What is your hypothesis on why your tests depict accurate expansion for all the bullets except Berger?
bullet expansion test results
- Thread starter yorke-1
- Start date
Help Support Long Range Hunting Forum
What is your hypothesis on why your tests depict accurate expansion for all the bullets except Berger?
I believe it's the hollow point cavity and the thickness of the jacket on some of them like the Elites. Almost all the other bullets have a lead corr all the way to the tip or actually have a plastic tip like the Hornady and Nosler bullets. The HP bullets need a hydraulic force to help them open otherwise the tip gets pluged up and essentially turns the bullet into a solid.
The medium I'm using is a good replacement for the hide on an animal but it doesn't do a good job of replicating what happens when a bullet gets into the chest cavity. Likewise, I don't think shooting them into straight water is a good representation either because water doesn't stretch or give on impact like tissue does.
Some of the results I've had explain why sometimes you see reports of bullets penciling through and not expanding. If the HP gets damaged or plugged up with hair or hide it can't get forced open by fluids in the chest cavity. That's probably why guys see better results after opening up the tips on some of the HP bullets. I see this a lot when I've tested handgun bullets over the years. The HP gets plugged with material and it just acts like a FMJ when it hits the target.
Andrew
bigngreen
Well-Known Member
Bullets react differently with spin rate also, down loaded rounds don't have the centrifical force due to rotating speed that a full power load at a range that put the impact velocities the same.
Could you shine a little more light on this please?
Does Rotational force (RPM) not degrade in direct proportion to velocity, provided the initial twist rate is the same?
elkaholic
Well-Known Member
Rotational velocity degrades at a MUCH slower rate and I have run tests at distance with high mv vs point blank with low mv to duplicate the long range velocity. The difference in expansion is VERY noticeable with higher RV!......Rich
elkaholic
Well-Known Member
Water will normally open a HP bullet faster than most media. I think if you had water AHEAD of the wet leather, it would have a greater affect in expnding the Bergers, or the like. No "Scuba Diving Elk jokes Please".........Rich
I agree. I even got different results when testing the same bullets at similar muzzle velocities but from different styles of rifling. For the bullets that I have on hand and use on a regular basis, I'll get actual data at range. It's hard to get from 100-1000 yards in 5 shots or less to get good LR data. I've done it, but it was pure luck!
I think you're probably right, and I'm thinking about using small water balloons as aiming points for that reason. If I can't make a scuba diving elk joke though, can I say that I only shoot animals standing on the other side of a water fall?
Rich,
No doubt that the rotational force exerted on the bullet has a substantial influence on the terminal performance of the bullet. I've noticed similar results as well. I tested several hundred 230g Berger OTM into media at various velocities from 3,000fps down to 900 fps in 10 twist rifles. I found that the bullets that started at higher velocity and decelerated behaved in terminal results substantially better than bullets I loaded at low velocity and captured. I would love to pick your brain a bit more on this as well some sometime. I postulate that it is an artifact of the stress of the acceleration over the short distance of the barrel and deceleration to the target. If the bullet never goes through the acceleration and deceleration it is not stressed in a similar fashion as a bullet that starts at 3,000 fps and decelerates to impact velocity. Once outside the barrel Velocity decays in a supersonic body primarily from atmospheric density, followed by skin friction drag (smoothness of the surface), form drag (aerodynamic factors of the body) and the effect of gravity. However rotation of the bullet is directly proportional to it's forward velocity
Loving this thread. Would it be OK with the original poster if I uploaded some of the data I logged testing 230g Berger OTM bullets? I promise not to hijack this valuable thread any further.
elkaholic
Well-Known Member
Or just start a new thread! I never really considered the stress occurring before impact but we all know that centrifugal force is real and when a bullet starts to disrupt, it could not help but be exaggerated by much higher rpm!.....Rich
I never really considered the stress occurring before impact but we all know that centrifugal force is real and when a bullet starts to disrupt, it could not help but be exaggerated by much higher rpm!.....Rich
Predator 22
Well-Known Member
Wouldn't a bullet move most if not all the hair out of the way the same way it does rain? (sorry I can't remember for the life of me the technical term) like when you shoot a coyote and see the puff of hair when the bullet hits. I could see the hp getting plugged on a pistol more so than a rifle.
Broz
Well-Known Member
Ruptured pigs don,t bring much at sale. Just saying. Bacon anyone
Jeff
Jeff
bigngreen
Well-Known Member
It's fun to try
After doing a lot of testing I mellowed out a lot about terminal performance because it's honestly amazing what all goes into terminal performance and it's really awesome just how good of function we do see over all out of all classes of bullets. Throat wear and fouling can make a difference in cup an core bullets, I've seen bullets exploding mid flight to excellent penetration just because of fouling from shooting two jacket types that did not like each other. I find it fascinating, if it was not for the fact that I need less things to consume my time and money I'd be all over making my own bullets, it's absolutely fascinating!!!
Over 1.5 stability.
Tangent ogive bullets will open reliably if they stay above the 1.5 mark from what I have seen as long as the metplat is not closed (in game performance) and above 2000fps impact velocity. The same can be said using a secant ogive, but using a secant ogive, with the same metplat as a tangent ogive projectile: the enitial expansion; it is more abrubt, and expends most of its energy in the way of expansion in a much shorter amount of mass regardless of jacket thickness and anatomy.
Tangent ogive bullets will open reliably if they stay above the 1.5 mark from what I have seen as long as the metplat is not closed (in game performance) and above 2000fps impact velocity. The same can be said using a secant ogive, but using a secant ogive, with the same metplat as a tangent ogive projectile: the enitial expansion; it is more abrubt, and expends most of its energy in the way of expansion in a much shorter amount of mass regardless of jacket thickness and anatomy.
