Ballistic data

.224 55gr FMJ boat-tail

Updated 19 October 2026

G7 0.135Ballistic coefficient (primary)

G1 0.271Equivalent G1 ballistic coefficient

1015 m/sMuzzle velocity, 600 mm test barrel (3330 fps)

55 gr3.56 g · .224" (5.56 mm) · boat-tail

Summary
Source data
How we calculated it
Checks
Using the BC
Caveats

Summary

The Lead & Copper .224 55gr FMJ boat-tail has a ballistic coefficient of G7 0.135 (G1 equivalent 0.271), back-calculated from our own test data. The testing was carried out by an independent third party to ensure impartial results.

Bullet	.224" (5.56 mm), 55 gr (3.56 g), full metal jacket, boat-tail
BC, G7 (primary)	0.135
BC, G1 (equivalent)	0.271
Valid velocity band	about 1015 to 485 m/s (0 to 500 m)
Atmosphere basis	ICAO standard, sea level: 15 °C, 1013.25 hPa
Test barrel	C.I.P. test barrel, 600 mm, 1:9" twist
.223 Rem max. pressure	4300 bar (C.I.P. P_max)
.223 Rem typical muzzle velocity	about 1000 m/s (3280 fps)

G7 is the primary figure because it is the drag model made for boat-tail rifle bullets, and it held within about ±3% across the whole 0–500 m range. Use G1 0.271 if your app or reloading manual only takes G1.

Source data

All figures come from our "Ballistic Properties" test, carried out by an independent third-party test facility to keep the results impartial. They are average values from a C.I.P. test barrel, 600 mm, 1:9" twist. Muzzle velocity is 1015 ± 15 m/s, with a maximum standard deviation of 12.0 m/s.

Range (m)	Velocity (m/s)	Velocity (fps)	Bullet path (cm)	Energy (J)
0	1015	3330	–	1835
100	890	2920	0	1410
200	775	2543	−12	1075
300	670	2198	−41	800
400	575	1886	−92	585
500	485	1591	−173	425

Bullet path is measured from the bore line with a 100 m zero. The fps column is our conversion (1 m/s = 3.281 fps).

How we calculated it

A ballistic coefficient (BC) says how well a bullet keeps its speed compared with a standard reference projectile. G1 is the old flat-base reference shape; G7 is a long boat-tail shape, much closer to this bullet. A higher BC means the bullet slows down less.

1. The drag model

The bullet's slow-down at any speed is the reference drag for that speed, scaled by the BC and the air density:

dv/dt = − (ρ / ρ₀) · Cd_ref(Mach) · v² · k / BC ρ / ρ₀ air density relative to the standard (1 at ICAO sea level) Cd_ref(Mach) drag of the G1 or G7 reference shape at that Mach number v bullet speed k a constant that fixes the units BC the number we are solving for (lb/in²)

We solve this step by step along the flight path, with gravity acting on the bullet too (a standard point-mass trajectory). It is the same method ballistic apps use.

2. Fitting the BC

Start the bullet at 1015 m/s in the ICAO standard atmosphere (15 °C, 1013.25 hPa, sea level).
Pick a trial BC and fly the bullet out to 500 m, noting its speed every 100 m.
Compare those speeds with the table, and adjust the BC until the total error across 100–500 m is smallest.
Do this once with the G1 reference shape and once with G7.

The best fits are G1 0.271 and G7 0.135.

3. Model against the table

Range (m)	Table (m/s)	G1 0.271 (m/s)	G7 0.135 (m/s)	Table path (cm)	G1 0.271 path (cm)
0	1015	1015.0	1015.0	–	0.0
100	890	889.7	892.8	0	0.0
200	775	775.4	777.7	−12	−12.5
300	670	670.1	671.2	−41	−41.4
400	575	573.4	573.6	−92	−92.4
500	485	486.4	483.4	−173	−173.5

Model run: ICAO standard atmosphere, 1015 m/s, sight height 0 (bore line), zeroed at 100 m, 1:9" twist.

Consistency checks

The three rows of the test table agree with each other, which supports using them for the BC.

Bullet weight, from the energy row

E = ½ · m · v² → m = 2E / v² m = 2 × 1835 J / (1015 m/s)² = 0.003562 kg = 3.56 g = 55.0 gr

✓ Matches the stated 55 gr bullet.

Velocities

✓ One G1 BC of 0.271 reproduces every listed velocity to within 1.6 m/s.

That is inside the table's rounding to the nearest 5 m/s. G7 0.135 stays within 3 m/s.

Bullet path

✓ The same G1 0.271 reproduces the drop row to within 0.5 cm.

That assumes a sight height of 0, so the path is measured from the bore line, zeroed at 100 m. With a scope 40–65 mm above the bore, real drops past 100 m are smaller than the table shows.

Using the BC

The BC is a property of the bullet, not the load. It applies at any muzzle velocity and from any barrel, provided the bullet is stable.
Enter the BC unchanged, then set your real altitude, temperature and pressure in the ballistic app. At Pretoria (about 1350 m) the air is roughly 15% thinner than at sea level, so the bullet sheds speed more slowly than the table shows.
Use your own muzzle velocity. A typical .223 Rem load runs about 1000 m/s; chronograph yours, as shorter barrels and lighter charges will be slower.
Twist: a 1:9" barrel stabilises this 55 gr boat-tail fully. A poorly stabilised bullet shows a lower effective BC.

Caveats

The BC is back-calculated, not measured directly. It is fitted to the velocities in the independent test results, rather than measured with Doppler radar along the flight path. 55 gr FMJ boat-tail bullets typically measure about G1 0.24–0.26, so 0.271 may be slightly optimistic.

We plan to confirm it with further downrange velocity measurements (or a Doppler unit) and will update this page if the figure moves.

Reloading: always start from published load data for a 55 grain FMJ projectile and work up carefully. Never exceed the .223 Rem maximum pressure of 4300 bar (C.I.P.). Your velocities will vary with barrel length and load. Questions: info@leadandcopper.co.za