.45 FMJ penetration differences

[cdoc42]

This is a spin-off of the thread about gas checks because it queries a different situation.

In that prior thread, I questioned whether or not there would be a difference in the momentum or penetration when comparing a bullet with a complete closure of the bullet base with copper vs one with an exposed lead base which was really the basis for a question regarding the need for a gas check.

The difference is this:

I went to range today with .45 APC's loaded with 4.0gr of Clays, a large pistol primer, a COL of 1.600".

The only difference was the use of a Rainier 230gr FMJ ( completely enclosed base) and a Precision Delta 230gr bullet that has an exposed lead base, surrounded at the extremity of the base with the extension of the copper jacket.

I did not have the opportunity to chronograph the speeds.

I fired at a Cuninsart Non-Stick Frying pan at 15 yards. The Rainier rounds made an entrance and exit hole size comparable to the .45 APC diameter expectation. The Precision Delta rounds, in two instances, opened a hole but left a hanging portion of metal that looked like a door was partially opened.
A third shot found the bullet stuck on the hole, with the exit partially opened.

We discussed if there might be a difference in penetration and/or momentum based on the relative difference between the copper and lead weight of these bullet types. The opinion offered was there is no significant effect.

What might explain what I experienced today?

[Marco Califo]

Frying pans make expensive targets. Once struck, the resistance will be compromised and unreliable for consistent efects of follow-up shots. The exposed lead has zero effect on terminal ballistics.
I have done a better test, with a iron bath tub abandonded at an old mine site. It was 9mm fmj and they all penetrated cleanly. That is the sum of what could be infererred. I dont think my range allows frying pans or bathtubs to be placed as targets.

[Aguila Blanca]

Originally Posted by cdoc42

The only difference was the use of a Rainier 230gr FMJ ( completely enclosed base) and a Precision Delta 230gr bullet that has an exposed lead base, surrounded at the extremity of the base with the extension of the copper jacket.

I did not have the opportunity to chronograph the speeds.

I fired at a Cuninsart Non-Stick Frying pan at 15 yards. The Rainier rounds made an entrance and exit hole size comparable to the .45 APC diameter expectation. The Precision Delta rounds, in two instances, opened a hole but left a hanging portion of metal that looked like a door was partially opened.
A third shot found the bullet stuck on the hole, with the exit partially opened.

Point 1: Energy, or momentum, is basically a function of mass times velocity squared. 230 grains is 230 grains. IF the two different bullets are launched at the same velocity, they will have the same energy/momentum. However, you don't know if they launched at the same velocity, so there's problem number one.

Point 2: Your target wasn't ballistic gel (or the Clear Ballistics substitute). You were shooting a chunk of cast iron (?? What was the frying pan made of?). The hardness of the bullet would, I think, have a significant effect in that situation. First, the lead cores of the two bullet types may have a different hardness. Second, the Rainier copper plating may (probably does) have a different hardness than the copper or brass alloy used in the Precision Delta jacket. Third, as we covered in your other thread, the jacket of the Precision Delta bullets is significantly thicker than the plating on the Rainier bullets.

In short, your experiment doesn't appear to have been set up very well to get an "apples to apples" comparison. There are just too many variables to draw any conclusions from your results.

[44 AMP]

Point #3
(combining #1 & #2)

you're shooting two different loads without knowing all the ways of HOW they are different, and seeing two different results, and assuming the reason is one has the bullet base covered with copper and the other does not.

This is the fact of the way they are made but it is not a valid assumption that difference in performance shooting a frying pan is only the result of exposed lead at the bullet base.

There are a lot of factors involved that you are not mentioning, perhaps not aware of, but that can be significant, just as there are other factors that are insignificant.

My experience is that if bullet A punches a clean hole through something and bullet B does not, differences in the base of the bullet are way down the list of possible reasons.

[Aguila Blanca]

Originally Posted by 44 AMP

My experience is that if bullet A punches a clean hole through something and bullet B does not, differences in the base of the bullet are way down the list of possible reasons.

An example of this might be U.S. military ammo for the M16.

The stuff we had when I was in Vietnam was the 55-grain M193 cartridge. Along about 1980 (or so), the U.S. and NATO settled on the slightly heavier (and longer -- the extra weight had to go somewhere) 62-grain M855 cartridge. Both are what I regard as spire point bullets, with a sort of rounded "semi-boattail" base.


M193 on left, M855 second to left

The trajectories of the two are VERY close out to about 200 meters -- close enough that a rifle zeroed for one can be used with the other without resetting the zero. The big difference between them is in penetration. The M855 has a steel penetrator tip that allows it to penetrate the old steel pot helmet (such as I wore in Vietnam) out to 600 meters. The M193 can't do that. So what makes the difference in penetration between those two rounds is primarily the bullet construction. The M855 is hard enough to punch through the steel helmet -- the M193 isn't.

[reddog81]

Where you hit the frying pan probably had a bigger effect than anything else. Hardness or composition of the copper jacket could make a difference. Hardness of the lead inside the bullet could make a difference. Slight variations of the bullet nose profile could make a difference. Random variations in velocity would make a difference.

[44 AMP]

The M855 is hard enough to punch through the steel helmet -- the M193 isn't.

Not quite accurate. The M193 bullet is plenty "hard enough" and will punch through the old GI steel pot easily, IF it is moving fast enough. (and of course assuming a square hit so the bullet is not deflected off the curved surface).

At 600 meters its not moving fast enough, anymore. At 500m and under it is.

Its a combination of speed AND bullet construction TOGETHER.

The M855's steel penetrator didn't come about to shoot GI helmets, (or fryingpans ) it was developed due to the concern that our most likely enemy at the time, Warsaw Pact Forces, were equipping their troops with body armor and our standard M193 round might not be enough to defeat that, at range.

It is somewhat ironic, we never wound up fighting the Warsaw Pact. Also the punch through the GI helmet thing was an Army requirement originally created to disqualify the AR-15 being considered for adoption. Or so the story goes. The original AR-15s were .222 Rem, and some people in the Army, not wanting the small bore round, or its rifle, created the requirement deliberately as something the .222 could not do. IIRC it was punch through a GI steel pot at 500m.

The .222 couldn't, the .222 Rem Mag could, but was just too long to work in the AR action. Those folks hoped that would kill the whole idea. It didn't, it led to the creation of the .223 Rem (5.56mm) round that could meet the requirement and fit in the AR, and the rest is history.

I do find it amusing that now the requirement being talked about is up from 500 to 600 meters.....I wonder where that will finally end up...

Back to the .45....45acp rounds are poor choices for penetrating hard targets, the relative low speed and stubby bullet shape works against that. And while something of concern for military and police, I think it is, and should be less of a concern for civilian self defense use.

Unless, of course, you've got to shoot the guy wearing a stove door under his serape' and you know he is wearing it...

[Aguila Blanca]

Originally Posted by 44 AMP

Not quite accurate. The M193 bullet is plenty "hard enough" and will punch through the old GI steel pot easily, IF it is moving fast enough. (and of course assuming a square hit so the bullet is not deflected off the curved surface).

At 600 meters its not moving fast enough, anymore. At 500m and under it is.

That's why I specifically mentioned 600 meters.

[cdoc42]

"Where you hit the frying pan probably had a bigger effect than anything else. Hardness or composition of the copper jacket could make a difference. Hardness of the lead inside the bullet could make a difference. Slight variations of the bullet nose profile could make a difference. Random variations in velocity would make a difference."

I can understand the existence of the subtle differences offered, but I'm having trouble comprehending how they apply to the circumstance I described.

Why would where the pan was hit make a difference? This was, as stated, a "non-stick" fry pan; it was not cast iron. The hits described were all in the central area; none in the upsloping sides. I was only 15 yards away. If the Rainier bullet was going 800 fps, how much slower would another bullet of the same weight and similar shape, given the same powder charge, have to be going to fail to completely penetrate the pan?

I suppose it would make sense to chronograph these cartridges to settle that question.

But doesn't this at least raise a question about how one should choose a replacement bullet given shortages, etc., see these days? Both bullets blasted water bottles apart and made holes in paper. But had I not shot both at the fry pan, I would not have known the P.D. bullet is not likely to be defensibly reliable, compared to the now extinct Rainier.

Edit: I was in the midst of preparing this and I posted it without seeing 44amp's explanation above. Thanks for that. And the little smiley face emoji, that was a perfect inclusion. It's fun having fun while being educated.

[ballardw]

Originally Posted by cdoc42

Why would where the pan was hit make a difference? This was, as stated, a "non-stick" fry pan; it was not cast iron. The hits described were all in the central area; none in the upsloping sides. I was only 15 yards away. If the Rainier bullet was going 800 fps, how much slower would another bullet of the same weight and similar shape, given the same powder charge, have to be going to fail to completely penetrate the pan?

Most of these non-stick, and other fry pans, start out as a large disk of metal. Then they are die struck to make the pan shape. Where the "flat" meets the curve a certain amount of metal stretching is going resulting in thinner metal. But that area is also "work hardened" a bit more than the center of the bottom.

The episode of "How Its Made" I saw did not show any specific annealing step or other treatment intended to change the overall hardness of the metal moved around so whether the bottom center is tougher than the sections near the edge would be a question. With a used pan then history of use/abuse/overheating may change the hardness differently by area depending on exact use and specific alloy involved.

[higgite]

Was the pan equally braced/supported for all shots or did shots early in the string deteriorate support for shots later in the string?

If nothing else, you've convinced me not to make or buy body armor that incorporates Cuisinart frying pans.

[Aguila Blanca]

Originally Posted by cdoc42

This was, as stated, a "non-stick" fry pan; it was not cast iron.

"Non stick" describes a coating -- typically Teflon, but I don't play with Cuisenart cookware so I don't know what they use -- not the material of the pan to which the coating is applied. If it's not cast iron, it could be aluminum (either cast, spun, or stamped), or steel.

All of which is immaterial. Whether or not the base of the bullet is plated has virtually nothing to do with the bullet's ability to penetrate the pan. There are a great many variables at play here, most of which have been mentioned in previous posts.

BTW: I see you still refer to the Rainier bullets as FMJ.

The only difference was the use of a Rainier 230gr FMJ ( completely enclosed base) and a Precision Delta 230gr bullet that has an exposed lead base, surrounded at the extremity of the base with the extension of the copper jacket.

I thought we had settled that in your other thread. They are not FMJ, they are plated. The 'J' in "FMJ" stands for "jacket," which is not the same as plating.

[reddog81]

Originally Posted by cdoc42

I can understand the existence of the subtle differences offered, but I'm having trouble comprehending how they apply to the circumstance I described.

Round to round variation in velocity could be enough to explain the differences you are seeing.

If you look at ballistics gel testing using the same lot of ammo you will have quite the variation in penetration and expansion. Ballistics gel is used because it is supposed to be relatively uniform from shot to shot. To assume you'd see the exact same result with each shot on a steel pan is not reasonable. Look at the bottom of the pan, is it uniform thickness in all areas? Once the pan is shot a couple of times the surface is going to be stretched and warped. Was every shot at the exact same angle?

[Unclenick]

Cdoc42,

I think the answer to your question is squirting.

First, your terminology may confuse others. The Raniers are not FMJ. They have a relatively thin and soft electroplated copper layer applied to the outside. An FMJ is a cup-and-core bullet, whose jacket is formed by stamping a gilding metal from sheet stock, then using dies to form the bottom of the cup into the bullet nose shape, then using a press to swage a precisely sheard (for consistent weight) slug of lead wire into it with enough pressure to make it take the shape of the inside of the jacket (which is still supported by a die), and folding the back edges of the jacket cup over the base as far as they will go. This makes a thicker and harder outside surface than the plating does. You can test this for yourself by placing one of each bullet type on an anvil and smacking them with a hammer to observe what happens and how well they resist the hammer blow.

The importance of covering exposed lead bullet metal is the result of EPA indoor range air quality regulations. They hjave caused indoor range owners to forbid exposed lead for fear of their lead levels testing too high and them recieving a fine. A good argument can be made that it is only the outside corners of the bullet base that really have to be covered to prevent gas cutting, but rules and regulations often are unencumbered by clear thinking.

About forty years ago I knew a fellow who experimented with armor-piercing bullet design. If you have a soft enough bullet and it starts a hole in something, it turns out the main mass of lead will funnel through the hole, squirting out the other side, having bee been effectively fluidized by the event. The thicker, harder, solid nose of the FMJ may well prevent that from occurring. On steel, FMJ's tend to flatten and tear open and the lead then spreads out and flies away from the POI radially.

The other factor is the different bullet hardnesses can produce velocity differences that are sometimes enough to alter terminal performance.

[cdoc42]

Unclenick, as usual, you are correct. My age notwithstanding, I still viewed"FMJ" as just that - a bullet completely covered from "tip" (head) to "toe" (base) with copper. That is virtually what I see with every rifle and handgun caliber I've reloaded for 44 years, with the exception of .223 after I got into AR-15's. The only differentiation between FMJ or not in rifle is the absence of a rapidly expanding tip (i.e, soft point, ballistic tip, etc.)

Only in .223, and now, in .45 APC (depending on the manufacturer), have I been introduced to copper-jacketed with exposed base lead......which, by convention, would not fit a category of "full" metal jacket....being called "FMJ."

And this all started with, "Do I need a gas check?" Oh, my.

[Marco Califo]

All bullets are that way. Jacketed, usually with that exposed patch, or, open tip bullets (Sierra MK, for example). Cast bullets were all lead, then plating bullets became popular to eliminate lead mist in the air at indoor ranges. These are elementary concepts most people pickup when they read their first reloading manual.
FMJ bullets have been required for military small arms since around 1900. They are "non-expanding" by virtue of the jacket. Read. Look at the pictures.

[Unclenick]

Cdoc42,

I think the source of the confusion is that "Full Metal Jacket" only applies to the part of the bullet you can see protruding from the case mouth of a loaded cartridge. It was meant to be used by soldiers to identify which jacketed bullets were allowed to be used in combat under the original interpretation of the Hague Accords. It never meant 100% bullet enclosure because the term was created when only the cup and core jacketing process existed, and there is no way to form a cup-based jacket 100% around a bullet. It is always open either at the base or at the tip, depending on whther the bottom of the cup became the tip or the base.