Hollow Points Filled with Powder Coat, What Happens?

[KVO]

Various experiments by others have addressed adding fillers such as silicone and wax to HP cavities to improve expansion with sometimes impressive results. Anyone that's PC cast HP invariably ends up with a few boolits having an excess of powder in the cavity. This begs the question of just what happens?

The following are all standard for caliber pistol velocity loads ranging from 900-1050fps cast from 20:1, fired into ballistics gel covered with x2 layers of a pink polo T-shirt. The pink fiber makes for nice contrast when assessing any plugging of the HP.

The boolit on the far left of each group intentionally had the HP cavity completely filled with PC powder before baking and looked like a flat nose boolit with a slight dimple after they cured. The other 4-5 projectiles to the right were coated and had excess powder tapped off as I would normally coat/load/shoot.

Here's what I found:

NOE 358-135 9mm (128gr):
223704
223705

Mihec 360-640 9mm (145gr):
223706
223707

NOE 403-200 WFN .40 S&W (180gr):
223708
223709

As can be seen, a varying degree PC plugging does occur and appears to have a more detrimental effect at lower velocities (heavier boolits), and larger cavities seem more susceptible to plugging than smaller ones. PC plugs in the nose do not behave like a ballistic tip or other expansion enhancer. My take away is that if there is a small amount of powder left in your HP cavities after coating, it's not enough to matter.

[Hickok]

Thanks for the great work and information!

[Wheelguns 1961]

Nice expansion!

[sureYnot]

Thanks for the great work and information!+1

Sent from my XT1710-02 using Tapatalk

[ThomR]

Those are pretty impressive results considering the HP cavities were filled with powder coat.

[KVO]

Bear in mind it's just the ONE boolit on the far left of each row that's PC filled, the others are a contol sample. Thanks for the positive feedback y'all!

[ThomR]

Bear in mind it's just the ONE boolit on the far left of each row that's PC filled, the others are a contol sample. Thanks for the positive feedback y'all!

I saw that in the first post. Powder coat inside the HP cavity was something I was wondering about since I'm planning on buying a HP mold from MP molds in a month or so.

[sutherpride59]

Very nice little write up!

[Landshark9025]

Was there any measurable difference in penetration?

[KVO]

Was there any measurable difference in penetration?

Yes.

NOE 135gr Plugged= 15.75" / Normal= 11-12.75"

MP 145gr Plugged= 15" / Normal= 11-11.75"

NOE 180gr Plugged= 16" / Normal= 10.5-11.75"

In experimenting with both impact velocity and cavity geometry (i.e. change of size or swaging different shapes into it) the trend I have seen is an increase in penetration on both ends of the spectrum. Less expansion= more penetration as expected. However, on the opposite end, once the expanded HP nose begins to "break over center" expansion starts to increase again. In other words when the expanded noses go from a somewhat flat face to a mushroomed profile that starts to peel back over the boolit/bullet shank the penetration goes back up because the frontal "crush" area is decreased (nod to all those big meplat fans). We end up with what is essentially a larger diameter blunt RN. This is all assuming of course that we have either at or very near 100% weight retention. Many of uber cool looking jacketed bullets I have tested have that characteristic peeled banana look will penetrate substantially deeper in the same test medium. We are either transferring energy and thereby crushing tissue, or wedging some of it out of the way. There is also the "when" of expansion, are we gradually opening and thereby able to push deeper, or expend most of the kinetic energy and thus penetrative ability of the projectile within the first few inches? There is no free lunch in terminal ballistics.

One thing that is not translated is seeing how the blocks react in real time. The typical service pistol rounds make the blocks quiver a tiny bit on impact. A magnum level load even from a snubby makes the blocks jump. Shooting a 2" model 19 with a stiff load of 2400 and a hollow pointed 358156 cracked the test table underneath my blocks just from the energy transfer, no direct projectile impact. Step up to a 6" .44 with magnum loads and an aggressively expanding boolit will flip the blocks over. Before I'm accused of being brainwashed by gelatin, I will be the first to say there is more to killing power than just kinetic energy transfer; real game animals or otherwise do not do Die Hard back flips when shot.

[Landshark9025]

Yes.

NOE 135gr Plugged= 15.75" / Normal= 11-12.75"

MP 145gr Plugged= 15" / Normal= 11-11.75"

NOE 180gr Plugged= 16" / Normal= 10.5-11.75"

snip

Before I'm accused of being brainwashed by gelatin, I will be the first to say there is more to killing power than just kinetic energy transfer; real game animals or otherwise do not do Die Hard back flips when shot.

Thanks. I assumed as much, but wanted to be sure.

And yeah, there's a ton of variables in the real world. Some animals are just less willing to lay down than others. But it's SUPER valuable to know that a hollow points filled with powder coat does not act like a ballistic tip. It makes sense when you think of it. Most ballistic tips are shaped a certain way, have an air gap underneath them, etc.

Good to see some tests to back up the theory, though.

[Forrest r]

To me it looks like they expanded less and have more pink cloth stuck to them. All bullets (far left).

[WheelgunConvert]

Almost like the PC was a binder that restricted the expansion.

Interesting project. Thank You for sharing the results

[Forrest r]

Almost like the PC was a binder that restricted the expansion.

Interesting project. Thank You for sharing the results

+1^^^^^

It's almost like the shirt was some sort of polyester. Heat/friction of plastic on plastic bonded the shirt to the bullets with the polyester filled hp's.

[KVO]

The shirt used on these was definitely a synthetic rayon/polyester blend. The fibers are "pluckable" off the nose of the boolits. Difficult to see in the pix but if you look at the NOE 135gr in the first pic thy there are hard chunks of PC in the center of the cavity that did not spread out.

[KVO]

I'll take pretty much any of them, plugged or not, over XTPs. 45acp, Mihec 200gr with a modified cavity vs 185gr XTPs.

224016
224017

[ThomR]

I'll take pretty much any of them, plugged or not, over XTPs. 45acp, Mihec 200gr with a modified cavity vs 185gr XTPs.

224016
224017

Those are pretty impressive results!

[galaxy]

Fantastic write-up!

[WheelgunConvert]

Was it a penta pin that you used to cast the HP?

[KVO]

Penta pin plus 5 lobe torx safety bit used to skive the cavity. Short version is that boolit needs some help expanding at lower velocities but does marvelous at mid range and up for 45acp loads in a 5" barrel. Away from home for the week, so I don't have pictures available but can upload some in the near future. I tried a progressive series of smaller to larger torx bits to evaluate the effect of each step up in size. I can post some of that test if it is of interest, not sure if that info would be better off in a new thread.