urbanrifleman
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Here is the 53 vmax at 3650 compared to the 75 ELDM at 3350. They match velocity at 200 yards.
Bullets and BC to Hit Hard (Maybe we need to rethink)
- Thread starter urbanrifleman
- Start date
Here is the 53 vmax at 3650 compared to the 75 ELDM at 3350. They match velocity at 200 yards.
jelenko
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A bullet going 3200 fps in an 8 twist has 288,000 RPM's. From Hornady, at least for their 75hpbt's, they strongly recommend RPM's below 280,000.
urbanrifleman
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Yeah there has been a real problem with trying to establish what twist is best for these bullets since the recommended twists exceed the RPMs that they don't recommend. Which seems kind of silly. I will say that I shot the 75 at a significantly higher speed than that and they did not blow up out of my 26 inch barrel
urbanrifleman
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AckleymanII
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80g EldM in 22/243 AI, CIP reamer for Lapua is real world bad dog, the 80's take the RPM! 3550 is real world 26", 3650 is really working on the primer pockets in lapua brass.
80g ELD-M are deer and hog killers, extraordinaire!
80g ELD-M are deer and hog killers, extraordinaire!
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Explosion has more to do with bullet design than weight or velocity in my experience. An 80 gr. match bullet 3300fps at 300 yds isn't going to explode a Prarie dog as much as a 50g Varmint bullet at 3800 fps. From what I've seen.
urbanrifleman
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The ELDM is the same jacket as a vmax and same poly tip.
Those 22 cal Barnes 36 gr Varmint grenades might have more drop at 500 yards, but I’ve never seen another bullet that will make pdogs vaporize as they will. A few more clicks on the scope keeps them on target just fine really.
So here's another good point lightly brought up. I've read it smattered across this forum as well that all else being equal, higher RPMs would make more splody too. Some statements to the effect of higher RPMs may be on par with velocity...
Obviously there's an upper limit, as soon bullets too fast and they splody before they get there. I'd love to see a back to back test, to see if this bullet spin speed difference makes an effect.
From the charts above, yes BC carries more energy downrange, however is the impact energy only what makes splody, or does the kinetic spin energy contribute significantly too?
-Mac
I agree, I use 40 grain VMAX in my 223 and 75 grain VMAX in my 6MM Remington. Within their REAL functional range these are explosive. If you catch a chuck in the head just right it removes most of the skull. Body shots produce massive exit wounds.
What's real functional range? I'v been shooting the farm fields around here since 1965 and the now terraced fields and changes in wooded area have changed the shooting tremendously. Across 600 yards the wind can change direction a few times and eddy currents are worse than urban conditions due to the extended ranges. The population dispersal is such that shooting multiple shots to make a hit at ranges exceeding these dictates the use of tru fragile varmint bullets less one bounces and hits an unintended target.
In a 22" bolt rifle in 223 if the wind in not gusting I can pick head shots at 350 yards. In a 26" 6MM Remington the wind can be significantly more forceful and I can pick head shot at 450 yards. Both rifles run 3,900 FPS, the 223 has a 1 in 12 and the 6MM 1 in 9 twist.
Recently I missed a body shot on a chuck at 425 yards with my 223, it caught the head and produced an exit wound larger than a golf ball.
A few years back a similar situation at 600 yards with my 6MM the head was devastated.
In my area using high BC projectiles for varmints is a poor choice IMO.
urbanrifleman
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I do not understand this statement. The ELDM is essentially a high BC poly tip varmint bullet.
I may have a partial explanation for this phenomena:
For reference
rotational kinetic energy is:
E=1/2(moment of inertia)x(angular velocity)^2
Linear KE is:
E=1/2(mass of bullet)x(velocity)^2
It has to do with shrapnel cones and energy transfer.
An example to show what I'm saying. Think about throwing a tennis ball out of a moving car and the angle the balls path has relative to the car. If you throw the tennis ball at the same speed perpendicular to the car every time, the angle of the tennis ball's path has will be shallower compared to the direction of travel the faster the car goes. Its velocity in the direction of the car travel will be higher than the velocity you throw it out at. The faster the car goes the shallower the angle, the slower the car goes the higher the angle (with the car stopped having the ball thrown out at the full 90 degrees perpendicular). The tennis ball is a bullet fragment coming off of a bullet when it hits the target.
We know linear velocity decays faster than rotational velocity (stability factor of bullets goes up as they travel). So rotational kinetic energy is more easily stored than linear during bullet travel.
Angular velocity increases with twist rate of the barrel and bullet velocity. Moment of inertia increases with bullet mass. Angular velocity is the squared term so (proportionally) increasing twist rate and velocity will have more an effect on rotational energy that bullet mass does (though heavier bullets need more twist).
Now apply this to bullet fragments. Lets talk about the same bullet hitting at different ranges. The faster the bullet is going when it hits the target is analogous to the car moving faster. The Shrapnel cone inside the target will be narrower and some energy is wasted blowing out the back. The slower the bullet is going when it hits the target the slower the car is moving the wider the shrapnel cone is. The faster the bullet is spinning equates to throwing the ball faster which also widens the cone.
But the bullet needs to violently fragment for this to occur. And it is impacting a target with enough linear velocity that causes this. Doesn't matter how fast its spinning (before it literally spins itself apart) it won't do much damage if it hits at women's slow pitch softball speeds. This is why as the size of the animal goes up the weight of the bullet suggested goes up as well. Deeper wounding with a higher ratio of linear to rotational energy.
So In summery I think its like this:
With the right mix of linear and rotational velocity at impact the maximum amount of energy transfer occurs to the widest possible area inside the target and the target explodes like it swallowed an m80.
With the same bullet higher RPM at the same impact speed will do more damage.
Too much linear velocity (compared to rotational) the shrapnel cone is smaller inside the target and it blows a smaller hole through it.
Not enough linear velocity at impact and the bullet doesn't fragment completely and you get a reduced effect on the target.
Keep in mind the faster you shoot a bullet through the same twist rate barrel the faster it spins as well.
For additional reference.
An Official Journal Of The NRA | Barrel Twist Rates: Can They Impact Bullet Expansion?
Do barrel twist rates do more than just make a bullet accurate? The experience of two Remington engineers shows that they can do much more than that.
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It's not a varmint bullet it's a match bullet. Essentially is not exactly, I shoot match bullets and varmint bullets and varmint bullets destruct much easier at lower velocities.
The reality is this at long ranges in the field misses are far more prominent than hits. We only hear about that 1,000 yard hit, not the 10 misses. In my area we have had at least 2 women hit by varmint hunters, both times inappropriate projectiles and IMO inappropriate caliber.
urbanrifleman
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urbanrifleman
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Most match bullets have much thicker jackets than varmint bullets.
Let's not confuse one with the other. The ELDM has a varmint jacket, as did the A Max before it.
Great! Thank you!I may have a partial explanation for this phenomena:
For reference
rotational kinetic energy is:
E=1/2(moment of inertia)x(angular velocity)^2
Linear KE is:
E=1/2(mass of bullet)x(velocity)^2
It has to do with shrapnel cones and energy transfer.
An example to show what I'm saying. Think about throwing a tennis ball out of a moving car and the angle the balls path has relative to the car. If you throw the tennis ball at the same speed perpendicular to the car every time, the angle of the tennis ball's path has will be shallower compared to the direction of travel the faster the car goes. Its velocity in the direction of the car travel will be higher than the velocity you throw it out at. The faster the car goes the shallower the angle, the slower the car goes the higher the angle (with the car stopped having the ball thrown out at the full 90 degrees perpendicular). The tennis ball is a bullet fragment coming off of a bullet when it hits the target.
We know linear velocity decays faster than rotational velocity (stability factor of bullets goes up as they travel). So rotational kinetic energy is more easily stored than linear during bullet travel.
Angular velocity increases with twist rate of the barrel and bullet velocity. Moment of inertia increases with bullet mass. Angular velocity is the squared term so (proportionally) increasing twist rate and velocity will have more an effect on rotational energy that bullet mass does (though heavier bullets need more twist).
Now apply this to bullet fragments. Lets talk about the same bullet hitting at different ranges. The faster the bullet is going when it hits the target is analogous to the car moving faster. The Shrapnel cone inside the target will be narrower and some energy is wasted blowing out the back. The slower the bullet is going when it hits the target the slower the car is moving the wider the shrapnel cone is.
But the bullet needs to violently fragment for this to occur. And it is impacting a target with enough linear velocity that causes this. Doesn't matter how fast its spinning (before it literally spins itself apart) it won't do much damage if it hits at women's slow pitch softball speeds. This is why as the size of the animal goes up the weight of the bullet suggested goes up as well. Deeper wounding with a higher ratio of linear to rotational energy.
So In summery I think its like this:
With the right mix of linear and rotational velocity at impact the maximum amount of energy transfer occurs to the widest possible area inside the target and the target explodes like it swallowed an m80.
Higher RPM at the same impact speed will probably do more damage.
Too much linear velocity (compared to rotational) the shrapnel cone is smaller inside the target and it blows a smaller hole through it.
Not enough linear velocity at impact and the bullet doesn't fragment completely and you get a reduced effect on the target.
Keep in mind the faster you shoot a bullet through the same twist rate barrel the faster it spins as well.
For additional reference.
An Official Journal Of The NRA | Barrel Twist Rates: Can They Impact Bullet Expansion?
Do barrel twist rates do more than just make a bullet accurate? The experience of two Remington engineers shows that they can do much more than that.www.shootingillustrated.com
-Mac
B23
Gold $$ Contributor
And to add to that, from what I've been told by Berger their "Hunting" bullets have thinner jackets than does their target bullets.
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