After an amateur attempt at trying to calculate the BC of the Norinco 7.62x39mm ammunition, I thought I would do the same thing with Norinco’s 7.62x51mm ammo. As one would expect, this stuff is fairly inexpensive as well, running aroun $0.50/round. I don’t think this is “precision ammo”, but it works well enough in my M-305 rifle.
First off, I pulled one bullet apart, and weight it. The projecticle itself weight 146.1 grains, so I guess this is supposed to be 147gr ammo. I measured ~ 42.0 grains of “mystery gun powder”.
First some environmental data that I recorded while I was at the range (or looked up on Google Maps) earlier this week:
|Altitude:||2490 feet||758 metres|
|Temperature:||47 F||8 C|
|Air Pressure:||27.07899 inHg||917 mb|
Next, after firing 19 (well, it was 20, but only 19 shots were recorded by my chronograph) rounds through my M-305, I collected the following information:
|Average Velocity:||2670 fps||814 m/s|
|Highest Velocity:||2731 fps||832 m/s|
|Lowest Velocity:||2621 fps||799 m/s|
|Extreme Spread:||109 fps||33.1 m/s|
|Std. Dev:||27 fps||8.34 m/s|
I’ll omit the velocities from the flight of the bullet, we’ve got enough boring numbers. So running these numbers through the JBM BC calculator and we get the following two BC values: