The 5.45 doesn't mushroom like a soft point.
I've done some playing around with the 5.45X39.5 round. My AR-15 is chambered for it instead of 5.56 and the ammo I've been feeding it is the Bulgarian stuff that was used extensively against the Afghans. The Afghans also referred to it as the poison bullet (they actually accused them of using poisoned bullets) because the nasty wounds it created almost always got massively infected.
The bullets consist of a copper washed mild steel jacket with 5mm of air space at the tip, followed by a 2mm lead plug. then a steel core takes up the rest of the interior space to the base of the bullet. The void in the tip cavitates, causing the tip to bend over a bit when it strikes a "moist" target (water jugs, mud, flesh, ext.). This throws the bullet into a rapid spin. Generally about two complete revolutions in 8 or 9 inches.
I just bought another 1080 round can of Ukrainian 5.45 ammo. Can't wait to finish off the Bulgarian stuff so I try the new stuff out too.