Next up for the Big Freakin’ Cartridge Test is Vympel’s budget 55gr FMJ load in .223 Remington, made in Amursk, Russia. This ammunition features a lacquered steel case, bimetal jacketed 55gr FMJ bullet and purple neck sealant. This is one of my favorite practice rounds due to its environmental toughness. Continuing on from the last installment, we are now looking at the velocity test results for the 20″ barrel (more on the 16″ later). The test procedure was as follows:
- Condition ammunition to 70 °F +/- 5 degrees for at least 1 hr (in practice ammunition was always conditioned overnight).
- Mount chronograph to barrel or rail.
- Record the temperature in the conditioned container before each string.
- Withdraw one round of ammunition from the cooler.
- Load and immediately fire the round.
- Cool chamber back to ambient conditions for 30 seconds*
- Repeat steps 3 through 6 nine more times.
This procedure was followed for 14.5″, 16.1″, and 20″ barrel length velocity tests. To measure velocity, a Magnetospeed V3 chronograph was used attached to the barrels of the 16.1″ and 20″ uppers, and the rail of the 14.5″ upper. It needs to be noted that for all 16″ barrel testing, a cooling time of 10 seconds was used instead of 30, as it was becoming obvious that the additional 20 seconds were unnecessary. In the future, 10 seconds will be used for all barrel lengths.
The chronograph results for the 20″ FN chrome-lined CHF barrel are as follows (Shot #, followed by muzzle velocity in ft/s):
Which gave us the following figures:
Min: 3,113 ft/s
Standard Deviation: 19.2
Extreme Spread (highest minus lowest): 55
Normally at this point, we would also look at the chronograph results for the 16.1″ Colt chrome-lined cut rifled barrel, but unfortunately, those readings do not exist for this round as the Magnetospeed V3 chronograph failed to read the steel-jacketed Golden Tiger projectiles from that barrel length for some reason. Diagnosis of this problem will have to wait until after the 2018 SHOT Show, sadly, but I do intend to revisit the round.
Even here with the relatively inaccurate and inconsistent Golden Tiger ammunition, we still see a tightening of velocities when moving from the 14.5″ to 20″ barrel – in fact, the extreme spread from the 20″ barrel was less than half that produced by the 14.5!