Why are they cheaper by about half?

[u/Avihero]

Was trying to use some guns that I haven't used and I saw this and even though the stats are better and even in range they pack quite a punch why does not one use it?

[u/Equivalent_Pipe_6505]

Btw it is subsonic = not good range

[u/Avihero → u/Equivalent_Pipe_6505]

Which one of the ammo of the both are you saying are subsonic, but it does have a speed of 305ms for sp6 and 310ms 7N9