JBM calculator

[Krakkon]

Has anyone used the JBM calculator in MOA with a 1/8 turret? Am I correct by assuming that I would put 0.5 in the drop units chart for 1/8 clicks?

I have seen mention of using .125 for 1/8 clicks but that seems crazy for spinning turrets..

Please help a noob! thanks guys..

 

[loadedround]

I've been shooting for over 45 years and now l assume that technology has finally passed me by. I have never heard of a JBM calculator and would like to know what it is.

 

[freakshow10mm]

It's an online ballistic calculator website.

 

[rcmodel]

1/8" clicks are .125".

0.5" is .500".

I didn't know what the JBM Calculator was either.

But I know 1/8" is .125".
And that is what you would have to use in the calculator program to match your scope adjustments.

rc

 

[Krakkon]

Hmmm... something is all outta whack
Shooting my 300 Ultra mag using a 210 berger @ 3000 fps and MOA drop units at .125 it shows a -53.0 at 600 yards with a 300 yard zero!

That would hit extremely high.. :banghead:

http://www.eskimo.com/~jbm/cgi-bin/jbmcard-5.0.cgi

 

[~z]

I would believe 53 clicks (@1/8 MOA each) but surely not 53 MOA, you should not drop but 40-45" at that range
~z

 

[rcmodel]

O.K.

I just went and looked at the JBM Calculator.

It asks nothing at all about your scope click value that I can see.

All it asks is if you want your Windage & Drop displayed in MIL, MOA, In, or Cm.

If you put 1" Inch units, take what it says the drop is and multiply it by 8 to get how many clicks your scope adjustment would need to be.

rc

 

[Krakkon]

So in order to make a printable drop chart with 1/8 clicks the value would be?
maybe im making this alot more complicated than it really is..
I have a 1/4 turret on my AR and using the default 1.0 seems to work
that is why i had questioned using .5 for 1/8 turrets

I do appreciate the feedback guys, thanks again..

 

[rcmodel]

1 click is 1/8 inch at 100 yards.
1/4 inch at 200 yards
3/8 inch at 300 yards.
1/2 inch at 400 yards.
Etc, etc, etc,.

Say you have a 200 yard zero.
And the drop is 20" at 400 yards.

You would need 40 clicks to raise the POI to zero at 400 yards.

rc