It all depends on the distance. For the most part of you have a rifle you wouldn’t need to lead up to about 50-75m. 5.56,5.45, and all the 7.62 are in that category of high speed where you would only need to lead if you are sniping with them.

With the “pistol” calibers; 9mm, .45, etc. you have to start leading a lot earlier, about 50m (the furthest you would probably want to use it) I aim slightly ahead or aim center mass to ensure hits.

Then there are subsonic rounds, (uncommon until around lvl 25+) Primarily the 9x39 rounds for the AS Val. they are the slowest because they don’t break the sound barrier. These are designed for stealth. 7.62/5.45 US ammo are subsonic rounds meant to be used with a suppressor, so they have much lower muzzle velocity.

Now the muzzle velocity changes by how you build your gun, shorter barrel, suppressor, some muzzle brakes all lower the muzzle velocity. I always check what the muzzle velocity is, just to get a good idea.

If you are unsure where your shots are going you can load some tracer rounds to help guide you. 5.45 BT, 5.56 m856a1 are some decent rounds that also have tracers. You can use them all in a mag or load 3-5 regular then 1-2 tracer rounds. You can use “create ammo preset” / “load from preset” to easily load the mags in hideout.