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Comparing the Berger 210 VLD to the 215 Hybrid

 
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  #120  
Old 10-26-2012, 07:19 AM
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re: Comparing the Berger 210 VLD to the 215 Hybrid

Good thread indeed.

Thank you Broz for posting your thorough results.

On the issue of RPM vs. terminal performance, I don't know of any tests done specifically in this area, so I can't cite any facts. However, we can consider the energy balance to gain some insight.

Example:
A .30 cal 175 grain bullet moving at 2800 fps has 3046 ft-lb of translational (linear) kinetic energy (KE). When fired from a 1:12" twist barrel, that bullet also has about 9 ft-lb of rotational kinetic energy.
[REF Applied Ballistics for Long Range Shooting, pg 108]

So far, what this analysis shows me is that the majority (99.7%) of the bullet's total kinetic energy is translational. To me, this suggests that most of the damage done by a bullet is due to it's translational energy, not it's rotational energy.

Continuing with the example, if the same .30 cal 175 grain bullet were now fired at the same MV from a 1:10" twist barrel, the translational energy would stay the same, but the rotational kinetic energy would increase to 10.8 ft-lb. So although the rotational KE did increase by 20%, the fraction of total energy only increased from 0.296% to 0.355%.

So the energy analysis seems to suggest that you would see no difference in terminal performance due to a difference in twist rate.

But is that all there is to it?

For example, is it possible that riflings engraved on a bearing surface at a greater angle (by a faster rifling twist) might weaken the bullet more and promote more rapid expansion? I don't know.

-Bryan
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  #121  
Old 10-26-2012, 07:49 AM
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re: Comparing the Berger 210 VLD to the 215 Hybrid

So with a given bullet velocity gives you an amount of translational energy, and bullet construction determines the rate at which that energy is transferred into a medium.

follows what I've seen from from game rifles to varmint rifles, lightly constructed bullets want to dump it's energy quick while more sturdily constructed bullets want to hang onto their energy more.
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Keep in mind the animals we shoot for food and display are not bullet proof. Contrary to popular belief, they bleed and die just like they did a hundred years ago. Being competent with a given rifle is far more important than impressive ballistics and poor shootability. High velocity misses never put a steak in the freezer.

Joe
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  #122  
Old 10-26-2012, 08:45 AM
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re: Comparing the Berger 210 VLD to the 215 Hybrid

Quote:
Originally Posted by bsl135 View Post
Good thread indeed.

Thank you Broz for posting your thorough results.

On the issue of RPM vs. terminal performance, I don't know of any tests done specifically in this area, so I can't cite any facts. However, we can consider the energy balance to gain some insight.

Example:
A .30 cal 175 grain bullet moving at 2800 fps has 3046 ft-lb of translational (linear) kinetic energy (KE). When fired from a 1:12" twist barrel, that bullet also has about 9 ft-lb of rotational kinetic energy.
[REF Applied Ballistics for Long Range Shooting, pg 108]

So far, what this analysis shows me is that the majority (99.7%) of the bullet's total kinetic energy is translational. To me, this suggests that most of the damage done by a bullet is due to it's translational energy, not it's rotational energy.

Continuing with the example, if the same .30 cal 175 grain bullet were now fired at the same MV from a 1:10" twist barrel, the translational energy would stay the same, but the rotational kinetic energy would increase to 10.8 ft-lb. So although the rotational KE did increase by 20%, the fraction of total energy only increased from 0.296% to 0.355%.

So the energy analysis seems to suggest that you would see no difference in terminal performance due to a difference in twist rate.

But is that all there is to it?

For example, is it possible that riflings engraved on a bearing surface at a greater angle (by a faster rifling twist) might weaken the bullet more and promote more rapid expansion? I don't know.

-Bryan
So this topic as it relates to Rich's question is does the increase in rotational energy, whether created by an increase in barrel twist rate or an increase in initial muzzle velocity, cause enough additional energy to change the expansion characteristics of a bullet.

I tend to agree that the RPMs don't have much effect on terminal performance by themselves but I do have a feeling they could change how rapidly or explosively the expansion may occur, thus drastically changing terminal performance. My thoughts are based solely on very anecdotal evidences but on occasion I have seen big differences when shooting prairie dogs and chucks with the same setup in 2 guns except one has a faster twist. The faster twist barrel often seems to cause more explosive outcomes. I imagine many other factors come into play here including impact velocity, jacket thickness and target medium density, where with some loads there isn't enough of an increase to make a difference while with others, that may be teetering on the threshold, they may be pushed over the edge by the increase in rotational energy and more expansion occurs.

This is a fantastic thread. Just re-read the whole thing again because it is so good! Thanks Jeff, Eric, and Bryan for sharing such valuable info!

Scot E.
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  #123  
Old 10-26-2012, 09:01 AM
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re: Comparing the Berger 210 VLD to the 215 Hybrid

Quote:
Originally Posted by Scot E View Post
So this topic as it relates to Rich's question is does the increase in rotational energy, whether created by an increase in barrel twist rate or an increase in initial muzzle velocity, cause enough additional energy to change the expansion characteristics of a bullet.

I tend to agree that the RPMs don't have much effect on terminal performance by themselves but I do have a feeling they could change how rapidly or explosively the expansion may occur, thus drastically changing terminal performance. My thoughts are based solely on very anecdotal evidences but on occasion I have seen big differences when shooting prairie dogs and chucks with the same setup in 2 guns except one has a faster twist. The faster twist barrel often seems to cause more explosive outcomes. I imagine many other factors come into play here including impact velocity, jacket thickness and target medium density, where with some loads there isn't enough of an increase to make a difference while with others, that may be teetering on the threshold, they may be pushed over the edge by the increase in rotational energy and more expansion occurs.

This is a fantastic thread. Just re-read the whole thing again because it is so good! Thanks Jeff, Eric, and Bryan for sharing such valuable info!

Scot E.
I can say much about the rotational velocity of a varmint bullet as I have only one 22cal varmint rifle, but I can tell you the difference between 2 bullets of the same weight and manufacture, can produce dramatically different results, even with as slow of a twist as can be used for those particular bullets. Specifically the Hornady 55gr w/canular, produces ho hum terminal results, where the 55gr Vmax is........well pieces parts go flying.
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Keep in mind the animals we shoot for food and display are not bullet proof. Contrary to popular belief, they bleed and die just like they did a hundred years ago. Being competent with a given rifle is far more important than impressive ballistics and poor shootability. High velocity misses never put a steak in the freezer.

Joe
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  #124  
Old 10-26-2012, 11:07 AM
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Join Date: Dec 2008
Location: Northern Id.
Posts: 3,312
re: Comparing the Berger 210 VLD to the 215 Hybrid

Quote:
Originally Posted by Scot E View Post
So this topic as it relates to Rich's question is does the increase in rotational energy, whether created by an increase in barrel twist rate or an increase in initial muzzle velocity, cause enough additional energy to change the expansion characteristics of a bullet.

I tend to agree that the RPMs don't have much effect on terminal performance by themselves but I do have a feeling they could change how rapidly or explosively the expansion may occur, thus drastically changing terminal performance. My thoughts are based solely on very anecdotal evidences but on occasion I have seen big differences when shooting prairie dogs and chucks with the same setup in 2 guns except one has a faster twist. The faster twist barrel often seems to cause more explosive outcomes. I imagine many other factors come into play here including impact velocity, jacket thickness and target medium density, where with some loads there isn't enough of an increase to make a difference while with others, that may be teetering on the threshold, they may be pushed over the edge by the increase in rotational energy and more expansion occurs.

This is a fantastic thread. Just re-read the whole thing again because it is so good! Thanks Jeff, Eric, and Bryan for sharing such valuable info!

Scot E.
I can see where the amount of energy released is very slight compared to total energy, but I'm with you on the effect on expansion. I read an article YEARS ago which I believe was conducted by the military dealing with this. In the test, they used an M1 carbine with a 16" twist and an M1 rifle with a 10 twist both firing a 110 grain bullet. The carbine, I believe. is around 2000' per second and was fired point blank into gel. The '06 was fired at a distance to achieve the same terminal velocity upon impact. The results were amazing with the pics of the wound cavity clearly being FAR larger in favor of the '06. Given Bryans info on the amount of energy difference being fairly insignificant, it only bolsters my belief that EXPANSION must be greater. I suspect that both expansion and energy play some role, but how much? Unforunately, this test didn't recover the bullets but this would not be a difficult test to perform.........Rich
I think we are in danger here of hijacking Jeffs thread so I am going to start a new one "rotational velocity vs wound severity".

Last edited by elkaholic; 10-26-2012 at 12:39 PM.
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  #125  
Old 10-26-2012, 11:28 PM
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re: Comparing the Berger 210 VLD to the 215 Hybrid

Yet more data on the terminal performance of the 215 Berger Hybrid in "live test media that tastes yummy".

Ok, but this one comes with a story, as it was a cool hunt. I have a good friend that is 72 years young. I have been with him on many of his elk kills and I know he can make a steady shot and brake a clean trigger. So today I was glassing an area and found an unusual bull elk in a small grove of trees. Problem is, you can't get to elk in this area. If you come over the back to go down on them they will bust you and be gone. It is steep and coming from the bottom would be a waste of breath, they will see you, I know from experience. So the only way is from the other side of the canyon across a deep gulch. I left and went and picked up my friend in hopes the bull would stay put in the trees. We returned and got set up in a good vantage point as close as we could on the other side. After about 1/2 hr of glassing and just about ready to give up, the Bull appeared. I set my PLRF10 on bags prone and ranged him. The instant I seen the range I knew this bull was in trouble. The range.... 777 yds. My Applied Ballistics App spit out 13.75 MOA up and .5 MOA right for SD and a 3 mph 3:00 wind. I dialed it and got my friend behind my 300 Win for his longest poke ever. It took a few minutes for him to get solid as I coached him through the shot. The bull took two steps toward the timber and I let out a cow call and stopped him. As he stopped broadside and staired over at us laying prone my friend broke the shot. I watched and upon arrival of the 215 Berger, the bull crumpled like he was struck by lightning and rolled into some trees. I told him to chamber another round and get ready incase the bull surface again. A few minutes later we knew the bull was down and done DRT. So we started over to see the results. Now here is where it gets cool.

The bull was at 777 yards.
My friend is 72 yrs old.
The bull has a deformed horn on one side that looks like a 7.

Thats a lot of sevens guys!! So when we got home we set down and had 7&7 and talked about the great hunt and my friends longest shot of all his hunting years. I think this story will get told a lot.

Now for the pics and facts:

Impact velocity = 2207 (another 7)
mpact energy = 2325
Bullet placement was a little high and a little back but not bad. ( no worries, the fragmenting Berger covered for us)
Outside entrance was .308" like all the others
Complete pass through with an exit of 1" to 1 1/4" exit hole taking a rib on the way out.
Severe bleeding both internal and external with destroyed lungs and damaged heart.

The pics:

The exit:




Exit from inside chest cavity:



Tore up vitals:




The seven Bull:




The hero pic with the shooter of the day:




My thoughts tonight. My confidence increasingly grows for this bullet as my hunting bullet. How could it not? My earlier predictions of the bullet working better, with increased chances of a pass through, at longer distances, seems to be on track. We now have had complete pass throughs on game at 777 yds, 802 yds, 1005 yds, and 1285 yards. All exits showing good expansion.

Look at the results for yourself, it is all here. There is more hunting to do. Going after a good Muley Buck tomorrow. More results to come. Thanks for reading.

Jeff
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  #126  
Old 10-27-2012, 01:41 AM
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re: Comparing the Berger 210 VLD to the 215 Hybrid

Thank you Jeff for doing such a thorough job on your reporting of details. I have enjoyed the reports thus far. I was already pretty comfortable going into this year's hunts using the 215 but you have really boosted my confidence in the performance of this bullet.
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