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:

  Imperial Metric
Altitude: 2490 feet 758 metres
Temperature: 47 F 8 C
Air Pressure: 27.07899 inHg 917 mb

Humidity: 77%

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:

  Imperial Metric
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:

BC Model Value
G1 0.351
G7 0.176