Comments on: Ballistic Software Comparison: Nightforce Exbal vs Lex Talus Delta IV

By: Steven

Steven — Wed, 21 Jul 2010 17:29:58 +0000

Hi everyone I just want to know is there any books to learn everything there is to know about longrange shooting as im thinking about doing some long range hunting and target shooting?

By: Lucas

Lucas — Fri, 04 Dec 2009 07:03:44 +0000

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.

By: Glen Roberts

Glen Roberts — Fri, 04 Dec 2009 04:07:58 +0000

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 Blaineâ€™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 mathâ€™s code to predict trajectories, some conservative and some not. It doesnâ€™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 itâ€™s high fives all round.

Great to see your work being done.

Regards

Glen
LongRangeHunting.com.au

By: Sean Pomerinke

Wed, 02 Dec 2009 05:52:01 +0000

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

By: Chopaka81

Chopaka81 — Sat, 28 Nov 2009 07:29:28 +0000

Very interesting read Lucas. Nice work. Don

By: Lucas

Lucas — Sat, 21 Nov 2009 06:10:08 +0000

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.

By: Ryan Berg

Ryan Berg — Fri, 20 Nov 2009 06:41:28 +0000

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