How Reliably do Modern JHP's Expand?

[SwampDweller]

Occasionally I re-read the old FBI Handgun Wounding Factors and Effectiveness paper from the late '80s. There was one line in particular that said that hollow point bullets only expand 60-70% of the time at best.

The paper says this:

"Damage to the hollow point by hitting bone, glass, or other intervening
obstacles can prevent expansion. Clothing fibers can wrap the nose of the bullet in a cocoon like manner
and prevent expansion. Insufficient impact velocity caused by short barrels and/or longer range will
prevent expansion, as will simple manufacturing variations. Expansion must never be the basis for bullet
selection, but considered a bonus when, and if, it occurs. Bullet selection should be determined based
on penetration first, and the unexpanded diameter of the bullet second, as that is all the shooter can
reliably expect. "

It made me think, how reliable are hollow points in expansion today? Is there a percentage number that can be ascribed? Considering that the switch back to 9mm was facilitated by the advent of well-designed expanding loads, there must have been a huge increase in the reliability of expansion. Still, everything can fail.

[BehindBlueI's]

Blanket statements are hard, as there is still a lot of variation in brand, cartridge, and sometimes barrel length. The 'top shelf' modern offerings expand pretty reliably in common duty calibers from common barrel lengths. Old school/second tier offerings less so, especially at lower velocities from shorter barrels or marginal cartridges. HSTs, Gold Dots, Critical Defense, etc. seem to expand at least partially even with bone strikes and intermediate barriers.

[SJC3081]

Does it really matter. Use a load with a good history of reliability and performance. Make good hits first and expansion is icing on the cake.

[DocGKR]

Modern JHP ammo that meets FBI/IWBA style barrier blind, robust expansion protocols tends to work well.

[DDTSGM]

Does it really matter. Use a load with a good history of reliability and performance. Make good hits first and expansion is icing on the cake.

Agree in substance.

I think many folks are concerned with a non-expanding hollow point acting like a FMJ and over-penetrating. In most cases that doesn't matter, until it does. \/^O\/

[HCM]

Agree in substance.

I think many folks are concerned with a non-expanding hollow point acting like a FMJ and over-penetrating. In most cases that doesn't matter, until it does. \/^O\/

Agree that in regard to terminal effects, expansion is a very, very, distant second to shot placement.,

Bullets do funny things in real life. If you are using ammo that meets the FBI specs and you hit your assailant/ suspect you’ve done your due diligence. Beyond that …

[LockedBreech]

I’m sure modern ones are better than 60-70% but I think it’s good practice to pick a load from Doc’s list and then train as though you’re shouting FMJs. If you plan for the worst you can only be pleasantly surprised.

[Shotgun]

Modern JHP ammo that meets FBI/IWBA style barrier blind, robust expansion protocols tends to work well.

We are way past the late 80s. Heck, we went through the .40 craze since then and now back to 9mm for most. Doc has a sticky, https://pistol-forum.com/showthread....f-Defense-Ammo , of acceptable ammo.

[SwampDweller]

I feel like this marks a stark contrast with the FBI's mindset during the late 80s/early 90s, whereas in the FBI paper in the 80s, they said expansion shouldn't be counted on and factor into the decision for ammunition ("Bullet selection should be determined based on penetration first, and the unexpanded diameter of the bullet second") but now the extremely improved 9mm loadings seem to have changed that view.

[the Schwartz]

I feel like this marks a stark contrast with the FBI's mindset during the late 80s/early 90s, whereas in the FBI paper in the 80s, they said expansion shouldn't be counted on and factor into the decision for ammunition ("Bullet selection should be determined based on penetration first, and the unexpanded diameter of the bullet second") but now the extremely improved 9mm loadings seem to have changed that view.

Absolutely not.

Both penetration and expansion are required in order for duty/issued ammunition to pass the F.B.I. test protocols.