PDA

View Full Version : I have seen the JBM light!


wildcard
12-08-2007, 1:38 PM
Well I finally decided to bust out my cronograph and punch in all my data into a JBM calculator to see how it compares to my actual data. That thing was right on (+/- .25 MOA)! Well at least up to 600 yds since I haven't gotten data for anything past that in its new setup.

Prc329
12-08-2007, 1:51 PM
JBM has always been very reliable. So has the nightforce software. Even though I choked at the match I got my dope for the buffalo at 865 with it.

rksimple
12-08-2007, 1:55 PM
It usually works pretty well. Its imperative that all the conditions are accurately entered. Up here where temperature swings can be extreme, it can change things quite a bit.

wildcard
12-08-2007, 1:55 PM
Actually.. it seems to match perfectly only if I make elevation 0 and my objective height 1.5. Incorrect inputs.. but the outputs are perfect :)

rksimple
12-08-2007, 2:46 PM
Actually.. it seems to match perfectly only if I make elevation 0 and my objective height 1.5. Incorrect inputs.. but the outputs are perfect :)

At what elevation were you shooting? If incorrect input yielded correct output, correct input may be incorrect.

PistolPete75
12-09-2007, 3:36 PM
Actually.. it seems to match perfectly only if I make elevation 0 and my objective height 1.5. Incorrect inputs.. but the outputs are perfect :)

yep, same issue for me with jbm. i have to play around with the objective height too.

Vu 308
12-09-2007, 6:16 PM
I find that JBM...along with most ballistic programs to be within .25 to .5MOA out to 600yards and then within 1MOA out to 1K.