Friday, November 04, 2016

Power Factor

I was asked recently, what is the power factor of the ammo we use in Cowboy Fast Draw.  I had to admit that I didn't know.  But, power factor is a well-used terminology in the shooting sports, and while there are several methods of calculating it, the most common is represented in this equation.

Power Factor = Bullet Weight X Velocity / 1000

As we all know, in IPSC, we have to have a minimum power factor of 170 to "make major" and a minimum power factor of 125 to compete.  Various charts abound, but this one comes up quickly on search engines.

I went out this morning early and with a standard wax bullet and weighed it on my well-used Hornady scale.  My particular wax bullet weighed in at 18 grains.  The velocity data was taken last summer in my backyard.  So, a quick-and-dirty power factor on my ammo would look like this:

Power Factor = 18 X 729 / 1000

Plugging the numbers into my calculator gives me this:

Power Factor = 13.122

Now, we know.


Old NFO said...

Interesting... But a helluva good safety factor! :-)

Bradley said...

Thanks for the info, I knew it at one time but forgot, i shot my last IDPA match with a S&W 58 in 41MAG, its power factor was more than enough for major, and was very effective on steel. 180grn @ 1350ishFPS=243 PF.

Damn that was a fun match.