Need the BC of .30 caliber JSB/FX 44.75 and 55.50 gr

[kaylaindy]

Hey guys, I'm trying to program my PARD and I need the BC of any one of these 4 pellets.

FX .30 cal 44.8gr (pellet of choice)
FX .30 cal 50.2gr

JSB .30 cal 44.75gr
JSB .30 cal 51.50gr

Thank you! -Nate

 

[Kgphotos]

Hi Nate,
With your chronograph you can determine a very accurate BC. It is a great method as you will determine the correct BC for your elevation, your particular barrel, weather … Don’t forget that BC is a constantly changing number. Anyway, just use your chronograph to determine the muzzle velocity (use a 10 shot average) and then do it again for an accurately measured distance down range. Now, with those two measurements you can use StrelokPro or ChairGun and they have tool to calculate BC. You can even plot it with three or four down range distances and see how BC changes with distance and velocity.
Kenny

 

[kaylaindy]

Kenny, Thank you..as I will have to explain the exact thing in my video. Great explanation of how to calculate that. I did not know for sure how it was done.

....Hard Air Magazine has alot of the common pellet's BC stats here: https://hardairmagazine.com/ballistic-coefficients/

I found the JSB...does anyone know the FX?

 

[Centercut]

Kenny, Thank you..as I will have to explain the exact thing in my video. Great explanation of how to calculate that. I did not know for sure how it was done.

....Hard Air Magazine has alot of the common pellet's BC stats here: https://hardairmagazine.com/ballistic-coefficients/

I found the JSB...does anyone know the FX?

View attachment 324571

Both those are wrong. The 44.75 is about 0.043. The 50.1 is about 0.047. I have verified this with a .30 FX Bobcat and a .30 Daystate Delta Wolf. FX are same as JSB.

 

[Bill_D]

Strelock app confirms approx the same - 44.75 = 0.042, 50.1 -= 0.047
"Both those are wrong. The 44.75 is about 0.043. The 50.1 is about 0.047. I have verified this with a .30 FX Bobcat and a .30 Daystate Delta Wolf. FX are same as JSB."

 

[Kgphotos]

There are so many variables involved with calculating a BC that it is difficult to just ask someone what it is. BC is not a set number and it will constantly change. I live at an elevation of 357 feet. In the summer I often camp and shoot at 8500 feet. The difference in the BC of my projectiles changes a lot. So much so that I have two different drop charts to use. Weather, temperature, altitude, humidity, your barrel twist rate, maybe even the color of your socks all influence the BC. If you use velocity change to calculate BC (which is what I do) and you chronograph at muzzle, 25 yards, 50 yards and 75 yards you will see that the BC even changes along the flight path of a single pellet or slug.

 

[kaylaindy]

Hey, Thanks for the correction! I still have yet to enter my data..so I will use the correct #'s. Thanks for the help! -Nate