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  #91  
Old 12-06-2018, 05:40 PM
Xbolt7mm Xbolt7mm is offline
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Originally Posted by AndrewM View Post
For those that want to skip the read:
Pressure P is a force F per area A
P = F / A.
The change in energy of a system dE is the force exerted on the system (in this case the projectile) times the distance over which the force is exerted dx
dE = -F dx
where the minus sign indicates the force is in the opposite direction of the projectile motion, so that its energy is being reduced. For penetration of a thick target to occur, we need the pressure to equal the cavity strength
P = Yc.
Combining these relations, we find
dE = Yc A dx.
Since this relation is linear, if we know the energy E of the projectile when it initially hits the target, we can easily find the distance penetrated xp
xp = E / (Yc A).
For the purpose of this discussion, we can ignore the potential energy of the projectile, so that its energy is given by its kinetic energy alone
E = ½ m v²
where m is the projectile mass and v is its speed. We now have
xp = m*v²/(A*2*Yc)
SD=m/A
xp=v²*Yc*2*SD
SD and YC are constant. Velocity is not so penetration is not constant. It has a quadratic relationship with velocity.
Lmao....this post was awesome,,, I do not have ability dispute it or agree with it but SC said noting about the information, thx Andrew lol
  #92  
Old 12-06-2018, 05:42 PM
Salavee Salavee is offline
 
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Originally Posted by Kurt505 View Post
I would ask Stinky but you’re the one who brought it up.

I agree with you, energy is there, trust me I know the formula off by heart and have for used for 20 yrs. air guns archery and firearms ballistics, I gauge a bows efficiency by how many ft/lbs I get on the arrow compared to pull draw weight, I have acutely compaired pellet energy and velocity for a long time and on small game also...it’s the same there, the .177 vs .22 debate is eternal, speed vs energy...I got you man.👌
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I don’t really want the answer, I’m just trying to make a point.

Ps, Andrew has way better formulas imo.
Yeah .. I think he does too.
NO, it was a Hoyt somthin or other. They make difference,you know
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  #93  
Old 12-06-2018, 05:58 PM
Salavee Salavee is offline
 
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Originally Posted by Xbolt7mm View Post
Lmao....this post was awesome,,, I do not have ability dispute it or agree with it but SC said noting about the information, thx Andrew lol
For sure he will dispute those formulas. the're too old.
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  #94  
Old 12-06-2018, 05:59 PM
Stinky Coyote Stinky Coyote is offline
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Originally Posted by Salavee View Post
I'm spooked by anybody that utters the "trust me" thingy.

I learned from my "professor" that an arrow delivers very little enegry to it's target, Matter of fact he indicated an arrow is driven through it's target by a force called Momentum and imparts little, if any, energy to the target. It kills by cutting,not energy transfer.
Should I sue him for lying to me ?.
Maybe? You call it momentum I call it sd. End of day it’s still frontal area x mass. Bit tricky to calculate on the Broadhead alone but the heavier arrow from same bow goes slower so it stops slower and the sd is higher so that helps it go deeper too, no expansion there. I believe Andrew pointed out a quadratic relationship? I love that btw, sounds about right for that increase in velocity to penetration and also recoil energy vs impact energy...inefficient and largely useless figures but that’s a good term to help explain it.😉
  #95  
Old 12-06-2018, 06:05 PM
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I usually try to stay out of debates and just come for advice. These this vs that threads drive me nuts when I see false or misleading information. I imagine a pile of people come here for advice as well and would have to see someone sell their Grandpa’s rifle or family heirloom because they think it won’t kill!
  #96  
Old 12-06-2018, 06:09 PM
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Originally Posted by Stinky Coyote View Post
Maybe? You call it momentum I call it sd. End of day it’s still frontal area x mass. Bit tricky to calculate on the Broadhead alone but the heavier arrow from same bow goes slower so it stops slower and the sd is higher so that helps it go deeper too, no expansion there. I believe Andrew pointed out a quadratic relationship? I love that btw, sounds about right for that increase in velocity to penetration and also recoil energy vs impact energy...inefficient and largely useless figures but that’s a good term to help explain it.😉
Momentum is not frontal area x mass and neither is SD. Lol
  #97  
Old 12-06-2018, 06:55 PM
Don_Parsons Don_Parsons is offline
 
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Quote:
Originally Posted by Stinky Coyote View Post
I agree with you, energy is there, trust me I know the formula off by heart and have for used for 20 yrs. air guns archery and firearms ballistics, I gauge a bows efficiency by how many ft/lbs I get on the arrow compared to pull draw weight, I have acutely compaired pellet energy and velocity for a long time and on small game also...it’s the same there, the .177 vs .22 debate is eternal, speed vs energy...I got you man.👌

Now all of a sudden energy is a factor.

What's going on SC, how come that's its one way for this,,, but not that way for that.

Just asking since your sharing in mixed messages now.
  #98  
Old 12-06-2018, 07:19 PM
bitterrootfly bitterrootfly is offline
 
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Quote:
Originally Posted by Don_Parsons View Post
Now all of a sudden energy is a factor.

What's going on SC, how come that's its one way for this,,, but not that way for that.

Just asking since your sharing in mixed messages now.
The great thing about the initial posts in these 6.5 vs ___ threads is how closely they adhere to an old statistic adage. “What is revealed is interesting, what is covered up or omitted... crucial.”
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  #99  
Old 12-06-2018, 07:51 PM
Salavee Salavee is offline
 
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Originally Posted by Stinky Coyote View Post
Maybe? You call it momentum I call it sd. End of day it’s still frontal area x mass. Bit tricky to calculate on the Broadhead alone but the heavier arrow from same bow goes slower so it stops slower and the sd is higher so that helps it go deeper too, no expansion there. I believe Andrew pointed out a quadratic relationship? I love that btw, sounds about right for that increase in velocity to penetration and also recoil energy vs impact energy...inefficient and largely useless figures but that’s a good term to help explain it.😉
Momentum is a motion, so how do you associate with that with a bullets SD ?
SD refers to Total Bullet weight and diameter, so it has no momentum. Gad Man ! you're a real piece of work

Tell me how you measure the SD of an arrow without a form factor, or do you have a secret ?

Gad Man ! you're a real piece of work.
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  #100  
Old 12-06-2018, 08:06 PM
bitterrootfly bitterrootfly is offline
 
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Just as relevant as all these formulas are the physics laws they represent, one of importance here is the law of conservation of momentum. In any collision (of which a bullet impacting a target is one) momentum is conserved therefore greater the momentum, greater the opposition and greater the internal damage. In addition to conserve a higher momentum, more work must be done against a projectile which in turn translates to a bullet with a higher momentum being more difficult to bring to a halt or to slow down, it is in these applications that the larger and equally as fast projectiles shine. Energy matters, you kid yourself if you say otherwise. Does it matter more than SD or impact velocity? Maybe, maybe not, it’s hard to judge... but energy certainly isn’t irrelevant.
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  #101  
Old 12-06-2018, 08:08 PM
Stinky Coyote Stinky Coyote is offline
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Quote:
Originally Posted by Salavee View Post
Momentum is a motion, so how do you associate with that with a bullets SD ?
SD refers to Total Bullet weight and diameter, so it has no momentum. Gad Man ! you're a real piece of work

Tell me how you measure the SD of an arrow without a form factor, or do you have a secret ?

Gad Man ! you're a real piece of work.
Did that for you as you keep getting it mixed up. You keep calling it that so I’m just going with you a bit. At game, so much catching up to do, will be a couple days, have patience.😉
  #102  
Old 12-06-2018, 08:19 PM
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Originally Posted by Stinky Coyote View Post
Did that for you as you keep getting it mixed up. You keep calling it that so I’m just going with you a bit. At game, so much catching up to do, will be a couple days, have patience.😉
You love attention, regardless of how negative it is
  #103  
Old 12-06-2018, 08:28 PM
Salavee Salavee is offline
 
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For sure. I'm all mixed up.. tring to follow your math and BS
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  #104  
Old 12-06-2018, 08:53 PM
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I was hoping SC would fill us in on how these numbers add up when there are differences in the equations now,,, all of us we're on track until he changed his mind over the energy thing.

It was one thing one day,,, now tonight the story changes.

Oh well, the rest of us will still be here if you choose to join in on the good times.

Tonight I get to brush up on kinetic energy, things in motion stay in motion, and the 308 Grand Slam 180gr bullets.

They work awesome in our rifles with slow ft-per seconds. Semi pointed round noise that dump energy fast as they grind work their way into the vitals of those thick skins. Ha

35 year track record of harvesting critters all around the world,,, purhaps this is where the name came from.
  #105  
Old 12-06-2018, 08:54 PM
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6.5 cal TTSX fired from the east, 30 cal TTSX fired from the west, both have the same sectional density and velocity, they hit each other head on perfectly, which one wins?
  #106  
Old 12-06-2018, 09:19 PM
Xbolt7mm Xbolt7mm is offline
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Originally Posted by Bushrat View Post
6.5 cal TTSX fired from the east, 30 cal TTSX fired from the west, both have the same sectional density and velocity, they hit each other head on perfectly, which one wins?
BOOM!!!!! There it is,, we have a winner!!!!
  #107  
Old 12-06-2018, 09:32 PM
Kurt505 Kurt505 is offline
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Originally Posted by Xbolt7mm View Post
BOOM!!!!! There it is,, we have a winner!!!!
No, they are not hitting equal targets.

Yes the heavier 30cal will win but it’s hitting a lighter target so it’s not a fair comparison. Not that I care, I just thought I’d point that out.
  #108  
Old 12-06-2018, 09:36 PM
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No, they are not hitting equal targets.

Yes the heavier 30cal will win but it’s hitting a lighter target so it’s not a fair comparison. Not that I care, I just thought I’d point that out.
You kill me there flip flop
  #109  
Old 12-06-2018, 09:37 PM
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Originally Posted by Kurt505 View Post
No, they are not hitting equal targets.

Yes the heavier 30cal will win but it’s hitting a lighter target so it’s not a fair comparison. Not that I care, I just thought I’d point that out.
I think the point is one hits with more force
  #110  
Old 12-06-2018, 09:38 PM
Jeron Kahyar Jeron Kahyar is offline
 
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Originally Posted by Kurt505 View Post
No, they are not hitting equal targets.

Yes the heavier 30cal will win but it’s hitting a lighter target so it’s not a fair comparison. Not that I care, I just thought I’d point that out.
Are you saying the heavier 30 cal has more of something to make it win this bout?
  #111  
Old 12-06-2018, 09:51 PM
Kurt505 Kurt505 is offline
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You kill me there flip flop
Explain yourself there yap yap, you’re not making any sense.
  #112  
Old 12-06-2018, 09:53 PM
Nyksta Nyksta is offline
 
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Explain yourself there yap yap, you’re not making any sense.
Dont change the subject kurt
  #113  
Old 12-06-2018, 10:02 PM
Kurt505 Kurt505 is offline
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Originally Posted by Jeron Kahyar View Post
Are you saying the heavier 30 cal has more of something to make it win this bout?
No, I just went and re-read my post, I didn’t say the 30 cal has more of something.
  #114  
Old 12-06-2018, 10:04 PM
Kurt505 Kurt505 is offline
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Dont change the subject kurt
I didn’t. Please explain what it is you’re talking about because I have no clue. And while you’re at it, quote me on here to show me what exactly you want to argue with me about.
  #115  
Old 12-06-2018, 10:12 PM
Jeron Kahyar Jeron Kahyar is offline
 
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Originally Posted by Kurt505 View Post
No, they are not hitting equal targets.

Yes the heavier 30cal will win but it’s hitting a lighter target so it’s not a fair comparison. Not that I care, I just thought I’d point that out.
Quote:
Originally Posted by Jeron Kahyar View Post
Are you saying the heavier 30 cal has more of something to make it win this bout?
Quote:
Originally Posted by Kurt505 View Post
Explain yourself there yap yap, you’re not making any sense.
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Originally Posted by Kurt505 View Post
No, I just went and re-read my post, I didn’t say the 30 cal has more of something.
Okay I see that I can not imply anything and expect you to get the point.

Your statement says that the light 6.5mm bullet is not hitting an equal target, the 30cal heavy bullet. You with me so far?

I replied implying that you have stated an obvious imbalance. This shows that there is more of something one one side of the collision than the other. This implication being the 30cal is carrying more energy.

I am now explaining myself so hopefully you can figure it out this time around. Do you now understand what was said about the 30 cal having more energy?
  #116  
Old 12-06-2018, 10:15 PM
Kurt505 Kurt505 is offline
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Well nyksta....... what exactly is it I said that you or xbolt figure I’m flip flopping on??? Or are you just jumping on an unmanned wagon? Lol!
  #117  
Old 12-06-2018, 10:30 PM
Kurt505 Kurt505 is offline
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Originally Posted by Jeron Kahyar View Post
Okay I see that I can not imply anything and expect you to get the point.

Your statement says that the light 6.5mm bullet is not hitting an equal target, the 30cal heavy bullet. You with me so far?

I replied implying that you have stated an obvious imbalance. This shows that there is more of something one one side of the collision than the other. This implication being the 30cal is carrying more energy.

I am now explaining myself so hopefully you can figure it out this time around. Do you now understand what was said about the 30 cal having more energy?
I assumed pretty much anyone capable of reading this thread would have the common sense to know a bowling ball is going to beat a baseball in a head on. If it’s a comparison of penetration however, this type of test would prove nothing, all it proves is that a heavier object will beat a lighter object in a collision. For the test to be equal it should be a 5lb bowling ball vs like a 7lb bowling ball though.

If I throw a 15lb bowling ball at a moose and a 10lb spear at a moose, which one will have more penetration? If I throw them at each other, which one will win? Two of the same test subjects in two different tests with two different winners.

To be clear, re-read through this entire thread and see how many times I said I agreed with th op, I think because of my understanding of ballistic coefficients and how they transfer energy down range, some people are getting it confused with being a fanboy of a certain cartridge and want to argue for argument sakes.
  #118  
Old 12-06-2018, 10:31 PM
Salavee Salavee is offline
 
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No, they are not hitting equal targets.

Yes the heavier 30cal will win but it’s hitting a lighter target so it’s not a fair comparison. Not that I care, I just thought I’d point that out.
what if the lighter bullet has a higher SD?.. just thought I'd ask
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  #119  
Old 12-06-2018, 10:34 PM
Stinky Coyote Stinky Coyote is offline
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Originally Posted by Don_Parsons View Post
The artical posted had some Intresting information on the 1998 test.

How come both arrows only penitrad the hard steel plate 0.84 mm and 1.8mm as the 22 rimfire left a 3.3 mm dint.

Dam,,, and here I though my arrows had way more punch then my 22.

The 50 caliber BMG had the deepest dints in the hardened steel plate of 14mm and 29mm into the armor piercing plate.

Purhaps energy does play a roll after all.

Who would though that. Ha
It plays a part, just an insignificant part. Not a calc worthy of including as important. You must impart energy to the bullet to give it velocity. Ie, 61,000psi explosion slap in the azz kind of thing.

The you see the greater energy on the steel dimples...but was the steel still dimpled? Arrows can kill as fast as bullets, an arrows sd is through the roof, that’s why it only takes a 2-300 fps to drive deep or deeper than bullets. I did a quick sd calc of 385 gr arrow, .281” diam and its .697...keeping in mind the velocity is so low that that compounding resistance at 250-300 fps is nothing compared to 2500 fps, arrow likely goes deeper than most bullets.

Might be a bit of a mind job to get around it but the same principles apply to different weight arrows out of same bow, the heavier one has higher sd, now way around it. It goes deeper. Same force drove the two arrows. One went faster yet shallower, other slower but deeper. Two factors that did that, sd and less compounding resistance to the lower velocity.
  #120  
Old 12-06-2018, 10:34 PM
Kurt505 Kurt505 is offline
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what if the lighter bullet has a higher SD?.. just thought I'd ask
Then it’s possible it will destroy the heavier bullet. Common sense.


130gr copper bullet flying east vs 220gr lead bullet flying west, who wins?

Last edited by Kurt505; 12-06-2018 at 10:39 PM.
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