confirmed drops in the field. Sierra Bullets provides multiple BC’s and using these will allow you to get very good data from the program right from the start. Unfortunately most bullet manufacturers don’t give multiple speed dependant BC’s. Obviously bullet BC’s don’t change suddenly at a specific velocity, so multiple BC’s isn’t a perfect fix, simply a compromise. Even so, I’ve found it possible to get an essentially perfect drop chart using the multiple BC option. When using bullets without published speed dependant BC’s you’ll be spending some time playing with the program to get your drop chart just right. It usually takes more than one long range shooting session to get everything just right.

Thanks to Sean (host of longrangeshooter.com) I recently had the opportunity to test the Lex Talus Delta IV ballistic program. Completely satisfied and very familiar with Exbal, I was honestly expecting just another ballistic program. It doesn’t take long to notice a difference when inputting basic data. When using standard G1 BC’s you will get drop charts much closer to actual numbers than with other ballistic programs. This is due to the type of compensation Delta IV uses for BC variation with velocity. They label it “DK” which is a way of calibrating BC degradation and they also claim it can be used to compensate for shooter to shooter variances in launch dynamics. I must say that the default DK settings gives me very close drop info compared with my confirmed data. I’ve found that adjusting the DK (and BC if  advertised BC is off)  is easier to get “perfect” drops compared with the adjustment of multiple BC’s and the velocities at which those BC’s “change”. Delta IV includes all of the options of the Exbal program mentioned above. One option of Delta missing with Exbal is the powder temperature (ammo temp). You can adjust how sensitive your powder is to temperature. I gravitate to using powders that are not particularly sensitive to temperature. I have a reasonably wide range of temperatures where my drop charts will allow hits on reasonably small targets, but there’s no getting around changes in MV due to temperature. In one competition a couple years ago, the temperature rose to over 100 degrees and I quickly discovered I was missing high. My “temperature insensitive” loads had lulled me into a false sense of security. If only I had been using Delta IV back then! Having this option will allow you to get very accurate drops even when out of your normal temperature range.

To compare these programs I did a few tests. I have some confirmed drops for a couple different rifles. I decided to input “standard” BC info (only data that’s readily available), no multiple BC’s except for Sierra bullets. I only used the default DK for Delta IV. Either program can be adjusted to match your tested drops. Obviously, I made all the elevation, atmospheric/scope height data the same. I think  these examples  give a good basic idea of the program capabilities. Before I get into all the specifics let me just say that there are numerous reasons this test isn’t a perfect comparison including: operator error (in using the programs and/or shooting the rifles) imperfections in my confirmed drops, difference in actual MV and measured MV, error in atmospheric condition and elevation data, group dispersion, scope calibration error (I check mine but when you dial over 50 MOA a small error will show up in drop chart data), bullet manufacturer BC inaccuracy, etc.

Test 1) 7wsm 168gr JLK @ 2910fps Advertised BC .690

500yds Actual drop 8.25 MOA                                     1000yds Actual drop 24.50 MOA

500yds Exbal projected drop 8.00 MOA       1000yds Exbal projected drop 23.25

500yds Delta projected drop 8.25 MOA           1000yds Delta projected drop 24.25

This test was not exactly fair to either program since the advertised BC of this JLK bullet is too high in my opinion. Delta was still very close!

Test 2) 243 win 108gr Berger BT @ 2912… Advertised BC .511

500yds Actual Drop 8.50 MOA                   1000yds Actual Drop 27.75

500yds Exbal projected drop 8.50      1000yds Exbal projected drop 27.00

500yds Delta projected drop 8.50       1000yds Delta projected drop 28.25

Test 3) 308 win 175gr SMK @ 2729… Advertised BC’s .505 (2800fps+) .496 (1800-2800fps) .485 (1800fps-)

500yds Actual Drop 10.25 MOA                                     1000yds Actual Drop 32.75

500yds Exbal projected drop 10.00 MOA       1000yds Exbal projected drop 32.00 MOA

500yds Delta projected drop 10.75                           1000yds Delta projected drop 34.00 M0A

This test illustrates how the Exbal program works with multiple BC’s.

Test 4) 338 Lapua Mag 245gr Bore Tech V3 @ 2895… Advertised BC .869

500yds Actual Drop 7.25 MOA                 1000yds Actual Drop 22.00

500yds Exbal projected drop 7.25    1000yds Exbal projected drop 21.50

500yds Delta projected drop 7.25       1000yds  Delta projected drop 21.75

1850yds Actual Drop 58.00

1850yds Exbal projected drop 59.00

1850yds Delta IV projected drop 57.75

This one is truly amazing. Delta was within ¼ MOA at over a mile! I wouldn’t have imagined this was possible. Now the info after using Delta IV’s DK calculating option which gives me a new DK of .4992 new drop info was

500yds 7.25 MOA

1000yds 22.00 MOA

1850yds 58.00 MOA

A quick and simple step (DK calculation) gives me an essentially perfect drop chart not just at 500yds (most on-line ballistic calculators could do that) but spot on at 1000yds and 1850yds! To say that I’m impressed with Delta IV would be an understatement.

Lucas Beitner

Discussion

  • Ryan Berg

    Nice write up Lucas! I like the ‘confirmed drop’ functionality – something missing from Exbal. As we all know, every rifle’s different and the BC models, however accurate, don’t account for that, but being able to input a confirmed drop for a given distance and have it compensate and churn out a corrected drop chart is slick! Makes me want to upgrade my phone 😀

    Ryan

  • Lucas

    Thanks Ryan. I believe Delta’s drop confirmation is superior because it’s changing the correct variable (bullet BC variation). Exbal’s trajectory validation changes MV, and they don’t allow it past 1000yds (probably since it would recommend way too slow a MV beyond that distance). There may be another factor that Exbal changes because I notice that my shooting partner’s Exbal gives different results than mine with the same inputs and he uses the trajectory validation often and I don’t.

  • http://http://http://http:// Chopaka81

    Very interesting read Lucas. Nice work. Don

  • http://longrangeshooter.com Sean Pomerinke

    I love the software
    It is being taught to our military as we speak

  • http://www.longrangehunting.com.au Glen Roberts

    Nice work Lucas. Very glad to see the last 5 lines written in paragraph four. There are always errors and as Bryan Litz explains in his book “Applied Ballistics for Long Range Shooting” some of these errors are easy to reduce and some are very difficult.

    This sport of long range shooting is all about reducing the errors. I have been a user of Field Firing Solutions Software for some time now and the results do speak for themselves. It is fantastic.

    Ammunition temperature or Powder Burning Rate is a big one. To discount this in software development is simply being egotistical. Going back to the errors, ascertaining exact velocity is in fact very difficult. How precise is the chronograph, when was it calibrated and what was it calibrated against. Exact G1 BC’s are also very difficult to get, especially if there is a question mark on the velocity in the first place.

    G1 BC’s are velocity dependent however they are also dependant on air density which is related to the Mach number at that specific air density. A change in air density (Altitude, temp etc), changes the G1 BC value at any given “DISTANCE” because the velocity at that distance has also changed.

    It starts to get complicated. So Ballistics programs that rely on “G1 BC Barriers) are better than the old Sierra Ballistics DOS programs of the 80’s but they are far from perfect. Even though Blaine’s programs still use the G1 BC, they in effect “assign” a brand new BC for that particular projectile out of that gun.

    Adjusting the DK, although a good feature should only be done as a last resort. This DK value as explained by Arthur Pesja in his books as the “N” Value or “1/F” is a remarkable piece of mathematics. Messing with this value when only using supplied BC’s from manufactures can cause problems.

    I have found altering the G1 BC a little and leaving the DK of 0.5 works a treat. I calibrated the Sierra 175gn Matchking right out to 1320m fired out of a .308Win cartridge. I went out on a limb and altered the G1 BC to 0.515 leaving the DK at 0.5. Not only did these projectiles hit every mark but on 5 different occasions (days), distances, altitudes and temperatures. But this was for my gun.

    What I am saying to users is that the G1 BC values we get, have up to a 10% error from the manufacturer. Also with this, every ballistics program will use different math’s code to predict trajectories, some conservative and some not. It doesn’t really matter to some extent what BC values we put in (within reason), so long as what we get out the other side is very close to what actually happening between your muzzle and the target.

    The real test of these programs is repeatability day after day at different altitudes and temperatures at different distances. Get within 0.1 Milrad or 1/4 MOA of your target and it’s high fives all round.

    Great to see your work being done.

    Regards

    Glen
    LongRangeHunting.com.au

  • http://http://shoot-farther.com Lucas

    Thanks for sharing your advise/experience Glen! I think Bryan Litz elimenates more variables than I do… but I’m working on it. I think many rely too much on ballistic programs, trusting the data to be close enough which it may or may not be. It is encouraging seeing the improvments in the technology.