Place player as NATO autorifleman.
place down blue basic ammo crate.
Pick up 30rd. 6.5mm tracers.
move to a thin sheet metal shed.
load the 30rd. tracers into MX SW.
Start firing at the shed, watch how the bullets curve and slow down.
Now load 100rd. 6.5mm tracers.
Repeat the test and watch how the bullets pass trough like butter.
Its the same bullet type, being fired out of the same gun, but the penetration is different.