I was surfing Google and came across this interesting article on subsonic ammo...

I really thought this was an interesting article, and some of you may find it interesting also... here is the link....
http://members.shaw.ca/cronhelm/SubsonicBullet.html



But one thing I thought was very interesting...

" Recently an LE issue Level 2 kevlar vest fell into our possession so we of course decided to shoot holes in it. We were a bit surprised to discover that .30 caliber subsonic rifle bullets are quite capable of penetrating level 2 body armour. Both 150gr FMJ and 200gr Lapua bullets penetrated the vest and an additional 16 plus inches of wet paper."

Kinda of an interesting note, on subsonic ammo...I don't have a real world use for it, but it is an example of where I have found that low velocity bullets, do still have quite an ability to deeply penetrate and do a lot of damage... which has a lot of hunting potential.. especially in thick woods or distance under 200 yds which is double the range most deer are taken in....

cheers
seafire

Indeed interesting! As is the claim made by some authorities, based on testing, that a low-velocity (1500-1600 FPS) solid bullet from a round like the .45/70 will out-penetrate similar bullets launched at higher (2200-2400 FPS) velocities.

Since this does not "stand to reason", the big-bore experts all "know better". They dismiss such assertions as "BS" ......

/

Certainly helps explain these graphs from http://www.rathcoombe.net/sci-tech/ballistics/methods.html

Always thought that it was entirely due to the bullet not expanding at the lower velocities but what Alf says makes a lot of sense.

roger Great stuff, Woods and Alf. Thank you.

Woods! Thanks for those charts! They're very useful.....

Mass (weight) counts.

A golf ball and a ping-pong ball are about the same diameter. But, unlike a golf ball, you can't throw a ping-pong ball fast enough to raise a knot on your big brothers head.

The penetration tests prove that it's hard to stop a flying boulder.

quote:

Originally posted by Woods:
Always thought that it was entirely due to the bullet not expanding at the lower velocities but what Alf says makes a lot of sense.

Hey Woods, First off, thanks for the Charts. They are extremely interesting and show a wealth of information for any Hunter.

Secondly, I can only give you 15% Credit on the above quote. You are correct that some specific Impact Velocity is indeed needed to create Expansion. And Totally Wrong about alf's post, in fact it is mostly full-of-beans - as usual.

Long ago I quit trying to discuss anything with alf, so I won't be doing that in this thread either. And I'll just give "one" example of how he has gotten it all - Wrong AGAIN!

quote:

Originally posted by alf:
The second part to the penetration isssue is the minimum energy density needed to breech the target. This is projectile shape and SD related.

To simplify my answer, that would be "Wrong AGAIN"!

In todays world, the Impact Velocity combined with the Expansion Design Envelope, the Material Components used in the Bullet and how the Materials are Combined are what create Penetration.

Many of the "old" Rules-of-Thumb are now obsolete unless you signify the specific Bullet being referenced. Reading old, dated literature and quoting from it(as alf always does) on what "used to be" no longer applies in all cases.
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It helps to look at the Charts and do a mental Linear Regression to smooooooooth out the Data Points into a Single Line.
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I find it very interesting that the Custom Bullets typically all run in the 19" to 12" of Penetration from about 2100fps and up. 7" spread over these Velocities.

Drop down to Premium Bullets and remove the Win Fail Safe. Now you see Penetration from 22" to about 17". Here a 5" spread. More consistent across the Velocity Range and a bit more Penetration that the Customs.

We will come back to the Win Fail Safe.

Next up are the Conventional Bullets. What absolutely amazing linearity. Penetration from 18" to about 10" for 8" across the IV. Extremely predictable and they nearly work as well as Clones of each other, even though the Designs are quite different.

And finally the Factory Commercial Bullets are also interesting. The Rem PSP and Win PP cut nearly identical Regression Lines.
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Now if we look at the good old(very old) Rem RN and compare it to the Win Fail Safe, you will see "Why!" the Win Fail Safe has been discontinued.

The good old Rem RN has always been a very "consistent" Bullet in predictable Penetration Linearity. Even in the very best Bullet Test ever performed in the civilian world (which can be found right here), the old Rem RN Design stands out as simply an outstanding Design.

Now if you go back to the Win Fail Safe, you will see that it Regresses into nearly a "U-shaped curve". It starts with no Expansion, then to the Expansion Stage and finally in to a Petal Shearing Stage where the Bullet becomes a Cylinder and resumes deeper Penetration.

This inconsistancy of the Win Fail Safe is what killed it off. Had the Designers had enough clout at Winchester, it would probably have never made it to the consumer market.

It did work well at "some" IVs, but not all of them. And, "Projectile Shape and SD"(that alf was Wrong about - as usual) had nothing to do with it.

The Win Fail Safe was killed off due to Penetration inconsistancy at various IVs created by the Expansion Design Envelope, the Material Components used in the Bullet and how those Materials were Combined.
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Absolutely amazing how well the:
Nosler B-Tip
Sierra GameKing
Hornady Interlock
Speer SPBT

are all so "consistent" and similar in Performance.

More interesting is that the Nosler partitions only vary 2-3 inches in penetration from 1650 fps to 3100 fps. That should tell a hunter something. The x bullet is similar only penetrates farther across the board. I think I could have predicted this with no charts. I am surprised the Hornady didn't do much better than the other conventional bullets, I wasn't surprised by the Speer bullets as I always considered them very soft.

Well, unfortunately it looks like Alf has withdrawn his post. But operating from memory (not one of my best qualities ), I remember a couple of analogies that made some sense.

Like jumping off the Golden Gate Bridge and the water being as hard as concrete because of the impact velocity, whereas jumping off a high dive into a swimming pool the water is a little softer. Makes me wonder whether the 200 pound suicide off the bridge or the 200 pound high diver penetrated deepest into the water.

Also, the spoon in the honey analogy where the faster you stir the more resistance you feel. Was still thinking about that cause it seems like the faster spoon is making more linear progress even though it is harder to push.

quote:

quote:
Originally posted by alf:
The second part to the penetration isssue is the minimum energy density needed to breech the target. This is projectile shape and SD related.

To simplify my answer, that would be "Wrong AGAIN"!

In todays world, the Impact Velocity combined with the Expansion Design Envelope, the Material Components used in the Bullet and how the Materials are Combined are what create Penetration.

All greek to me. Guess I need some definitions of minimum energy density (didn't know energy had varying density) and Expansion Design Envelope (did you make that up? ).

The first time I saw those charts they did create an epiphany for me in that it seems counter intuitive that the faster that a bullet hits something the less it penetrates (in the operating range of rifle projectiles).

HC, enjoyed your review of the charts but wonder about

quote:

Now if you go back to the Win Fail Safe, you will see that it Regresses into nearly a "U-shaped curve". It starts with no Expansion, then to the Expansion Stage and finally in to a Petal Shearing Stage where the Bullet becomes a Cylinder and resumes deeper Penetration.

since the Partition is supposedly designed to do the same thing, lose the front and form into a cylinder that continues penetrating. Maybe the Fail Safe had more of it's weight retained after shedding the petals so it penetrated further.

Anyway those charts were what sold me on Partitions and X bullets.

How about this chart

/

This is kinda like the old analogy...

I asked what time it was... not how to build a watch...

Hey Seafire, Totally forgot to mention that I really like SubSonic 22LRs. I've been using them for quite some time now on various Varmints I come across and they do work very well. I also appreciate the relatively mild report.

quote:

Originally posted by Woods:
All greek to me. Guess I need some definitions of minimum energy density (didn't know energy had varying density) and Expansion Design Envelope (did you make that up?).

Hey Woods, Without me telling you the answer, when you read alf's response to your question about Energy Density, do you think it applies to any of the Bullets in your Chart(s)? If so, which one(s) and why?

Do you think ANYTHING is missing in his definition?
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The "Expansion Design Envelope" is clearly seen in the last Chart you posted. It is one portion of Bullet Design. We can skip over the "before Impact" considerations and go directly to what happens immediately upon, or closely following, Impact. Then(in Expanding Bullets) you are concerned with the Rate of Expansion, the degree of Expansion, the amount of retained Expansion, Weight Retention, Stability and Penetration for a quick partial list. None of that should be Greek to you.

If we look at one of your old favorites in this last Chart, the 180gr Nosler B-Tip, you can see how it meets each of those criteria.
1. The Plastic Tip makes Impact and begins a rapid initial(but partial) Expansion of the Bullet's Nose.
2. Then you can see where the actual Nose portion of the Bullet begins Expanding(on it's own) at a smooth and steady rate until MAX Expansion is reached.
3. At MAX Expansion(the widest point in the cavity-trace), there is a sudden collapse of those "Petals" as they rapidly fold back.
4. Lead is wiped away from the exposed core and the Profile is reduced a bit more in diameter.
5. It reaches it's final shape and continues ahead until all the remaining Dynamic Energy is expended and stops.

That is the Expansion Design Envelope for the B-Tip and the Chart shows how it goes about doing it's business quite well.

quote:

Originally posted by Woods:
since the Partition is supposedly designed to do the same thing, lose the front and form into a cylinder that continues penetrating. Maybe the Fail Safe had more of it's weight retained after shedding the petals so it penetrated further.

I'm not sure how much weight was typically retained by the Win Fail Safe, so I can't address that without guessing. What we know for sure is that the Fail Safe was not a Bullet that Expanded in a predictable way and once it did Expand, it often completely lost it's Petals which in turn caused it to become a Solid Cylinder.

As the Petals break off, they appear to do it sometimes all at once and sometimes they loose a couple and begin tumbling. Then the other Petals may or may not break off, just a bit unpredictable.

The Partition has a great reputation for consistant predictable Expansion, it retains some of the Expanded Profile(typically 40%-50% Retained Expansion) as it moves forward, and typically retains 60% of it's original weight to carry the Dynamic Energy forward. It is also important to understand the "consistant" way the Partition Expands allows it to have great Stability which tends to keep it moving in a straight line through the Game - without tumbling.
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For a final gut-buster, let me pull this quote before alf erases it:

quote:

Originally posted by alf:
A picture of a bust up bullet taken from a stack of telephone directories looking like the same dug up from a roadkill deer tells us absolutely nothing about how that bullet performed in living tissue. ...

Feel free to quote me on

quote:

Originally posted by Hot Core:
Hey Woods, Without me telling you the answer, when you read alf's response to your question about Energy Density, do you think it applies to any of the Bullets in your Chart(s)? If so, which one(s) and why?

Do you think ANYTHING is missing in his definition?

OK, I'll play. It doesn't apply to any of them because they all have sufficient energy to penetrate at the velocities shown in the chart. Seems to me that I don't see any allowance for the hardness of the surface they are trying to penetrate.

This all kinda gives someone ammunition (pardon the expression) that a magnum loudenboomer is not all it's cracked up to be. Considering that a 30-06 shooting a 180 gr Interlock would penetrate at least 3" more at 300 yards than a 30-378.

Hey Woods, I'll PM you so the embarrassment for alf does not have to continue.