Bullet Construction vs Lethality

[asd9055]

Maybe you should look up "tracking point firearms" -- not radar, but it's been available since 2011.not really a pipe dream if you have enough money

Made in Austin Texas of all places

 

[Muddyboots]

Thank you for the question, This is an excellent question, and deserves a thoughtful answer. I'll try and give it a just answer.
Recall that a bullet shot from a rifled barrel has two main movements. The linear motion towards the target, and spin motion imparted to it by the rifling, giving it a gyroscopic stability that keeps it going nose first to the target. The spin required to do this properly is largely a function of the medium density the bullet travels in, the caliber and length as well as the weight of ghe bullet. Initially it is the air the bullet encounters and the denser the air the more spin needed. Also, the length and caliber of the bullet is very important, as well as the density of the material the bullet is made of. Short fat lead bullets, say .45 caliber require a 1:14 twist, under standard atmospheric conditions, to be stabilized (1atm pressure, 50% humidity , and 59 degrees F), but a 100 gr copper high BC bullet 6mm bullet with a long ogive requires a 1:7 twist to achieve adequate stability because it is a much longer and thinner bullet. The 6 mm bullet needs to be spun at about 300,000 rpm to stabilize in air at sea level atmospheric pressure. When the bullet enters flesh or gel, suddenly the density of the medium the bullet is traveling in, increases. A long thin bullet can become unstable unless it shortens by expansion or is marginally stable at impact. This mushrooming or petaling also enlarges the bullet diameter at the mushrooming, both of which have a stabilizing effect because the bullet is still spinning. A marginally stable bullet at impact will start to tumble and not expand as intended regardless of bullet material.

Not a question but a statement of why some bullets fail due to "insufficient stability" for best terminal performance of a bullet. It will prob shoot fine on target but not necessarily perform its best when entering a "medium" such as an animal. IMO shooters need to pay little more attention to getting higher SG to insure best terminal performance. Thanks for adding further explanation to my statement though.

I have changed how I select for a bullet with criteria number one is a SG of ~2.0 as a starting point. Terminal performance trumps everything. If bullet cannot deliver its best terminal performance aka lethality whats the point of using it? Not right, not wrong, just MHO.

 

[memtb]

We are able to discuss virtually anything here, including pipe dreams, or maybe it's a thought that was brought about by smoking some silly stuff in that pipe. I don't see this being an actual topic for discussion. If this was possible then the big manufacturers would have done it years ago. It falls into the category of radar guided bullets where all you have to do is point your firearm in the general direction of the target and it will guide itself to a perfect shot. Dream on.

Yep! Some of this conversation has developed into "virtual "!

I sincerely hope that hunting/shooting will never become another virtual reality living room sport! memtb

 

[memtb]

I just like shooting things like rocks and various jugs, cans etc. at 400 yards. Old eyes don't work good after that.

It must be nice to be @ble to shoot irons at any distanc! I used to love to shoot irons, and actually thought that I was pretty fair…..now, I could close my eyes and do as well! memtb

 

[memtb]

Maybe you should look up "tracking point firearms" -- not radar, but it's been available since 2011.not really a pipe dream if you have enough money

The Navy has been using them (or similar) since my brother was in the Navy in the mid-'70's……but, what in the hell does this have to do with sporting firearms and/or hunting!

Why don't we all get into virtual reality enjoy hunting/shooting from our living rooms……and give up our firearms to the government! memtb

 

[can1010]

you need to decide what type of bullet construction you are going to use before you decide on a SG#.
cup and core will stabilize and put round holes in paper at a 1.2 SG but a 1.2 with a mono bullet leaves a nice sideways bullet profile in the paper. an SG of 1.5 is a good stare with cup and core for hunting but not ideal for mono. 2.0+ SG being ideal for mono but that many rpms with long range bullets designed to expand at lower velocities will take a chance of ripping them apart.
so saying that 2.0+SG will be good for every situation won't work. there is more to consider than just a #

Not a question but a statement of why some bullets fail due to "insufficient stability" for best terminal performance of a bullet. It will prob shoot fine on target but not necessarily perform its best when entering a "medium" such as an animal. IMO shooters need to pay little more attention to getting higher SG to insure best terminal performance. Thanks for adding further explanation to my statement though.

I have changed how I select for a bullet with criteria number one is a SG of ~2.0 as a starting point. Terminal performance trumps everything. If bullet cannot deliver its best terminal performance aka lethality whats the point of using it? Not right, not wrong, just MHO.

 

[xsn10s]

It must be nice to be @ble to shoot irons at any distanc! I used to love to shoot irons, and actually thought that I was pretty fair…..now, I could close my eyes and do as well! memtb

My old eyes are getting tired too. I thought I'd have to switch completely to optics and red dots. Turned out I just can't see my stainless steel sights well anymore. I picked up a new edc this year and turns out I can see the sights good enough to hit moving targets out to 60 yards, stationary targets out to 200 yards. I'll need to practice in order to hit farther out like I used to. I'll have to get my FAL out to see if I can hit steel out to 750 yards with it anymore. I don't know if I can see the steel that far with irons anymore lol.

 

[memtb]

My old eyes are getting tired too. I thought I'd have to switch completely to optics and red dots. Turned out I just can't see my stainless steel sights well anymore. I picked up a new edc this year and turns out I can see the sights good enough to hit moving targets out to 60 yards, stationary targets out to 200 yards. I'll need to practice in order to hit farther out like I used to. I'll have to get my FAL out to see if I can hit steel out to 750 yards with it anymore. I don't know if I can see the steel that far with irons anymore lol.

Maybe I should try harder……paint sights, ect.!

I'm still good (enough) for handgun sights at typical handgun defense ranges…..usually measured in feet! memtb

 

[Petey308]

Not a question but a statement of why some bullets fail due to "insufficient stability" for best terminal performance of a bullet. It will prob shoot fine on target but not necessarily perform its best when entering a "medium" such as an animal. IMO shooters need to pay little more attention to getting higher SG to insure best terminal performance. Thanks for adding further explanation to my statement though.

I have changed how I select for a bullet with criteria number one is a SG of ~2.0 as a starting point. Terminal performance trumps everything. If bullet cannot deliver its best terminal performance aka lethality whats the point of using it? Not right, not wrong, just MHO.

Copper bullets have always required an SG of 2.0 to be fully stabile, get their full BC potential, and to be most accurate on target. That wasn't as well known as it's now starting to become though.

I'd say certain softer constructed lead core bullets would still perform more balanced, terminally, with only around an SG of 1.5 vs 2.0 though. And lead core bullets, being more dense and shorter grain for grain than a copper bullet, only require an SG of 1.5 to be fully stabile, get their full BC potential, and to be most accurate on target. Most know this, so I'm just reiterating.

I'd also love to see how fast a bullet arrests it rate of spin upon impact, and how different densities affect it more or less. And from that, of the different types of bullet construction and material, as well as the mechanisms for how it expands and behaves terminally, affects how much or how little it slows or stops it's rotation.

I have my theories, but I'd love to turn that into as much fact as possible, whether that proves or disproves my theories.

Either way, if you're hunting with any copper mono, you're only doing yourself and the animal a disservice by not getting it to at least an SG of 2.0 and that would go for even just target shooting with them.

 

[3chester]

Maybe I should try harder……paint sights, ect.!

I'm still good (enough) for handgun sights at typical handgun defense ranges…..usually measured in feet! memtb

ThinkN that's why S&W made the Governor, for the older customers. So's in between each 45 Colt round, a Guy can put a 410 gauge shell with 1/2 ounce #8 shot. That way ,whatever ur shootN, at least knows you're serious.

 

[nralifer]

Not a question but a statement of why some bullets fail due to "insufficient stability" for best terminal performance of a bullet. It will prob shoot fine on target but not necessarily perform its best when entering a "medium" such as an animal. IMO shooters need to pay little more attention to getting higher SG to insure best terminal performance. Thanks for adding further explanation to my statement though.

I have changed how I select for a bullet with criteria number one is a SG of ~2.0 as a starting point. Terminal performance trumps everything. If bullet cannot deliver its best terminal performance aka lethality whats the point of using it? Not right, not wrong, just MHO.

No worries. Enjoyed expounding on your statement. Could you name a specific instance where you had this problem, not necessarily the brand name but the bullet type and length and caliber and what you think happened if you can recall these details?

 

[Noobie]

Just a side note: The original 5.56 round fired in a 1:14 twist M-16 BBL was deliberately designed to tumble upon hitting soft tissue to cause severe damage despite using non-expanding FMJ bullets mandated by conventions and treaties.

 

[nralifer]

Copper bullets have always required an SG of 2.0 to be fully stabile, get their full BC potential, and to be most accurate on target. That wasn't as well known as it's now starting to become though.

I'd say certain softer constructed lead core bullets would still perform more balanced, terminally, with only around an SG of 1.5 vs 2.0 though. And lead core bullets, being more dense and shorter grain for grain than a copper bullet, only require an SG of 1.5 to be fully stabile, get their full BC potential, and to be most accurate on target. Most know this, so I'm just reiterating.

I'd also love to see how fast a bullet arrests it rate of spin upon impact, and how different densities affect it more or less. And from that, of the different types of bullet construction and material, as well as the mechanisms for how it expands and behaves terminally, affects how much or how little it slows or stops it's rotation.

I have my theories, but I'd love to turn that into as much fact as possible, whether that proves or disproves my theories.

Either way, if you're hunting with any copper mono, you're only doing yourself and the animal a disservice by not getting it to at least an SG of 2.0 and that would go for even just target shooting with them.

Good question about when the spin of the bullet stops. Theoretically it can differ by the mass of the bullet. A heavy for caliber bullet shot from a given twist barrel will have more angular momentum than a lighter bullet shot from the same barrel at the same speed, so it will maintain it's rotation longer through an animal. In our gel testing we see evidence in the bullet track through the clear gel that is spirals to at least a16 inches and the heavier 338 bullets can go as far 25-32+ inches.

In so far as the blanket statement that copper bullets require tighter twists, that is true to some extent due to the fact that copper is less dense than lead (8.89g/cc vs about 10.5 g/cc). So to make a copper bullet of the same weight it has to be longer. However, in a 30 cal 1:10 twist will accommodate our 150-195 gr bullets very well, but when you get to a 205 gr bullet, a 1:8 twist is needed, so there is some overlap. That said, "over stabilizing" a copper bullet never hurts and may add to it's lethality because of the faster rotational velocity. The reverse is not always true. I have seen this problem with A-Tips blowing up in mid flight when shot out of a 1:7.5" twist barrel. Actually, I bought that barrel from him and it shot our bullets down to 1/4 moa with little load development.

To compensate use a lighter for caliber bullet. This is not a real handicap. For hunting purposes petaling copper bullets will outpenetrate lead cores even the light for caliber coppers. I have seen that over and over with Barnes and ours. In our first hunt with the first generation Bulldozers shooting 7 Plains Game animals, including a Bush Pig longitudinally through the head we recovered 0 bullets. All pass throughs. We were using a 308 Win and an MV of 2920 fps and made shots out to 500 yds.

 

[Calvin45]

The Hammer cult and the owners of hammer told Brian Litz he didn't know what he was talking about when he exposed Hammers inflated BC's.

Really?