JSP for short,
jacketed soft point bullets feature a
copper jacket and an exposed
lead tip.
Softpoints are a
specialized form of
bullet that is used when a
compromise between the
penetration of an
FMJ round and the
expansion of a
JHP round is needed.
It is a jacketed round but has the tip or ogive unjacketed to expose the soft lead core which will then deform and expand upon impact.
Since it does not use a hollowpoint to induce expansion, it will consistently expand upon hitting soft tissue or even a hard surface. JHPs can get plugged up by clothing material or glass if you have to shoot at someone through a barrier.
Unless that someone was also shooting at you, you will have a very hard time explaining to a judge or jury why the hell you were doing that. Be advised.
For unarmored targets, JHPs will still be far more devastating than softpoints but as long as you do your part, softpoints are not a bad choice for a self defense round.
Lead is relatively soft and will deform and flatten upon impact but will not "mushroom" like a JHP. This gives a good compromise between penetration and expansion. It sits between FMJ and JHP rounds in terms of penetration and expansion.
A good thing with JSP ammo is that it retains the "ball" profile and will have less feeding issues than regular JHP rounds. Most preferably used in low velocity cartridges such as the .45 ACP and 380 ACP as higher velocity rounds like 9mmx19 and .357 Magnum might still over penetrate. Take note that JSP rounds have very low armor piercing capabilities and are only used to shoot at unarmored targets.