130 gr TTSX

Momentum is not a measure of a bullets ability to perform work (penetration and the displacement of target or animal matter) rather momentum is a vector that is best used to determine how a bullet will react on a hard and instantaneous impact.....Such as a steel silhouette target, gong, or bone.......
Momentum has no bearing on a bullets slow deceleration into meat or expansion test media. It does have a significant representation where it comes to smashing large bones and the devastation this creates.....Something to consider when hunting large game.

To prove the physics involved shoot both a 243 100 grain(3200 fps) and a trapdoor loaded 45/70 400 grain (1400fps) at a heavy steel gong. The 243 has more kinetic energy, but the observed impact is significantly greater with the slow 405gr.
I have also observed this phenomenon with a 375 using 235 and 300 grain bullets as well as with my 416 with 300grs vs 400's. The 416 actually had less energy with the 400grain load than the 300 yet it absolutely rocked the gong....

Kinetic energy is a completely different calculation that is used in an attempt to describe the work capabilities (horsepower) of a moving projectile. The formula can not make allowances for bullet construction, but it does have some relevance as a guideline.



Light X-bullets are nothing new and to be honest I used to advocate them.
I shot quite a bit of game with 160 and 175gr .338's, some 210gr 375's as well as quite a few .416 300 grainers.
I had a few bullets steer significantly off course (in the animal), but everything died shortly after being introduced to Mr Barnes.


As hunters we are pretty obsessed about the long shots. For many of us our practice revolves around the long shot so we can perform when the time comes. When I'm moose hunting from a truck I even carry a monster long shot rig (almost 20 pounds), and the associated equipment in the back seat.....That moose is in real trouble far (FAR) away.
In reality unless you look for it, a real long shot is a pretty rare thing and when it comes the average hunting rifle setup is not ideal for shots much over 350yards. I choose a bullet accordingly.

These days I also like the margin for error that a slightly heavier for caliber bullet offers. Randy Barnes himself recommends the 165grain X for Elk hunting...Should tell you something.

Sorry didn't mean to write a book!:redface:
 
Gate I have 9 different calibers and 33 different bullet weights that I want to test! Total bill to buy just one box of each type/weight bullet I want to test is $1560!

I already own half the stuff but I need to drop $750 to buy the various bullets I am interested in testing.

I had the engineering student work out theoretically what the 500gr .458 Lott bullet should penetrate in the paper test. According to his calculator... 37", at 2235fps MV. It will be interesting to see what reality is. Theory and fact are often quite different.



Check this article out. It's about as good an article as you will find regards
penetration testing and bullet evaluation.

www.rathcoombe.net/sci-tech/ballistics/methods.html
 
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Omega said:
I still don't follow. You can develop momentum numbers for any and all bullet weights shot from any gun through the formula. Momentum= mass x velocity / gravity constant (32.1729). Where does pressure figure into it? Or what inequality does it create not having the same pressure? It is like saying that all the weights of bullets have to be fired at the same velocity to be compared.
Click to expand...

Pressure comes into play when you try to determine the optimum velocity of bullets of differing weight, if the comparison is to valid. If both bullets are fired at the same velocity, the heavier bullet wins regardless of any other consideration. But if the light bullet is fired as fast as it possibly can be, while the heavy bullet is fired at a velocity half as fast as is possible, the light bullet wins. The only way to balance this is to fire both bullets at equal pressure through barrels of identical length and internal dimensions. If one barrel is tight or if one barrel is loose, the results of the comparison fall into question.
 
X-fan said:
Momentum is not a measure of a bullets ability to perform work (penetration and the displacement of target or animal matter) rather momentum is a vector that is best used to determine how a bullet will react on a hard and instantaneous impact.....Such as a steel silhouette target, gong, or bone.......
Momentum has no bearing on a bullets slow deceleration into meat or expansion test media. It does have a significant representation where it comes to smashing large bones and the devastation this creates.....Something to consider when hunting large game.

To prove the physics involved shoot both a 243 100 grain(3200 fps) and a trapdoor loaded 45/70 400 grain (1400fps) at a heavy steel gong. The 243 has more kinetic energy, but the observed impact is significantly greater with the slow 405gr.
I have also observed this phenomenon with a 375 using 235 and 300 grain bullets as well as with my 416 with 300grs vs 400's. The 416 actually had less energy with the 400grain load than the 300 yet it absolutely rocked the gong....

Kinetic energy is a completely different calculation that is used in an attempt to describe the work capabilities (horsepower) of a moving projectile. The formula can not make allowances for bullet construction, but it does have some relevance as a guideline.



Light X-bullets are nothing new and to be honest I used to advocate them.
I shot quite a bit of game with 160 and 175gr .338's, some 210gr 375's as well as quite a few .416 300 grainers.
I had a few bullets steer significantly off course (in the animal), but everything died shortly after being introduced to Mr Barnes.


As hunters we are pretty obsessed about the long shots. For many of us our practice revolves around the long shot so we can perform when the time comes. When I'm moose hunting from a truck I even carry a monster long shot rig (almost 20 pounds), and the associated equipment in the back seat.....That moose is in real trouble far (FAR) away.
In reality unless you look for it, a real long shot is a pretty rare thing and when it comes the average hunting rifle setup is not ideal for shots much over 350yards. I choose a bullet accordingly.

These days I also like the margin for error that a slightly heavier for caliber bullet offers. Randy Barnes himself recommends the 165grain X for Elk hunting...Should tell you something.

Sorry didn't mean to write a book!:redface:
Click to expand...

I'm not sure that your assertion of a bullets ability to penetrate tissue is not a function of momentum, but perhaps I misunderstand the concept.

Lets consider the steel gong for a moment. A bullet's ability to penetrates steel is a function of velocity and little else. If I fire a conical shaped charge over a 4" block of armored steel, a clean hole is driven through the steel by powdered glass or metal particles that by themselves are almost too light a mass to measure but do wonderous things at 6 km/sec. If we take a .50 caliber round that drives a 650 gr bullet at 3000 fps, it will punch through a 1" mild steel plate hanging on a chain and the plate will barely move. If we were to shoot the same plate with a 150 gr .30/30 bullet, it will bounce dramatically on the end of the chain. Does this mean that the .30/150 has more momentum than the .50/650?

If the bullet's ability to penetrate through tissue is not a function of momentum, I'll concede that I might use the terms incorrectly. My observations however are that when two bullets of similar structure but different weights when driven at equal pressure from the same rifle, penetrate equally.
 
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Boomer said:
Pressure comes into play when you try to determine the optimum velocity of bullets of differing weight, if the comparison is to valid. If both bullets are fired at the same velocity, the heavier bullet wins regardless of any other consideration. But if the light bullet is fired as fast as it possibly can be, while the heavy bullet is fired at a velocity half as fast as is possible, the light bullet wins. The only way to balance this is to fire both bullets at equal pressure through barrels of identical length and internal dimensions. If one barrel is tight or if one barrel is loose, the results of the comparison fall into question.
Click to expand...

Gotchya thanks, I was headed in another direction.
 
]
Demonical said:
Gate I have 9 different calibers and 33 different bullet weights that I want to test! Total bill to buy just one box of each type/weight bullet I want to test is $1560!

I already own half the stuff but I need to drop $750 to buy the various bullets I am interested in testing.
Click to expand...


have fun:)





I
had the engineering student work out theoretically what the 500gr .458 Lott bullet should penetrate in the paper test. According to his calculator... 37", at 2235fps MV. It will be interesting to see what reality is. Theory and fact are often quite different.
Click to expand...

No need to test it- I'll tell you rigth now that a 500gr bullet froma 458 Lott should crush anything you point it at.:)
 
Boomer said:
That might be the theory, but it doesn't square with real world shooting. Provided I shot bullets of similar construction, penetration was always similar when fired at similar pressure from the same rifle at the same range, despite widely different SD and impact velocity.

When you calculated for mass you neglected to divide by the velocity of gravity, so your numbers are off a bit.
Click to expand...


All I am saying is that you cannot load the lighter bullet to a high enough velocity because you will be way over max pressure. The reason, I suspect, is that pressure and velocity do not increase proportionally.

Regarding your second point. Gravity does not have velocity. Gravity exerts a force. This force causes an acceleration of 9.8 m/s².

Like I said, none of it (in my opinion) really matters. The only point I was trying to make is that if you load a heavy bullet to maximum pressure, you will not be able to attain the same momentum out of a smaller bullet (in the same cartridge/rifle) because you will not be able to propell the smaller bullet fast enough.

Another easy way to look at it is this. Changes in momentum are directly proportional to changes in mass and/or velocity. A 180 gr bullet
is 38.5% heavier than a 130 gr bullet. Therefore you need a 38.5% increase in velocity to make up for the lighter bullet.

I used to really enjoy classical physics, so I like these kinds of topics. The way GH says it is the only thing that matters. If an unknown bullet compares favourably to a known, in similar test situations, then it should perform similarly to the known bullet on game.

In other words GH wanted to test the bullet on paper, not game. Now he KNOWS it will be ok on game. In this way he has shown respect to his quarry.
 
I would like to see the same bullet test at different distances 100, 200, 300 yards I'm thinking that the 130gr bullet once it gets out to the longer distances will not penetrate as well as the heavier slower bullets.

Come on someone prove me wrong not with math/theories but with actually shooting at those distances.

I guess I am still a believer in fast heavier bullets which is why I went up in case size to the RUM's...

:popCorn:
 
1899 said:
Regarding your second point. Gravity does not have velocity. Gravity exerts a force. This force causes an acceleration of 9.8 m/s².
Click to expand...


OK, so 9.8 mps translates to 32.152 fps/sec which over the duration of one second is 64.3 (I use 64.284). The bullet weight in pounds must be divided by 64.3 to equal mass.

The mass of a 130 gr bullet therefore is .00029 and the mass of the 180 is .0004. If you multiply both of those numbers by the square of their respective velocity I think you'll find the results quite similar.
 
I'm thinking that the 130gr bullet once it gets out to the longer distances will not penetrate as well as the heavier slower bullets.
Click to expand...

I thought this explained it...
 
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Boomer said:
OK, so 9.8 mps translates to 32.152 fps/sec which over the duration of one second is 64.3 (I use 64.284). The bullet weight in pounds must be divided by 64.3 to equal mass.

The mass of a 130 gr bullet therefore is .00029 and the mass of the 180 is .0004. If you multiply both of those numbers by the square of their respective velocity I think you'll find the results quite similar.
Click to expand...

You are correct with the conversion of weight to mass. Good eye on that error! But I think the answer will change proportionally for both.


On the second point: If you multiply both by .5 and the square of their velocity you get kinetic energy. In that case the smaller bullet has an advantage because the velocity is squared, and that is why the kinetic energy will be similar. I believe this was a marketing ploy used by firearms/ammunition manufacturers: If you use kinetic energy the smaller bullet looks very good compared to a larger slower bullet. So if you are saying that the kinetic energy will be similar for the same pressure different weight bullets, then yes, it could be.
 
1899 said:
You are correct with the conversion of weight to mass. Good eye on that error! But I think the answer will change proportionally for both.


On the second point: If you multiply both by .5 and the square of their velocity you get kinetic energy. In that case the smaller bullet has an advantage because the velocity is squared, and that is why the kinetic energy will be similar. I believe this was a marketing ploy used by firearms/ammunition manufacturers: If you use kinetic energy the smaller bullet looks very good compared to a larger slower bullet. So if you are saying that the kinetic energy will be similar for the same pressure different weight bullets, then yes, it could be.
Click to expand...

I think kenetic energy is what happens when you smak a gong or a ballistic pendulum, but not what happens as a bullet penetrates through a solid or liquid medium. My observations have been that bullets of different weights penetrate to a similar depth provided that, as I mentioned before, certain conditions exist. I've put this down to momentum, but perhaps I have used the wrong term, high school was a long time ago.
 
Boomer said:
I think kenetic energy is what happens when you smak a gong or a ballistic pendulum, but not what happens as a bullet penetrates through a solid or liquid medium. My observations have been that bullets of different weights penetrate to a similar depth provided that, as I mentioned before, certain conditions exist. I've put this down to momentum, but perhaps I have used the wrong term, high school was a long time ago.
Click to expand...

The problem is that there are so many variables: rate of bullet expansion, frontal area, position of center of mass (I think the more forward the center of mass the more likely the bullet will travel straight), consistancy of the ballistic medium from shot to shot etc etc etc.

That is why the "GH method" is good. I think all of us agree that a .30 cal. 180gr Nosler Partition at 2700 fps will kill moose, deer and elk dead. Therefore a bullet of similar diameter that has similar performance on the test medium should have similar results on game, irregardless of the weight and velocity.

And yes, high school was a long time ago!

The only downside I see is the dry newsprint, because it is VERY tough and therefore minimizes differences. For example, what would 1" of dry newsprint penetration equate to in wet newsprint?
 
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