[thegriz18]

I got to thinking tonight that we measure expanded bullets wrong. We measure what they look like when they are done fully expanding, and penetrating. I have a few PDX1 bullets that expanded, but not all of the petals folded down along side the bullet. Some are at almost a 90 degree angle, about 1/4 in from the center of the bullet. That got me thinking. At one point in the expansion of this bullet all the petals were at that point of their expansion and this bullet was over 1 inch in diameter or larger. Just thought I would throw that out there to see what everyone else thinks about that.

[freakshow10mm]

There is a right and wrong way to measure expansion.

This is the correct way:

http://www.m4carbine.net/showthread.php?t=26028

[thegriz18]

The HST and XPB have cutting petals as opposed to the GS and Ranger Bonded that don't. The cutting petals expanded to a larger diameter than the GS and Bonded bullets. Perhaps it is all a wash, but I don't think that there is much point in averaging out the smallest diameter and largest diameter. The HST and XPB are still bigger than the other two. The way he is doing it, all bullets are the same diameter. That maybe true in how they react in a target, but still the XPB and HST are bigger than the other two. Will that size increase performance? That's debatable.

[freakshow10mm]

Originally Posted by thegriz18

The way he is doing it, all bullets are the same diameter.

The method he illustrates is the industry method and the method of the IWBA as well as the FBI. A lot of manufacturers use the petals as the expansion measurement point but that's not the correct way to measure.

[N/Apower]

Handgun bullets fully expand within the first 2" if they are going to at all.

[vafish]

Originally Posted by freakshow10mm

The method he illustrates is the industry method and the method of the IWBA as well as the FBI. A lot of manufacturers use the petals as the expansion measurement point but that's not the correct way to measure.

I understand their thinking in averaging the measurements. They want to figure the volume of the permanent wound cavity which would be the diameter of the hole times the length of the hole.

But I look at it like a broad head arrow going through a deer, I think a bullet with larger petals sticking out will have a better chance of hitting more blood vessels and causing more bleeding.

[thegriz18]

Originally Posted by vafish

I understand their thinking in averaging the measurements. They want to figure the volume of the permanent wound cavity which would be the diameter of the hole times the length of the hole.

But I look at it like a broad head arrow going through a deer, I think a bullet with larger petals sticking out will have a better chance of hitting more blood vessels and causing more bleeding.

That is the same way I look at it.

[freakshow10mm]

The focus is on the permanent wound channel as that is the most consistent factor in effectiveness. Sure petals act like broadhead blades. I'm not sure why they wouldn't count the petals as the expansion and why they take the average really. Dr. Roberts over on M4C should be able to answer that.

[thegriz18]

Originally Posted by freakshow10mm

The focus is on the permanent wound channel as that is the most consistent factor in effectiveness. Sure petals act like broadhead blades. I'm not sure why they wouldn't count the petals as the expansion and why they take the average really. Dr. Roberts over on M4C should be able to answer that.

I always get the feeling that everything he does has a huge bias to the 45 ACP. Averaging expansion the way he does should favor 45 ACP over other rounds. I don't think there is much debate that he is for the most part, a heavy and slow guy.

[degoodman]

Originally Posted by thegriz18

I got to thinking tonight that we measure expanded bullets wrong. We measure what they look like when they are done fully expanding, and penetrating. I have a few PDX1 bullets that expanded, but not all of the petals folded down along side the bullet. Some are at almost a 90 degree angle, about 1/4 in from the center of the bullet. That got me thinking. At one point in the expansion of this bullet all the petals were at that point of their expansion and this bullet was over 1 inch in diameter or larger. Just thought I would throw that out there to see what everyone else thinks about that.

What you're describing is not likely. The petals don't open up like a flower. What typically happens is that the petals start to open from the front, and then they roll back along the bullet. The final expanded diameter is going to be pretty close to the maximum diameter at any point during the expansion process.

In your PDX1 rounds that have asymmetrical expansion, you're likely seeing a flaw in the jacket material that left one side thicker than the other, or more likely, the bullet upset during the terminal penetration and exposing the bullet to asymmetrical forces on the expanding HP.

And the reason for averaging the max and minimum expanded diameters is because the frontal area of the expanded bullet is what is delivering tissue crush. and tissue crush is what's doing most of the damage in the pernmenant would cavity. And those petals, despite what most people think, they're delivering "crush" damage as well, with maybe some extra tearing of the tissue, but not much else. anyone who thinks that they're cutting through tissue like a broadhead has probably never seen what a broadhead wound track looks like, nor compared that to what an expanding bullet does. Its not the same at all.

And on bullets with nasty looking talons, you may get a little extra cutting or tearing, but you're also losing alot of tissue crush to those gaps in the expanded bullet where there is no bullet to do damage.

Finally, the reason you measure the diameter at the front, and not down the petals, is because the frontal area is what's delivering crush. down the petal, you're displacing tissue by stretch without destroying it because of the angle of the petal. This is also the same reason that many FMJ's leave would tracks that are actually smaller that full bullet diameter.

[thegriz18]

Originally Posted by degoodman

What you're describing is not likely. The petals don't open up like a flower. What typically happens is that the petals start to open from the front, and then they roll back along the bullet. The final expanded diameter is going to be pretty close to the maximum diameter at any point during the expansion process.

In your PDX1 rounds that have asymmetrical expansion, you're likely seeing a flaw in the jacket material that left one side thicker than the other, or more likely, the bullet upset during the terminal penetration and exposing the bullet to asymmetrical forces on the expanding HP.

And the reason for averaging the max and minimum expanded diameters is because the frontal area of the expanded bullet is what is delivering tissue crush. and tissue crush is what's doing most of the damage in the pernmenant would cavity. And those petals, despite what most people think, they're delivering "crush" damage as well, with maybe some extra tearing of the tissue, but not much else. anyone who thinks that they're cutting through tissue like a broadhead has probably never seen what a broadhead wound track looks like, nor compared that to what an expanding bullet does. Its not the same at all.

And on bullets with nasty looking talons, you may get a little extra cutting or tearing, but you're also losing alot of tissue crush to those gaps in the expanded bullet where there is no bullet to do damage.

Finally, the reason you measure the diameter at the front, and not down the petals, is because the frontal area is what's delivering crush. down the petal, you're displacing tissue by stretch without destroying it because of the angle of the petal. This is also the same reason that many FMJ's leave would tracks that are actually smaller that full bullet diameter.

That actually makes a lot of sense. So I guess that I'm really getting the same thing with Ranger T or PDX1 bullets when it comes to crush. Makes me think I might just stick with bonded rounds. I have to ponder this some more. Both loads kicked butt in my informal testing.

[vafish]

Originally Posted by degoodman

anyone who thinks that they're cutting through tissue like a broadhead has probably never seen what a broadhead wound track looks like, nor compared that to what an expanding bullet does. Its not the same at all.

I've seen plenty of broad head wound tracks on deer. Last few years I have been shooting more with a crossbow then with a gun. I've never looked that closely at the wound tracks of deer I have shot with handguns.

But what you are saying is that the petals for the most part unless they have real sharp talons aren't cutting the flesh, like a broad head,they are just pushing it out of the way?

[degoodman]

Originally Posted by vafish

I've seen plenty of broad head wound tracks on deer. Last few years I have been shooting more with a crossbow then with a gun. I've never looked that closely at the wound tracks of deer I have shot with handguns.

But what you are saying is that the petals for the most part unless they have real sharp talons aren't cutting the flesh, like a broad head,they are just pushing it out of the way?

The petals that are facing forward are doing crush type damage even if the edges appear to be sharp. the parts that are folded back parallel to the direction the bullet is plowing through the tissue are just pushing tissue aside, like the bow of a boat parting the waters.

To illustrate the difference, go out and get yourself (not directed at you personally vafish) a nice Ribeye Steak and lay it on your counter. To simulate the broadhead wound, take your butcher knife, in an overhand stab, and plunge it inot the steak. Note the nice straight clean cut, that severs flesh in a nice clean line.

Next, take the same steak ob the other end, get a claw hammer and swing it full force at the steak. You now have a pretty good look at some crush damage. the stuff at the margin of the "wound" isn't cut, its mangled, torn, and well, crushed. that's what a bullet is doing.

For a "petal" simulation, hammer a dull twist drill bit through the steak. jacket material may have an edge, but it sure ain't sharp in a knife-like sense. Notice that most of the damage is still crush-like damage, maybe with a slight difference at the edges.

Now that you've done all those tests, take the claw hammer and hit yourself in the yam bag for ruining a good steak. You better grind that stuff up for the finest hamburger you've made in a while, or you can just turn in your man card at the nearest gay bar.

[fredj338]

What you're describing is not likely. The petals don't open up like a flower. What typically happens is that the petals start to open from the front, and then they roll back along the bullet. The final expanded diameter is going to be pretty close to the maximum diameter at any point during the expansion process.

Maybe, There really is no way to measure the petals at full expansion. before the fold. This lead bullet expands in petals & you can see how the expansion developes at certain vel levels. I haven't pushed them fast enough yet to get the petals to fold back.