Home Forums Reloading Big Game Rifles TTSX and E-tip.

I totally agree with you that SD is not the only factor in penetration, but it is definitely applicable. And the SD is simply the weight divided by the caliber, so frontal diameter isn't really even taken into account. That would be more of a surface area to weight calculation, and is definitely important, as you stated.

Huh? You just said density doesn't matter, but sectional density does. Okay, well since that is the case, even the much lower density marshmallow - strike that "absurd" example; let's use nylon instead- will still get the job done; it has so much more length to sacrifice before it quits. And, more importantly, since it has a much, much higher BC than lead, it will retain much more speed out at 500 yards than will the lead bullet.

And yes, in addition to density, hardness is another factor that matters, (but, just as with lead hitting steel, it isn't necessarily what we think it will be). While some may strive to apply numbers to what they see to make sense of it, using numbers to prove something that has not been seen can't always tell us what will happen.

I like to understand what I have seen. That doesn't, however, mean that one can use numbers to prove that something didn't actually happen. Two bullets went into a moose at a distance later measured to be 495 meters per the GPS. Neither came out and I recovered the one which I pictured eariler. Both were Barnes X bullets started at around 2900 fps at sea level. (I wasn't actually shooting over a chronograph when I shot the animal, but other ammo from the same batch had previously been measured.) The shots were fired at sea level. The temperature was in the 50s F. If those numbers help you crunch numbers to explain the "why," great.

The Barnes X bullet has always had a superior shape, with its hard pointed tip, over other (lead tipped) bullets. Just as I am not convinced that a polymer bullet would be superior in any way to a metal bullet, so too the plastic tipped TTSX adds nothing worthwhile to the bullet that it did not already have - except that it was added to make it open better, especially at lower speeds and longer distances. I do believe it it was designed to improve on problems the plain bullets sometimes have. I further think the MRX is evidence of that unspoken "need." And Barnes, who should know better where density is concerned, actually went better than lead (and the Winchester/Nosler FailSafe) by using an even denser tungsten matrix. Go figure.

BTW, back to the metal "splashes," rocks also do that when they are dropped into mud. Never seen any steam either (nor has burnt, or even cooked, meat been a problem in any game I have shot even when the bullet has completely come undone.) Heat is surely there in the energy transformation. It just isn't as much as some may think nor the only thing.

Again both Plates the AR-500 and the A-36 steel plates melt at the same temp. The only difference is that one plate is signifcantly harder than the other.
Take a center punch place it on the A-36 plate and hit it with a hammer (hard) the results will be a hole with displaced metal above the hole.. Take the same punch and place it on the AR-500 plate and hit it (hard) the plate will dull the punch with little to no indention the same as when a bullet hits it....
Inorder for a bullet to melt through a steel plate instantly the temp would certainly have to exceed 2000 degrees instantly and this certainly does not happen. If it did happen you could not touch the plate after shooting as the plate would be to hot and is certainly not the case

Frontal Diameter is the caliber... and, as the bullet expands this measurement increases. Also important to penetration is the lenght of the bullet after expansion. The longer the remaining shank is... the straighter (and ultimately deeper) the penetration is.

Sectional Density of a 30 cal. 180 grain bullet is .271.
If you take 180 and divied by .308 the answer is 584.4 is you divied 180 by 308 the answer is .5844.. No where close to the acctual Sectional Density of .271

This hammer and punch analogy is exactly what I was describing when I said that the bullet "pushes the steel" to the perimeter.

Klik,
I agree that ballistics models are complicated, and human beings probably don't understand them in their entirety.

However, when dealing with a hard material like copper, lead, or even a synthetic polymer, density has nothing to do with aerodynamics.

Aluminum is not very dense. If your theory were true, they would surely use something else to build jet planes, tungsten perhaps.

It rather get hit with a 180gr water ballon doing 2000fps than I would a 180gr Barnes TSX doing the same speed. YMMV.

I'm not sure where you get your ideas

Faulty anology. Planes fly. They are self propelled. In spite of their very great weight, jets do not reach maximum speed until they are well clear of the ground. Unpowered planes fall from the sky no less gracefully when they lose the speed needed for flight, than do bullets. Bullets are launched and slow the moment they leave the barrel, relying only on momentum.