Question 1

What FPS is 1 joule on a 0.40g BB?

Accepted Answer

232 FPS. The formula: v = √(2E/m), converted to feet per second. On 0.40g (0.00040 kg), 1.0 J of energy equals 232 FPS.

Question 2

What's the max FPS for CQB with 0.40g BBs?

Accepted Answer

Most indoor CQB fields cap energy at 1.14 J, which is 248 FPS on a 0.40g BB. Always confirm with your field — some chrono everyone on 0.20g regardless of what you play with.

Question 3

Is 0.40g a good BB weight?

Accepted Answer

0.40g is a heavy BB suited to high-energy DMR and sniper setups. It holds trajectory in wind much better and is less deflected by leaves and brush, at the cost of lower velocity.

Limit	Joules	Max FPS on 0.40g
Indoor CQB	1.14 J	248 FPS
Outdoor AEG	1.49 J	283 FPS
UK legal max (VCR Act)	1.32 J	267 FPS
Outdoor DMR	1.88 J	318 FPS
Bolt-action sniper	2.32 J	353 FPS

Velocity	Energy	Metric
100 FPS	0.19 J	30 m/s
120 FPS	0.27 J	37 m/s
140 FPS	0.36 J	43 m/s
160 FPS	0.48 J	49 m/s
180 FPS	0.60 J	55 m/s
200 FPS	0.74 J	61 m/s
220 FPS	0.90 J	67 m/s
240 FPS	1.07 J	73 m/s
260 FPS	1.26 J	79 m/s
280 FPS	1.46 J	85 m/s
300 FPS	1.67 J	91 m/s
320 FPS	1.90 J	98 m/s
340 FPS	2.15 J	104 m/s
360 FPS	2.41 J	110 m/s
380 FPS	2.68 J	116 m/s
400 FPS	2.97 J	122 m/s
420 FPS	3.28 J	128 m/s
440 FPS	3.60 J	134 m/s
460 FPS	3.93 J	140 m/s
480 FPS	4.28 J	146 m/s
500 FPS	4.65 J	152 m/s
520 FPS	5.02 J	158 m/s
540 FPS	5.42 J	165 m/s
560 FPS	5.83 J	171 m/s
580 FPS	6.25 J	177 m/s
600 FPS	6.69 J	183 m/s

FPS to Joules — 0.40g BB Chart

Field limits on 0.40g

Full conversion chart

FAQ

Other BB weights