9, 40, 45 vs pickup truck bed

[rglong81]

There's an old pickup bed I was taking shots at one day. Hollowpoints and FMJ in 9mm and 40 S&W would penetrate the side (two layers of metal) but 45 acp just made big dents in the first layer. So I purchased some FMJ Semi-wadcutters and they made it through both layers just fine. 230 grain for all three types of 45 acp. Anyone care to speculate why the the hollowpoint and round nose bullets didn't penetrate but the semi-wadcutters did?

My best guess is that the bigger diameter bullet spends more of it's energy on impact than the smaller rounds. And the smaller rounds having a more narrow diameter focus that energy in a more centralized spot rather than spreading it out. The more conical shape of the 40 S&W FMJ and 45 FMJ-SW being tapered may be why they penetrate just as well. But it doesn't explain why the 45 round nose didn't penetrate or why the HP 40 S&W did.

 

[dogtown tom]

rglong81 .... Anyone care to speculate why the the hollowpoint and round nose bullets didn't penetrate but the semi-wadcutters did?

Penetration isn't only about the bullet profile.
Bullet weight, shape, composition, velocity........all impact how far a particular load will penetrate. Using a low velocity Winchester White Box 230gr FMJ doesn't give the same results as high velocity 230gr FMJ.

My best guess is that the bigger diameter bullet spends more of it's energy on impact than the smaller rounds.

Don't fall for the fallacy of energy dump.

And the smaller rounds having a more narrow diameter focus that energy in a more centralized spot rather than spreading it out. The more conical shape of the 40 S&W FMJ and 45 FMJ-SW being tapered may be why they penetrate just as well.

Ice picks penetrate further than baseballs.

But it doesn't explain why the 45 round nose didn't penetrate or why the HP 40 S&W did.

It ain't the bullet shape.

 

[ku4hx]

This reminds me of an old 1960ish TV ad for pad locks. A certain make of padlock was shot with a .44 Magnum and it did essentially no damage to the lock. The impression was the lock was ultra tough to stand up to the mighty .44 Magnum.

What wasn't spoken to was the .44 Magnum cartridge shown as it was being loaded into the cylinder was clearly a factory round with the soft lead bullet common to the time. Couple that with the fact the lock was suspended by a chain or piece of cable and free to swing and you had a pretty good typical misleading commercial setup.

The ad eventually disappeared and maybe for good reason. The moral of the story is there is more than one way to skin a cat and penetration is generally a quite illusive target.

 

[Arkansas Paul]

What range are we talking about?
Just curious as to whether the MV had dropped off a significant amount.

 

[jmr40]

45 ACP has always been a poor choice at barrier penetration. I discovered that 1st hand years ago shooting at targets of opportunity at an old dump. Back when such things were legal and common. I was using some old metal 1 gal paint cans for targets. Everything but 45 ACP completely penetrated. 45's would usually penetrate one side, but hit the curved back side and just spin around leaving the bullets inside the can.

The military concluded that 9mm was a better combat round during WW-2 for the same reasons. The 45's were not getting through barriers that the German 9mm were. After the war a series of tests were conducted and the Army wanted to adopt 9mm in 1946. One of the tests involved penetrating a steel helmet. The 9mm loads still penetrated out past 100 yards while 45's just bounced off at ranges greater than 10 yards.

Bullet speed and concentrating the energy into a smaller area give penetration. Tank rounds designed to take out other tanks shoot a very small diameter sabot round at very high speed. When it hits all the energy is concentrated in a small area and makes a very small entrance hole through several inches of steel.

The semi-wad cutters did a better job of concentrating the energy into a smaller area and allowed it to punch through.

 

[dvnv]

Velocity is an important factor when trying to penetrate metal, not so much in flesh.

 

[rglong81]

I'd say about 35' to 40' at a 45° downward angle as the box was on the ground.

I know old law enforcement "armor peircing" ammo had a pointy red tip. Icepicks vs baseballs makes it sound like shape has a lot to do with it. I can't speak to it personally but things I have read and seen pictures of on autoglass show 45s nearly disintegrating while 9s can retain most if not some of their mass after passing through glass. That larger surface does appear to distribute the energy more on impact than smaller and pointer objects. Like a bed of nails can distribute weight but just a few nails would ruin your day. I'd genuinely like to understand.

As far as the padlock story goes, interesting, but I'm not talking about soft lead bullets. All were jacketed hollowpoint, jacketed round nose, or jacketed and tapered flat tips in the case of the 40 S&W and 45 SW. Believe it or not I am not trying to sell you a truck bed full of bullet holes. :-D

Edit: Thank you jmr40. Makes perfect sense to me.

 

[bfalcon00]

Did you happen to chrono the factory ammo to see if the velocity was about the same?

 

[dogtown tom]

ku4hx This reminds me of an old 1960ish TV ad for pad locks. A certain make of padlock was shot with a .44 Magnum and it did essentially no damage to the lock. The impression was the lock was ultra tough to stand up to the mighty .44 Magnum.

What wasn't spoken to was the .44 Magnum cartridge shown as it was being loaded into the cylinder was clearly a factory round with the soft lead bullet common to the time. Couple that with the fact the lock was suspended by a chain or piece of cable and free to swing and you had a pretty good typical misleading commercial setup.

The ad eventually disappeared and maybe for good reason. The moral of the story is there is more than one way to skin a cat and penetration is generally a quite illusive target.

I remember those ads, they ran for decades.
Here's one that ran during the Super Bowl:https://www.youtube.com/watch?v=-HvOhO8f0wc
Whether shot with a .44mag or .30-06............aiming as they do in the video is very misleading. A padlock isn't defeated by shooting a hole through the body, but by downward force to separate the shackle from the lock body.

 

[BobWright]

Penetration is a function of sectional density.

That is, the weight compared to the cross section, generally a function of length, all other things being equal. That is what gives those armour piercing darts such penetrating power. Velocity helps, too.

With a bullet having a gilding metal jacket and lead core, a 180 gr. 9mm will penetrate deeper/better than a 180 gr. .40 caliber bullet, and that better than a 180 gr. .45 caliber bullet, velocities being the same.

Bob Wright

 

[Steve C]

The FMJ semi wadcutters where likely lighter in weight than 230 and ran at a higher velocity so they penetrated better than the 230gr FMJ. A flat nose bullet has a bit less deflection than a RN bullet on any flat object not hit perfectly perpendicular.

 

[351 WINCHESTER]

I shot my brother in laws 65 Chevy p/u bed with a fmj .45. It penetrated the drivers side and was stopped cold by the other. It would probably be a thru and thru shot on todays truck beds.

 

[Baron_Null]

The FMJ semi wadcutters where likely lighter in weight than 230 and ran at a higher velocity so they penetrated better than the 230gr FMJ. A flat nose bullet has a bit less deflection than a RN bullet on any flat object not hit perfectly perpendicular.

In the OP it was stated that all 3 different types of .45 were 230 grain, so differences in bullet weight as a factor looks like it's out.

Deflection seems like it would be a possible answer, but I'm so uneducated on the topic that speculation on my part with regards to possible causes would just add to misinformation, which I definitely do not want to do.

One thing I do have to ask, though, was the construction of the bed similar at every point you tested on? While I'm not going to suggest that it's the reason that the .45 failed to penetrate, it is possible that difference in geometry skewed results.

 

[CDW4ME]

357 Sig would likely fare well in that test.

 

[wow6599]

357 Sig would likely fare well in that test.

Same as a +p 9mm I suppose.......