Terminal Performance

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Terminal Performance

Post by stokesrj » Sat Jan 12, 2019 2:26 pm

The short barrel 308 project has stemmed some further research on the possible terminal effects of the various bullets this rifle shoots well. Of primary concern is the low impact velocity at range so I've been focusing on highly frangible bullets that will have a higher likelihood of quicker kills when ranges are long and velocities are low. To achieve this result the bullet must be designed with a thin jacket and wide meplat and of course this brings into question the close range, higher impact velocity performance of such a fragile (soft) bullet.

All bullets have a lower impact velocity threshold below which the bullet behaves as a solid with excessive penetration and a narrow wound channel. All bullets also have an upper impact velocity threshold above which the mass of the bullet is shed so quickly that penetration is compromised, creating a wide shallow wound that may fail to reach the vital organs.

The first bullet up for study is the Hornady # 30506 ELD Match bullet. My rifle likes this bullet and the Hornady Superformance Match factory load. This is my fall back loading in case I am unable to handload. It typically shoots 1/2 to 5/8 MOA from my 16.5" suppressed R8 barrel. And produces a muzzle velocity of approximately 2650 FPS which is very good for a short barrel. It took me several months to find a handload that would match and then surpass this level of performance so it is in my opinion a very good factory load.

The # 30506 ELD Match bullet is a simple cup and core, secant ogive, boat tail design with a polymer tip .308' diameter and weighing 168 grains. The gilded copper jacket is non tapered and is .020" thick. The polymer tip is 0.100" wide where it meets the jacket and the jacket opening forms a 0.090" hollow point which is filled with the stem of the polymer tip and promotes rapid fragmentation and expansion. The bullet is 1.270" log and 0.650" from base to ogive. Hornady lists the BC as .523 G1 and .263 G7 but this is true at high velocities only. If you dig into their more detailed data you will find that those ballistic coefficients were measured by doppler radar at mach 2.5 which is approximately 2,800 fps. When the velocity falls to mach 2 then the BC also falls to .516 G1 and .259 G7 and then at mach 1.75 it is .498 G1 and .251 G9.

The sectional density of a 168 grain .308 bullet made of a lead core and gilded copper jacket is .253. I believe this is important in that the 168 grain weight provides enough mass to insure adequate penetration for deer to elk sized game even with this high fragmentation designed bullet.

For the purposes of this test I have chosen to use bare 10% ballistic gel calibrated to the FBI standard. I realize it does not perfectly match the complex construction of a living animal with hide, muscle and sinew. However I have done enough tests with this medium and compared the results to live game that I think it is a relatively close match. Meaning that bullets I have recovered from game penetrated similar depths and look much the same as bullets recovered from the gel.

So here is a pic of the cross section of this bullet that I cut in half and photographed to give you a visual image of the construction of this bullet to match the dimensions listed above.
OTxQOncGQLuzhkZimTcO7A.jpg
After cross sectioning the bullet I also loaded some reduced loads to simulate mid, 300-400 yards, long range, 600-700 yards and then lower velocities to find a velocity that the bullets failed to expand. I chose to use H4895 powder for this purpose because it is a proven reduced load powder. Trailboss is also good for reduced loads but even the max loading of 15 grains produced no expansion and was difficult to capture a bullet. Penetration was in excess of 48".

First up is the testing at close range the most severe test for this bullet with an impact velocity from this rifle of 2625 fps.
High fragmentation, and 18" of penetration resulted in a very wide violent wound channel that would be devastating to any deer or elk on a broad side rib cage shot. Surprisingly the jacket and core did not separate and weighed 100.7 grains for 60% retained weight retention.
OTxQOncGQLuzhkZimTcO7A.jpg
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Re: Terminal Performance

Post by longrider » Sat Jan 12, 2019 4:28 pm

Thanks for the info, good job.

I have killed dozens of deer and antelope from 5-600 yards with a 16” suppressed.308 175gr SMK’s (factory FGMM @ 2500 fps Krieger 1:8); 12-15 deer, antelope, elk 8-571 yards with a 21” suppressed 300 win Blaser barrel 190 SMK @ 2805 fps; 15-20 of the same critters (2650-2700 fps running suppressed 20” Krieger/AINA 1:9.3”) 250 gr smk’s and scenars 18-709 yards. This last season I used my Blaser with the factory fluted match 25” running 300 Norma 230 berger otm @ 2825 fps (Ultra 7 I think you are familiar with) 70-500 yards - 2 antelope, 2 deer and one elk (pinhole entries, golf balls or better upon the exit)

The 300/338/300N have accounted for 28 Elk in the last 10 seasons.

Never lost one animal and only two made more than one step. One was a WT buck @ 8 yards with the 21” 300 win that ran 10-12 yards when I purposefully took only one lung trying to save the meat and a muley buck at 300 or so that I probably should have waited on, I jumped it and hit it a little too far back quartering heavily away on a trot with the .308, hitting the liver and only one lung. He went about 30 yards and piled up.

As you know, these are hard bullets driven at moderate velocity at best. I let the animal’s size, distance and angle determine where I place the shot. Sometimes I take a high shoulder shot to scatter secondary projectiles, neck -but normally double lung and/or heart shot.

These methods have worked very well for me.

This bull 1 shot in his bed @ 571yds 300 win 21” 190 smk, top right lung, plumbing from the top of the heart, lower left lung and lodged offside elbow. He never got up, just gave me head drop and back roll.

Recovered bullet shown.

WT doe 70 yards 2/3 quarter facing me DRT. One lung with the 230 otm 300N. No bullet recovery obviously.


059479E9-207E-468A-B2E8-86E32416DC3C.jpeg
26A865F9-2CF9-40B2-A0C6-84574802A6DF.jpeg
A3D8A47E-28A7-4BEE-B670-5EA4901A78AE.jpeg
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Re: Terminal Performance

Post by Rod » Sat Jan 12, 2019 4:40 pm

Hey Longrider, that's a nice Bull !

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Re: Terminal Performance

Post by longrider » Sat Jan 12, 2019 7:42 pm

Rod wrote:
Sat Jan 12, 2019 4:40 pm
Hey Longrider, that's a nice Bull !

Rod
Thanks! This year was very special, my son and grandson didn’t have tags but they were able to join me for a week during general bull this year. I passed on a few small bulls earlier not knowing that they were coming and so glad I did!

I racked up this bull with both of them at my side after some long days. It was a very long night and tough back pack out.

Now they understand why the old man says he is whipped after packing out elk! We don’t road hunt and it is all gen season public NF so you have to get after it.

Nice to have them as my mules to share the load - best relational memories are often related to hard work.
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Re: Terminal Performance

Post by stokesrj » Sun Jan 13, 2019 10:48 am

stokesrj wrote:
Sat Jan 12, 2019 2:26 pm
The short barrel 308 project has stemmed some further research on the possible terminal effects of the various bullets this rifle shoots well. Of primary concern is the low impact velocity at range so I've been focusing on highly frangible bullets that will have a higher likelihood of quicker kills when ranges are long and velocities are low. To achieve this result the bullet must be designed with a thin jacket and wide meplat and of course this brings into question the close range, higher impact velocity performance of such a fragile (soft) bullet.

All bullets have a lower impact velocity threshold below which the bullet behaves as a solid with excessive penetration and a narrow wound channel. All bullets also have an upper impact velocity threshold above which the mass of the bullet is shed so quickly that penetration is compromised, creating a wide shallow wound that may fail to reach the vital organs.

The first bullet up for study is the Hornady # 30506 ELD Match bullet. My rifle likes this bullet and the Hornady Superformance Match factory load. This is my fall back loading in case I am unable to handload. It typically shoots 1/2 to 5/8 MOA from my 16.5" suppressed R8 barrel. And produces a muzzle velocity of approximately 2650 FPS which is very good for a short barrel. It took me several months to find a handload that would match and then surpass this level of performance so it is in my opinion a very good factory load.

The # 30506 ELD Match bullet is a simple cup and core, secant ogive, boat tail design with a polymer tip .308' diameter and weighing 168 grains. The gilded copper jacket is non tapered and is .020" thick. The polymer tip is 0.100" wide where it meets the jacket and the jacket opening forms a 0.090" hollow point which is filled with the stem of the polymer tip and promotes rapid fragmentation and expansion. The bullet is 1.270" log and 0.650" from base to ogive. Hornady lists the BC as .523 G1 and .263 G7 but this is true at high velocities only. If you dig into their more detailed data you will find that those ballistic coefficients were measured by doppler radar at mach 2.5 which is approximately 2,800 fps. When the velocity falls to mach 2 then the BC also falls to .516 G1 and .259 G7 and then at mach 1.75 it is .498 G1 and .251 G9.

The sectional density of a 168 grain .308 bullet made of a lead core and gilded copper jacket is .253. I believe this is important in that the 168 grain weight provides enough mass to insure adequate penetration for deer to elk sized game even with this high fragmentation designed bullet.

For the purposes of this test I have chosen to use bare 10% ballistic gel calibrated to the FBI standard. I realize it does not perfectly match the complex construction of a living animal with hide, muscle and sinew. However I have done enough tests with this medium and compared the results to live game that I think it is a relatively close match. Meaning that bullets I have recovered from game penetrated similar depths and look much the same as bullets recovered from the gel.

So here is a pic of the cross section of this bullet that I cut in half and photographed to give you a visual image of the construction of this bullet to match the dimensions listed above. OTxQOncGQLuzhkZimTcO7A.jpg
After cross sectioning the bullet I also loaded some reduced loads to simulate mid, 300-400 yards, long range, 600-700 yards and then lower velocities to find a velocity that the bullets failed to expand. I chose to use H4895 powder for this purpose because it is a proven reduced load powder. Trailboss is also good for reduced loads but even the max loading of 15 grains produced no expansion and was difficult to capture a bullet. Penetration was in excess of 48".

First up is the testing at close range the most severe test for this bullet with an impact velocity from this rifle of 2625 fps.
High fragmentation, and 17.5" of penetration resulted in a very wide violent wound channel that would be devastating to any deer or elk on a broad side rib cage shot. Surprisingly the jacket and core did not separate and weighed 100.7 grains for 60% retained weight retention.OTxQOncGQLuzhkZimTcO7A.jpg
Thanks Brad,

That is some good information. There is no denying the results you have had with SMKs and Sceenars. I think I related to you before the bad experience I had with SMK's out of a .338 Win Mag on Caribou, that was many years ago (1976) and perhaps a different jacket harness than what exists now. Those bullets took odd paths that missed the vital organs and acted as solids at only 200-250 yards. So you can see why I've been leery of match bullets for use on big game ever since, but your results are stellar.

The one pic you have of the separated core and jacket is what many refer to as a failure. I don't as I've recovered too many like that from dead animals and it is obvious that the jacket and core did not part ways until after doing their job in the vital organs. Also with my ballistic gel testing I find that most often the bullet and jacket separation occurs only at the very end of the bullet path when the jacket is slowing down much faster than the core wants to go and they pull apart, I often find them touching or less than an inch apart. The same was true on the cow elk my daughter-in-law Cati shot this fall. It was a big mature cow elk called in and walking straight to her. She took the shot with a 6.5 Grendel I built for her at only 40 yards dead center of the chest just below the throat. The 123 grain Hornady SST went all the way through the thorax and stopped in the stomach where the bullet and core were laying almost touching in the stomach contents. That bullet destroyed both lungs and the cow only went 50-60 yards before going down in sight. Yet I see many pictures of this kind of performance and the internet experts declare it a failure and advise to move to a bonded or tougher bullet. I just smile with amusement.

I am also testing the 168 grain Sierra Tipped Match King and the 165 grain Tipped Game King (Gamechanger). Both have a larger diameter polymer tip which should promote more rapid energy transfer than the standard Match King or Game King. You may find those results interesting.
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Re: Terminal Performance

Post by longrider » Sun Jan 13, 2019 8:59 pm

Robert
Correct in mine not being science - but what you describe as bullet failure is where we part company. The shot was 571 yards on a mature bull. As described above, nice direct path (he was bedded at an angle below me) took out the vitals and the fragments pictured were lodged in the offside elbow.

He died so quickly that he dropped his chin on the ground and rolled over without some much as a leg kick. I will take the failure everytime when they all die without taking a step.

I get it about bad experience. I wouldn’t use them either if I had the issues you describe. Confidence is a huge part of what we choose to utilize.
Brad

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Re: Terminal Performance

Post by stokesrj » Sun Jan 13, 2019 9:26 pm

Hi Brad, I think you misunderstood, If you read my comment more carefully you will see that I said what others call a bullet failure, I don't consider a bullet that kills cleanly a failure.
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Re: Terminal Performance

Post by stokesrj » Mon Jan 14, 2019 12:11 pm

Sierra #7768 .308" 168 grain Tipped Match King.
Diameter - .308"
Weight - 168 grains
Length - 1.330"
Base to Ogive - .620"
G1 BC - .535
Jacket Thickness - .020"
Tip Diameter - .145"
Hollow Point Diameter - .010

Penetration at 2600 FPS - 17.5"
Retained Weight at 2600 FPS - 95.1 grains
Retained Weight % at 2600 FPS - 56.6%
Core Separation at 2600 FPS - Yes but Jacket and core were touching at end of track
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Re: Terminal Performance

Post by stokesrj » Mon Jan 14, 2019 12:28 pm

Sierra #4665 .308" 165 grain Tipped GameKing.
Diameter - .308"
Weight - 165 grains
Length - 1.405"
Base to Ogive - .775"
G1 BC - .530
Jacket Thickness - .050"-.018"
Tip Diameter - .145"
Hollow Point Diameter - .010

Penetration at 2600 FPS - 27.5"
Retained Weight at 2600 FPS - 143.7 grains
Retained Weight % at 2600 FPS - 87.1%
Core Separation at 2600 FPS - No
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Re: Terminal Performance

Post by stokesrj » Mon Jan 14, 2019 12:31 pm

Most people would look at the 165 Tipped GameKing as the superior hunting bullet. At one time I would have also, but today I see the 168 grain Tipped Game King or 168 grain ELDM as a superior bullet for fast kills. As I complete the testing and show the results of these bullets at medium range, 2200 fps impact and long range 2,000 fps impact the reasons why will become more clear.
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Re: Terminal Performance

Post by Gun Barrel Ecologist » Mon Jan 14, 2019 3:16 pm

Interesting thread

Curious to see if a 165g SST will get subject to the same test.

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Re: Terminal Performance

Post by stokesrj » Mon Jan 14, 2019 7:07 pm

Gun Barrel Ecologist wrote:
Mon Jan 14, 2019 3:16 pm
Interesting thread

Curious to see if a 165g SST will get subject to the same test.
I do plan to test the 165 SST in the future. I had chosen it to study penetration depths of the various weights since it comes in 125, 150, 165 and 180 grain weights. It may be a while as the testing gets time consuming it takes three days per test for the gel preparation cycle with the equipment I have.

In the meantime, I do have two SST bullets recovered from game. They are both the 123 grain 6.5mm SST fired from my 6.5 Grendels. In the picture is one I took from a wild boar shot at 50 yards at a steep raking angle entering just in front of the right rear leg and stopping on the left shoulder hide. It penetrated approximately 24" and killed the boar quickly. Flight distance was approximately 15 yards. The far right bullet was recovered in the stomach of an elk my daughter in law shot at 40 yards facing her. It penetrated approximately 30" and also produced a quick kill. Flight distance was 50-60 yards and it went down in sight. Elapsed time under 10 seconds from hit to down. As you can see the locking mechanism of the SST doesn't always work but the jacket and core were found within and inch of one another so separation did not occur until after the work of destroying both lungs and the liver had been accomplished.
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Re: Terminal Performance

Post by ebrownw2 » Mon Jan 14, 2019 7:31 pm

Last month I shot a whitetail doe with my R8 308 win 16.5” barrel with my silencerco suppressor attached using the Hornady Superformance 168 grain ELD match ammo. It was just a 200 yard shot so perhaps the info is not relevant to this conversation, but for what it is worth I shot her at the top of the shoulder and she ran about 20 yards before expiring.

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Re: Terminal Performance

Post by stokesrj » Mon Jan 14, 2019 7:38 pm

Thanks Eddie,
When you say top of the shoulder, did the bullet hit any of the back bone, did the bullet exit, any pieces recovered?
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Re: Terminal Performance

Post by Perdizhunter » Mon Jan 14, 2019 7:47 pm

Robert
SST are my preference in .308 Win . I’m a hog hunter , and killed a lot of hogs with SST 180 grains , using my .308s.
In a short barreled rifle , like my Benelli R1 , that suffer a bit with velocity ( 2450 ft/sec) due short barrel , SST works flawlessly with excelent expansion , no core separation ( around 1% of core separation of recovered bullets )
SST has a abrupt expansion , so my preference is 180 grains to maintain velocity under control and avoid lots of core separation
In a short barreled rifle , in my opinion , with lots of hogs killed using SST , I believe that SST is hard to beat.

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