.25 acp truncated bullet?

[Small_bore]

I've been told that in these smaller calibers the truncated type bullet is the most effective.
FMJ will penetrate, but might glance off bones and generally cause small wound channels. Also the idea of ball ammo simply "slipping through" one's body without doing much damage to anything other then what is exactly in front of it.
JHP might penetrate and give a large wound channel, but in calibers of .32 acp and below the penetration is really just not there.
A truncated bullet works like a FMJ, but instead of easily cutting a pathway through the flat tip seems to just bash it's way forward. Plus the sharp edges of the flat tip gives the bullet less of a chance to glance off bone.

Yes I know a gust of wind can stop a .25 acp (kidding ). Would a truncated bullet in .25 acp yield the best self-defense function then a FMJ or JHP?

[Archie]

The idea of carrying a .25 ACP pistol for self defense does not excite me, James Bond notwithstanding. However, if that's the only choice, one does one's best.

You are correct. An expanding .25 ACP bullet may expand, but at the cost of limited penetration. So the best choice - best being a relative term one understands - is a heavy FMJ round; 50 grains being the default weight.

You cite a truncated bullet. I presume you are suggesting a flat fronted bullet of conical shape forward of the bearing surface? I know of no such bullet currently made. (I did a short search, no such bullet for handgun use.)

Presuming one exists or could be made; due to limited effective range, the bad news is the person so armed is going to have to wait until the attack has his hands on one's throat and then deliver a contact wound, preferably to the center of the forehead. This is repeated until the attacker releases his hold.

If the attacker is armed with a knife, there are serious limitations to this plan of action.

I by no means recommend such a plan. I think a collapsing baton would be superior, barring physical handicap.

[Small_bore]

Truncated bullets are "flat-nosed" bullets.
The .40 S&W FMJ is a truncated bullet.
In talk I heard that truncated bullets are superior to plain round FMJ in terms of energy, being that "semi-wadcutter" appearance creating a more drastic hole.
As of now I carry a .25 until my .32 proves itself reliable after some TLC.

[Alpo]

Actually, that shape is termed "truncated cone", but as Archie said, there ain't no sucha critter for the 25 ACP. So, while the idea of using one isn't bad, without one to use, it's moot.