xsn10s
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That's why many of the serious shooters left here.
Seems to be a lot of this going on
Bullet Construction vs Lethality
- Thread starter nralifer
- Start date
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xsn10s
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Hmm well it sure looks like you could be shooting across a road at 1377 yards according to google maps. And there's a house right near that path too. Wowie.
A/1-61
Well-Known Member
I have no problem with a quartering away shot. Very lethal when you can slip a bullet behind the facing shoulder. I was commenting on the original comment in this thread, " any angle"
There is no house in the shooting lanes we are all neighbors and we all shoot so you keep the wowies for your buddies, you are just making foolish assumptions about an area you know nothing about,
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xsn10s
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I'm just calling it like I see it on google maps with the address you provided. Happy hunting.
RockyMtnMT
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So it looks like we can now talk about what the OP started the thread to talk about. Bullet material and how it effects terminal performance. Brian an I entered into this bullet making thing as hunters looking for a better bullet for hunting. All based around terminal performance. We wanted a bullet that would make our game nice and dead without destroying a bunch of meat. In our quest we found copper bullets and preferred them to lead bullets because of less meat damage. We use quite a few different ones but found issues that we didn't like with each that we tried. We based our design on the findings of Rathcoombe (Shooting Holes in the Wounding Theory). https://rathcoombe.net/sci-tech/ballistics/politics.html We set out to make a bullet that would do what his physics paper described. In our naivety, we did not thing this would be hard to do. Just get the most pure copper available and it would work. It did not. Here we sat with a lathe in my garage and our first bullets (with great bc) worked great, as long as we kept the impact vel above 2500 fps. We had our website ready to launch after our first hunting season with Hammers with truck loads of game taken and stellar results and fortunately figured out the problem with our material and design. Had we launched at that point we would have failed shortly after. We assumed so much and most of those assumptions were wrong. We redesigned and moved to a different copper that worked better but still didn't do what our ideal was. We needed to get to market and went ahead with the best that we could find at the time. We continued to try other coppers, at great expense because you could only get them at 1000 lbs at a minimum order. So, yes to a question earlier, we tried copper that would retain all of it's weight and we tried brittle copper. High weight retention does not create the stunning impacts of a bullet that sheds weight. Brittle copper was very velocity dependent on how it would retain its weight. This results in a narrow window of impact velocity that works well. Thousands of pounds of copper was recycled, at a large expense, when we found the copper that we currently use. We are able to shed the desired weight, in a controlled manner, through about a 3000 fps range of impact velocity and maintain a flat front retained shank that varies only a few grains regardless of impact velocity. We were able to get a foundry to hold the tight tolerance in the alloy that we use, enabling us to be successful in our quest to make the bullet that Rathcoombe described. Without the foundries work to hold the tolerance that we need, we would not be able to achieve the high expectations that we have for what a bullet should do for terminal performance. The only thing in our production that we are tight lipped about is the raw material that we use. It is what separates our on game performance from all the others.
We will see if the thread can maintain the material and performance discussion that the OP wanted. If so, I would love to continue further into hunting bullet terminal performance.
We will see if the thread can maintain the material and performance discussion that the OP wanted. If so, I would love to continue further into hunting bullet terminal performance.
Thanks for the info, Steve. You answered my question.
nralifer
Well-Known Member
I don't know what altitude you were at shooting the 124HH bullet from your 300Rum. We don't make a 125 gr bullet so I'm using data on our 150BD2 bullet from a 308Win with a 24" 1:9 barrel. 52 gr of LVR in SRP brass was used. A trajectory was calculated for both bullets, the 124 HH and the 150 BD2, at the same altitude and temp. Note the 125HH shot from the 300RUM at 3900 fps has a 725 fps MV advantage over the 150BD2, yet at 700 yds the 150BD2 is going slightly faster than the 124HH entirely due to the BC difference. Excellent example of how speed cannot substitute for BC. The lower BC bullet simply loses energy and speed faster to air friction than the high BC bullet.
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Y'all haven't covered it all yet?
very thorough you are!
very thorough you are!
I understand all of that but I'm way north of 3900fps and the BC doesn't concern me, I have verified my data at distance and the 124 is what I choose,
HARPERC
Well-Known Member
So if I read correctly the 168 CC has a reported BC of 0.462, and the ELDM of 0.523?
Yet it looks like from limited data, more BC did not pay off here?
Mr. xsn10s, You appear to strive for transparency and, more so, accuracy. I pray you are not offended by my request, that is; clean up your data. Please don't continue to mix MKS (meter, kilogram, second) with the Imperial you exhibit in your Output Data. An oversight here and there diminishes the veracity of your points of debate.
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nralifer
Well-Known Member
I was hoping would get around to lethality. We have approached our bullet design from a different persoective. I am a surgeon by training specializing in urology. During my first 2 years of residency I spent at least half at a level 1 trauma center, SF General Hospital, and got to see a wide variety of penetrating and blunt trauma. The most lethal wounds were either penetrating trauma to the vena cava or blunt trauma to the heart. The mechanism of death was always severe low blood pressure either because the bleeding could not be contained, as in the case of vena cava tears or pump failure from severe bruising of the heart muscle as in the case of blunt injury to the heart, hitting the steering column in an auto accident for example. In hunting big game, a catastrophic drop in blood pressure causes rapid unconsciousness because of lack of brain perfusion. An expanding bullet hitting the top of the heart will take out both the main pulmonary artery and aorta causing an immediate catastrophic hemorrhage with resultant immediate and profound drop in blood pressure with cessation of brain activity. The animal is dead right there. Shots through the mid to rear chest are fatal eventually but are not likely to lead to catastrophic blood loss. If both entrance and exit holes are small, what happens is that as the animal inhales, air leaks out into the space called the pleural cavity, causing a gradual buildup of air pressure around the injured lungs that collapses them under pressure causing all blood flow through the lungs to stop, C causing a drop in heart output and blood pressure to the point that the brain stops working and the animal collapses. If the exit hole is large then air pressure does not build up in the pleural space and prevents the complete collapse of the lungs without a rapid drop in blood pressure. The animal can run a considerable distance and die later from exhaustion, infection, or predation, Copper, being considerably harder than lead, will not deform unless the front of the bullet is weakened by a hole. Expansion of the bullet is poor unless there are groves cut into the wall of the hole which act as stressors and allow the copper to tear along those groves, causing the petals to be formed and rolled back. Since the bullet is also spinning about it's longitudinal axis at over 200,000 RPM, these petals act like propeller blades and assist the bullet in penetration. The high forward velocity of the expanded bullet causes a large temporary wound cavity behind the bullet. Non-expanding FMJ bullets just pencil through causing much less tissue damage and much smaller temporary wound cavities. Weight retention is high which adds to the momentum of the bullet, thus adding penetration. The expanded front end also contributes to a straighter path and prevents tumbling. Expansion is around 1.5 calibers. The high BC of our bullets extends the range before minimum expansion velocity is reached. At very high impact velocity, at least in gel, the petals can shear off usually within 10-12 inches snd subsequent tumbling of the shank. No expansion scheme can compensate for a poorly placed shot however.
Photos are of various bullets showing the type of expansion they have in 10% gel.
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