I’ve seen many discussions about using a higher grain bullet to achieve a higher sectional density for a given caliber as game size and/or toughness increases. Example, many would say use 130gr in your 270 Win when deer hunting but then recommend 150gr projectiles when using that same 270 Win for elk.

Couldn’t you achieve much the same by using a 130gr TSX which mushrooms less than let’s say a Partition? The face of a mushroomed TSX would have a smaller diameter than so despite being 20gr less it gives you a higher “Terminal sectional density”. I realize my example may not be mathematically correct (so please don’t crush me on that) but I’m just trying to illustrate the concept.

If this is valid I wonder if it would be better, to a point, to change bullet type instead of bullet grains for various animals. Keep in mind I’m talking in the range of pronghorn through moose and elk, nothing dangerous.

If a well designed bullet at 3100 fps. can break the near and far shoulders devastaing the tissue in between that's quite a bullet. If the same bullet can go in low and behind the shoulder rack havoc with the heart and lungs and exit the far side, well you be the judge. Well designed bullets like that do exist. Also heavy for caliber bullets can similarlly function roger

I think that setional density in momometal bullets is not as important as in a lead core or cup core bullets.In most hunting rifles if the right bullet is use for the game hunted.

Sectional density is a dynamic value once the bullet impacts. IOW, the frontal diameter is changing and so is the weight.

Some bullets like the Scirroco do not penetrate as far because the mushroom becomes so large it impedes penetration and can cause side slippage. You could say that it's sectional density is severely decreased and so is penetration. There are others like the TBBC, Interbond and A-Frame that are similar but do not mushroom quite as much as the Scirrocco.

The Nosler Partition is designed to lose the front part and the front petals fold against the shaft to form a small frontal diameter and it keeps going. Same with the Accubond. After it loses the front part and the petals fold back against the shaft, the sectional density goes up but still less than the original because of the reduced weight.

The TSX and other monometals do retain most if not all of their weight.

A lot also depends upon velocity and counterintuitively faster does not mean deeper. Reference these charts which are getting old but still hold some information that is useful





the Barnes X is shown in the 3rd graph, but keep in mind that these are bullets of the same weight. So if you are shooting a lighter monometal, the graphs perhaps would not show that it does as well as the others.

in a nutshell,theoreticly a more heavily constructed bullet would fill your requirments. but a sturdier bullet will produce a smaller wound channel and work correctly over a smaller range of velocities and game densities, that equates to unreliability just exactly what the manufacturers are trying to get away from.

Woods, is that your data or what is the source? It's very interesting but there are so many variables I wonder how accurate it can be. Thanks for posting the charts.

I don't care what books and magazines say...

I'll take sectional density any day over velocity....for terminal performance...

quote:

Originally posted by ForrestB:
Woods, is that your data or what is the source? It's very interesting but there are so many variables I wonder how accurate it can be. Thanks for posting the charts.

http://www.rathcoombe.net/sci-...listics/methods.html

It looks like the website has redone the graphs and I will have to study the new ones. It is also interesting to study the wound track graphs.

Thx for the feedback guys.

quote:

Originally posted by woods:

quote:

Originally posted by ForrestB:
Woods, is that your data or what is the source? It's very interesting but there are so many variables I wonder how accurate it can be. Thanks for posting the charts.

http://www.rathcoombe.net/sci-...listics/methods.html

It looks like the website has redone the graphs and I will have to study the new ones. It is also interesting to study the wound track graphs.

Thank you for giving this expose to us. What a lot of great work and reporting!!! Just loved it. roger

quote:

I realize my example may not be mathematically correct (so please don’t crush me on that) but I’m just trying to illustrate the concept.

Duck, your basic idea, ie, SD as a useful figure is obsolete because of today's wide variety of bullets with vastly variable construction is true.

SD was valid when all bullets were simple "cup and core" but that's no longer true, not for a looong time! SD ignores everything but diameter and weight. So that means a FMJ, RN, HP, Varmint, Target, Partition, solid copper, etc, bullet of a given caliber and weight are all projected to penatrate the same! Whoa!

I sure wish someone would jump on this. I would, simply because I think SD is relevant, but it's mostly opinion, and I don't want to argue today.

quote:

Originally posted by Kabluewy:
I think SD is relevant, but it's mostly opinion, and I don't want to argue today.

Hey Kabluewy, I agree with you except I'd change "it's mostly opinion" to it's a for sure absolute Fact.

It is still as relevant today as it has ever been. If an Expanding Solid(PCB) expands to too wide of a Diameter on Impact and remains in that same state, the SD drops to nearly nothing, and the penetration stops.

I'd imagine Jim C. will remember the penetration problems of the PCBs when they first came out once he thinks about it just a bit more. First there was no "reliable" expansion, so the PCBs were basically overly long FMJs. Then they went to over expansion and ripping off Petals(reducing the weight) which also caused the SD to drop. Now they seem to finally have the PCBs working about as well as they can be expected to work with the current designs.

But, the PCBs have yet to replace the Nosler Partitions which is the Gold Standard of Bullet performance.
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"I don't want to argue today." Doesn't seem to be anything to argue about, Facts are Facts.