Does a bigger caliber hollowpoint expand (better) at a slower speed?

They don't have to. They're already there.

Modern JHP's are designed to reliably expand in a certain "window" of velocities specific to that bullet/caliber.

So, in this case, yes--THAT bullet will get robust expansion at that velocity; a 115gr 9mm Gold Dot might not.

Does a bigger caliber hollowpoint expand (better) at a slower speed?

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Well, that's the ballistics physics of bullet/cartridge design.

Can't say as I've seen solid independent test results of such "windows" of performance clearly showing (all other things being equal) that a given caliber/speed combination reliably expands better than another. It would be interesting to do a significant, large test of each and every available handgun cartridge in all caliber/weight/speed combinations in calibrated ballistic gel, to allow some good stats to be evaluated. Then we might see some strong correlations, perhaps even sufficient to identify key causal factors ... in the bullet's shape, density/shape/matl, design aspects, weight, speed, barrel characteristics, environmental characteristics, etc.

Thanks for the link! I know the good parson and he's a guy who'd do to ride the river with. No flies at all on his .45 Colt revolvers and that load.

The size of the hollow point certainly isn't all there is to the expansion equation. Bullet material plays its part and can negate the benefit of the largest hollow point.

A specific JHP bullet driven to a higher speed than another will have larger expansion, and will usually have lesser penetration.

Here's an example from Andreleger2001's channel. In this video, the added velocity of the +P+ loading caused expansion that is obviously much larger than a standard 115gr Gold dot at standard velocities would have.

9mm Luger - Speer 115 Gr. +P+ Gold Dot - Ammo Test - YouTube


When any JHP bullet is fired at speeds below the velocities it is designed to expand at, there will be minimal to no expansion.

It's difficult, if not impossible , to predict what any JHP will do unless you know exactly what will happen to it after it leaves the barrel. If you don't get the result you want with the first one, let fly with number two, three, four etc.

A specific JHP bullet driven to a higher speed than another will have larger expansion, and will usually have lesser penetration.

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Unless you give it enough velocity to penetrate to the depth you desire.

It also depends on the type, consitency and density ofthe tissu it passes through.

40Bob said:

Unless you give it enough velocity to penetrate to the depth you desire.

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For expanding rounds, bullet design has greater influence in penetration than velocity has.

When traveling through flesh, more velocity =/= more penetration unless you're using a bullet designed to be armor penetrating, non-expanding or has "controlled" (limited) expansion like a Hornady XTP. XTPs won't expand much more than 1.5x their diameter regardless of their velocities.

If you shoot a bullet into something like wood that would not allow JHP expansion, your statement is true.

Fisher, my point is I can take a 44 magnum bullet @ 1250 fps that mushrooms out to the same diameter that a 45 ACP bullet does @ 850 FPS and penetrate deeper. So, yes more velocity (energy) can overcome the resistance of the media the bullet is passing through and penetrate deeper.

You are correct in that, bullets at the same velocity, the smaller diameter will penetrate deeper.

Read the other day that soft lead bullets pushed @ subsonic speeds can cause more tissue damage than expanding bullets. While deformation can be fine tuned with velocity & bnh the biggest factor is the fragmentation of hollow points & the energy necessary for full expansion of expanding bullets. There seems to be a high failure rate of full expansion due to clothing, bone & cartilage the bullet might pass through.
After reading the article I has to agree to some extent with the author's opinion. It was somewhat biased in favor of the lead bullet but still had valid points.

It is all a Crap Shoot with various Pistol bullets and velocities. The first rule is shoot till the BG stops doing what he is doing. Until then you can believe that the fight is not over. Shot placement is first and the damage it does, then how much it expanded. Damage done on the way into is what counts.

Regardless of terminal ballistic performance and other technical scientific data, if I'm in a life or death situation I'm pulling the heck out of the trigger until the threat stops. 19+1 is a beautiful thing.

A 9mm may expand but a .45acp will never shrink....

^^+1

great replies here thanks!... I keep hearing to just use wadcutters for my colt 45 for home defense round since most hollowpoints wont expand under 1000fps. Well obviously its not the case here. These Gold Dots do look like an excellent round for the colt 45 according to the article.

Blaze 57 said:

great replies here thanks!... I keep hearing to just use wadcutters for my colt 45 for home defense round since most hollowpoints wont expand under 1000fps. Well obviously its not the case here. These Gold Dots do look like an excellent round for the colt 45 according to the article.

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Once upon a time, that was pretty much true; and with older design hollow points, it is often still true.

However, the newer designs--that Gold Dot being one of them--will open reliably at slower speeds.