Range Report JBM Ballestics filed Tactical ediition

Arif

Sergeant
Full Member
Minuteman
Sep 26, 2009
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Hi Guys, I need your help with the JBM Filed Tactical edition which I got for my i phone.

I have a 338 Lapua Magnum and the Lapua company only provides G1 BC coefficient of .675 for 250 grain. When I input data in the program I use .675 as native drag model but then I ask the program to use the G7 drag model. Is that ok or should I be suing G7 in both or stay with G1.
 
Second question is that the program gives me a G7 BC of 334 for the 338 Lapua Magnum 250 grain Scenars velocity 2970 . when I compare it to the G7 BC provided by another application e.g I snipe which gives me a BC of .322for the same bullet which is different then JBM which gives a BC of .334.
I would apprecite if you can please explain why the difference.
I have sent thse questions to teh author of the program as well but not sure if he has the time to respond.

Thank you in adavance for your comments
AJ
 
Re: JBM Ballestics filed Tactical ediition

Just to clarify, do you mean you are using Ballistic - with the JBM engine selected? What I would do is use the web version of JBM and compare your results with that. I don't think Ballistic includes the Litz G7 BCs. So use web JBM first and see what you get, then using the same parameters otherwise, change the G7 BC in Ballistic until the results match the output from the web JBM.

The reason you'll have to do this is because JBM does not show Litz's BCs (otherwise people might not buy his excellent book - Applied Ballistics... - which you may want to have anyway). Heck, get a copy of the book and grab the BCs from there. You'll learn a lot of useful things about long range shooting.
 
Re: JBM Ballestics filed Tactical ediition

Here's the issues I've discovered with FTE in regards to the G7 bullet library. I purchased this program for my iPhone because it stated it had Bryan's G7 bullets in its library which it does. Once I figured out the program was not written by Brad at JBM I reverse engineered a couple calculations to make sure it was running the actual JBM ballistic models which it is.

Next I searched my butt off to find Bryan's list of G7 BC's which are in the program but are not listed. That's not very user friendly. The user interface on this program is quite good but when it comes to a bullet library it "SUCKS" and sucks bigtime!

In the "Trajectory" menu which is very good and very straight forward for all of your inputs you can change the Native Drag Model from G1 to G7 which changes the "Use Drag Model" selection to G7. This is great however it doesn't change the G1 listed BC. So you’re left wondering if the change actually took place. When you run the "Calculate Trajectory" the calculated "Input Parameters" actually show the new G7 BC.

Again this is great but what G7 BC is being used????? Is it from Bryan's G7 library or a recalculated bullet manufactures G1 BC? The answer is both! Back to this "SUCKS" big time. Again nowhere in the bullet library is a list of G7 BC's for any of the bullets.

I sent a couple emails to the programs creator Jonathan Zdziarski to get answers to my questions. Jonathan replied to my first email but side stepped my questions on the G7 library saying it was only for military bullets. I replied and asked which military bullets as well as few other questions? Jonathan has yet to reply to any of my other emails and has blown me off for over a month. His customer support is poor at best.

I talked with Bryan Litz yesterday and Bryan informed me he had zero input on this program and really knows nothing about it since he doesn’t have an iPhone but uses a Droid.

Yesterday I purchased Knights Armament Bullet Flight ballistic program…hey what’s another $29.00. This program is OK at best and like the JBM FTE and has some really cool features. It has a very good advertised bullet library and lists Bryan’s bullets but does not show the actual BC (this sucks bigtime again). On top of that the bullet library is someone difficult to find and you have traverse multiple menus to find the bullet you want and to make your change. Changing your bullet to another bullet is really screwy and not straight forward at all. Actually when you select the bullet from the ballistic library absolutely nothing happens except a pop up Notice “BC Value selected. Modify or create a profile where all you get is a Press OK. Then you press OK and it takes you back to the bullet library menu where you have to back out of the menus back to the main screen to run your calculations.

Once you do run the "Range Card", "Calculate Ballistics" or Calculate Simple", nowhere in any of the output data fields does it tell you what bullet you're shooting, the Coefficient Drag model let alone the bullets BC. This "SUCKs" big time and is standard on every ballistic program I own...which is too many to mention. I'm left wondering what the heck am I calculating????? BTW the "Calculate Simple" is a really cool tool.

This program also has some very limited output functions and doesn't let you customize your ballistic output data very much or very easily. Again simple tools most ballistic programs offer. Overall I find this program average to below average at best with a couple very cool tools. Actually the more I play with this program the more disappointed I am with it after hearing all the great hype about it. It has great potential but needs a lot of work on user interface. I mean a lot of work. The UI is really bad and I'm betting most users don't realize their output may not be what they're are actually inputting. Because the program doesn't show you bullet, drag model and BC I found myself making changes but running standard profiles.

Overall the JBM FTE is the best of the two programs as the setups are way easier, much faster and much more straight forward, plus I can customize my output data fields very easily. Fix the bullet library and add a "Calculate Simple" display like Bullet Flight and you have an outstanding program.

So there you have it. Hope it helps!