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Discussion Starter · #1 ·
Anyone have any experience or data on what they would consider the maximum effective range for the 6.8 with either the 95 grain TTSX or the 105 grain MKZ?

I know I have heard the comparison of the 6.8 to a 30 30 and that seems to be with the shorter barrels. I have a 20" that is lights out with the 105 MKZ and 29 grains of 2200 and when I look at the ballistic comparison it seems to be shooting much close to a 243 with a 105 grain pill and IMR 4831 which is what I have. Would that be a fair assessment?

If that is the case, with good shot placement and a 20" barrel it seems like there would be sufficient velocity to drop a deer fairly easily at 300+ yards correct?
 

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Here's the longer version you may find helpful...

 

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The bullet performance section greentick sent you to is spot on or at least as close as you can get to what you can expect on game with each bullet tested . I know that for a fact because we have taken game with almost every one he tested. The cbb105 load you shoot is my favorite out of my 12.5 " and 18" and they definitely work . As far as performance you could go out to 400 yards but I prefer to keep shots around 300 or less even with more powerful guns .

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Discussion Starter · #6 ·
Here's the longer version you may find helpful...

This is awesome, thanks!
 

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Discussion Starter · #7 ·
The bullet performance section greentick sent you to is spot on or at least as close as you can get to what you can expect on game with each bullet tested . I know that for a fact because we have taken game with almost every one he tested. The cbb105 load you shoot is my favorite out of my 12.5 " and 18" and they definitely work . As far as performance you could go out to 400 yards but I prefer to keep shots around 300 or less even with more powerful guns .

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Good to know! I agree with you on keeping the shots close and 99% of the time for me it's going to be inside of 50 yards so it's really more of an academic discussion for curiosity.

Thanks
 

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Agree 400 maybe edgy, but doable out of 20" ARPs like ours, with the 105 MKZs. Haven't tried them yet to chrono them. Calculator puts them at 918 FPE & 1984 FPS at 400 yards if the elevation is 5600. That's using the BC .318 G1 that Xman measured, if you can hit the 2850 out of a 20". Those numbers are well above the claimed low threshold for the 105 MKZ by CCB. The PBR with a 250' zero is just shy of the 300 yard mark.

At sea level they are definitely GTG at the OP's hoped for 300 yards turning in similar numbers as our 400 yards.
 

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Discussion Starter · #9 ·
Agree 400 maybe edgy, but doable out of 20" ARPs like ours, with the 105 MKZs. Haven't tried them yet to chrono them. Calculator puts them at 918 FPE & 1984 FPS at 400 yards if the elevation is 5600. That's using the BC .318 G1 that Xman measured, if you can hit the 2850 out of a 20". Those numbers are well above the claimed low threshold for the 105 MKZ by CCB. The PBR with a 250' zero is just shy of the 300 yard mark.

At sea level they are definitely GTG at the OP's hoped for 300 yards turning in similar numbers as our 400 yards.
Thanks for the data that helps!
 

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Does anyone remember When Mark Larue took an Elk at 425 Yards with his 6.8 ? I don't remember what bullet he used.
 

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When I designed both the 105 grain and 120 grain MKZ's there were 5 goals.
Low speed expansion threshold
High total expansion
Increase the effective range of the 6.8 SPC
Accuracy
Consistent reliable expansion each and every time ( unlike the 95gr TTSX, the failures of which led the the creation of the MKZ's)

Additionally to also dump all the energy in the game creating a larger temporary and permanent wound channel.
While also exiting to create a blood trail.
Very lofty goals to ask of a projectile.

The result is a projectile that gets double caliber expansion and retains 750 lb-ft of energy at extended range over existing 6.8 projectiles.
The focus was out of 16 inch 6.8 barrels. Although they increase the 6.8's performance from any barrel length.
The 120 grain MKZ will do this to 450 yards out of a 16in barrel at 2500 fps at the muzzle.
The 105 grain MKZ will do this to 425 yards out of a 16in barrel at 2750 fps at the muzzle.
This is at sea level, distances can increase as altitude increases.
From coyote to elk the MKZ's have been proving themselves for over 4 years now.
I personally would take the shot at 500 yards with the 120 grain MKZ if I was positive I could make the shot.

If the shooter is capable of the shot they will do the job to these distances on medium body game on down.
I was tired of the Grendel crowd touting its ability to be effective at longer ranges than the 6.8. The MKZ's leveled that playing field.
In fact now with the comparison of the 118 grain 6.5 MKZ to the 120 grain 6.8 MKZ the 6.8 betters the 6.5 by 25 yards.
 

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When I designed both the 105 grain and 120 grain MKZ's there were 5 goals.
Low speed expansion threshold
High total expansion
Increase the effective range of the 6.8 SPC
Accuracy
Consistent reliable expansion each and every time ( unlike the 95gr TTSX, the failures of which led the the creation of the MKZ's)

Additionally to also dump all the energy in the game creating a larger temporary and permanent wound channel.
While also exiting to create a blood trail.
Very lofty goals to ask of a projectile.

The result is a projectile that gets double caliber expansion and retains 750 lb-ft of energy at extended range over existing 6.8 projectiles.
The focus was out of 16 inch 6.8 barrels. Although they increase the 6.8's performance from any barrel length.
The 120 grain MKZ will do this to 450 yards out of a 16in barrel at 2500 fps at the muzzle.
The 105 grain MKZ will do this to 425 yards out of a 16in barrel at 2750 fps at the muzzle.
This is at sea level, distances can increase as altitude increases.
From coyote to elk the MKZ's have been proving themselves for over 4 years now.
I personally would take the shot at 500 yards with the 120 grain MKZ if I was positive I could make the shot.

If the shooter is capable of the shot they will do the job to these distances on medium body game on down.
I was tired of the Grendel crowd touting its ability to be effective at longer ranges than the 6.8. The MKZ's leveled that playing field.
In fact now with the comparison of the 118 grain 6.5 MKZ to the 120 grain 6.8 MKZ the 6.8 betters the 6.5 by 25 yards.
Great job I need to get some of your bullets but right now i have 2 cases of Hornady 120gr SST and my 18'' ARP Barrel shoots avg .500'' of an inch and my avg Velocity is 2567FPS so it might be a little while but i will get some. Right now im very pleased with the 120gr SST it has done its job on coyotes and Whitetail's.
 

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When I designed both the 105 grain and 120 grain MKZ's there were 5 goals.
Low speed expansion threshold
High total expansion
Increase the effective range of the 6.8 SPC
Accuracy
Consistent reliable expansion each and every time ( unlike the 95gr TTSX, the failures of which led the the creation of the MKZ's)

Additionally to also dump all the energy in the game creating a larger temporary and permanent wound channel.
While also exiting to create a blood trail.
Very lofty goals to ask of a projectile.

The result is a projectile that gets double caliber expansion and retains 750 lb-ft of energy at extended range over existing 6.8 projectiles.
The focus was out of 16 inch 6.8 barrels. Although they increase the 6.8's performance from any barrel length.
The 120 grain MKZ will do this to 450 yards out of a 16in barrel at 2500 fps at the muzzle.
The 105 grain MKZ will do this to 425 yards out of a 16in barrel at 2750 fps at the muzzle.
This is at sea level, distances can increase as altitude increases.
From coyote to elk the MKZ's have been proving themselves for over 4 years now.
I personally would take the shot at 500 yards with the 120 grain MKZ if I was positive I could make the shot.

If the shooter is capable of the shot they will do the job to these distances on medium body game on down.
I was tired of the Grendel crowd touting its ability to be effective at longer ranges than the 6.8. The MKZ's leveled that playing field.
In fact now with the comparison of the 118 grain 6.5 MKZ to the 120 grain 6.8 MKZ the 6.8 betters the 6.5 by 25 yards.
Nice. Well there you go. Thanks Yamaraja.

Now I will have to get some soon to be able to play with them before this fall. Was planning on the 105s because you can get the velocity up to be sure they function. Now I know that at our elevation the 120s maybe good to 500? Guess I will be getting some of those too. 😁
 

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When I designed both the 105 grain and 120 grain MKZ's there were 5 goals.
Low speed expansion threshold
High total expansion
Increase the effective range of the 6.8 SPC
Accuracy
Consistent reliable expansion each and every time ( unlike the 95gr TTSX, the failures of which led the the creation of the MKZ's)

Additionally to also dump all the energy in the game creating a larger temporary and permanent wound channel.
While also exiting to create a blood trail.
Very lofty goals to ask of a projectile.

The result is a projectile that gets double caliber expansion and retains 750 lb-ft of energy at extended range over existing 6.8 projectiles.
The focus was out of 16 inch 6.8 barrels. Although they increase the 6.8's performance from any barrel length.
The 120 grain MKZ will do this to 450 yards out of a 16in barrel at 2500 fps at the muzzle.
The 105 grain MKZ will do this to 425 yards out of a 16in barrel at 2750 fps at the muzzle.
This is at sea level, distances can increase as altitude increases.
From coyote to elk the MKZ's have been proving themselves for over 4 years now.
I personally would take the shot at 500 yards with the 120 grain MKZ if I was positive I could make the shot.

If the shooter is capable of the shot they will do the job to these distances on medium body game on down.
I was tired of the Grendel crowd touting its ability to be effective at longer ranges than the 6.8. The MKZ's leveled that playing field.
In fact now with the comparison of the 118 grain 6.5 MKZ to the 120 grain 6.8 MKZ the 6.8 betters the 6.5 by 25 yards.
6.5 Grendel doesn't really outrange 6.8 SPC in terms of expansion threshold because both produce velocities within 75 FPS out to 500 yards. Neither has enough velocity or energy for use on game at ranges beyond that with even the best loads.

Also, I suspect the 6.5 projectiles need a tad more velocity to achieve the same expansion diameter. In fact, if you watch Brass Fetcher's high speed camera and when you look at their actual KE transfer measurements (using load cells below the gel blocks), you can clearly see the pressure wave is much more rapid with 6.8 SPC vs. 6.5 Grendel. During the test, they all used Barnes TSX monolithic bullets, so it's about as fair as you can get.

Everyone seems to forget the reality that bullets that have low drag while flying through the air also have lower drag while passing through soft tissue....they don't suddenly have more drag when impacting the target than larger diameter projectiles. Thus they need higher velocity to produce similar resistance forces that cause expansion when comparing projectiles of the same material. Often that little extra velocity is necessary just to achieve the same performance as a slightly larger projectile.

This would explain why they perform fairly similar on soft targets. The below data is measured data, not theoretical. The US military in the 2008 Gary Roberts report found the same thing, bigger bullets produce more damage to the target, but give up more velocity at longer ranges making them harder to actually shoot.

Go too far in either direction an you give up too much in one metric or another. Too large of a diameter with a given case volume and you loose too much velocity, too small of a diameter and you cede too much in terminal performance. At achievable velocities in these case sizes, .270 cal is the ideal balance and at this point it's well proven. With a bigger case, that might change depending on the intended ranges / targets.

71750


71751


71752


Look at the actual data comparing all four calibers. Excluding .50 Beowolf because it has NO ranged use compared tot he other three, 6.8 is by far the best performer. With direct hits and through intermediate barriers, it delivers nearly 33% more peak energy and early on, which is responsible for causing further damage to tissue already torn by the projectile physically crushing / tearing it as is passes through.

This secondary remote damage effect is caused by the hydraulic pressure wave which follows immediate behind the projectile in it's path. It is an important factor in how rifle rounds deliver DRT performance. Pretty hard to argue when looking at the evidence. 6.5 Grendel loads simply do not provide the same barrier blind performance nor do they provide the same peak pressure.

I'm not suggesting they are not lethal, I'm not suggesting they aren't superior to 5.56 in some ways (especially at intermediate ranges), however they simply don't deliver the performance 6.8 mm projectiles.

It might seem unbelievable, but the small differences in shape (length vs. diameter) actually makes a significant real world differences in how the projectiles behave terminally. It seems that the difference between 6.5 mm and 6.8 mm is a threshold at these velocities. 7mm and 7.62mm prove even more destructive than 6.8mm on target, but again we go back to drift, drop and retained velocity at intermediate ranges and that's where 7mm and 7.62mm give up too much for this case size.

Obviously that's not the case when talking about much larger case volumes in say Remington 7mm Magnum or 7.62x51 NATO (aka .308).
 

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Anyone have any experience or data on what they would consider the maximum effective range for the 6.8 with either the 95 grain TTSX or the 105 grain MKZ?

I know I have heard the comparison of the 6.8 to a 30 30 and that seems to be with the shorter barrels. I have a 20" that is lights out with the 105 MKZ and 29 grains of 2200 and when I look at the ballistic comparison it seems to be shooting much close to a 243 with a 105 grain pill and IMR 4831 which is what I have. Would that be a fair assessment?

If that is the case, with good shot placement and a 20" barrel it seems like there would be sufficient velocity to drop a deer fairly easily at 300+ yards correct?
Placement of the bullet on target is key !

I would feel comfortable out to 450-500 yards, with any load, in a rifle that I had complete confidence in.
 

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Discussion Starter · #17 ·
6.5 Grendel doesn't really outrange 6.8 SPC in terms of expansion threshold because both produce velocities within 75 FPS out to 500 yards. Neither has enough velocity or energy for use on game at ranges beyond that with even the best loads.

Also, I suspect the 6.5 projectiles need a tad more velocity to achieve the same expansion diameter. In fact, if you watch Brass Fetcher's high speed camera and when you look at their actual KE transfer measurements (using load cells below the gel blocks), you can clearly see the pressure wave is much more rapid with 6.8 SPC vs. 6.5 Grendel. During the test, they all used Barnes TSX monolithic bullets, so it's about as fair as you can get.

Everyone seems to forget the reality that bullets that have low drag while flying through the air also have lower drag while passing through soft tissue....they don't suddenly have more drag when impacting the target than larger diameter projectiles. Thus they need higher velocity to produce similar resistance forces that cause expansion when comparing projectiles of the same material. Often that little extra velocity is necessary just to achieve the same performance as a slightly larger projectile.

This would explain why they perform fairly similar on soft targets. The below data is measured data, not theoretical. The US military in the 2008 Gary Roberts report found the same thing, bigger bullets produce more damage to the target, but give up more velocity at longer ranges making them harder to actually shoot.

Go too far in either direction an you give up too much in one metric or another. Too large of a diameter with a given case volume and you loose too much velocity, too small of a diameter and you cede too much in terminal performance. At achievable velocities in these case sizes, .270 cal is the ideal balance and at this point it's well proven. With a bigger case, that might change depending on the intended ranges / targets.

View attachment 71750

View attachment 71751

View attachment 71752

Look at the actual data comparing all four calibers. Excluding .50 Beowolf because it has NO ranged use compared tot he other three, 6.8 is by far the best performer. With direct hits and through intermediate barriers, it delivers nearly 33% more peak energy and early on, which is responsible for causing further damage to tissue already torn by the projectile physically crushing / tearing it as is passes through.

This secondary remote damage effect is caused by the hydraulic pressure wave which follows immediate behind the projectile in it's path. It is an important factor in how rifle rounds deliver DRT performance. Pretty hard to argue when looking at the evidence. 6.5 Grendel loads simply do not provide the same barrier blind performance nor do they provide the same peak pressure.

I'm not suggesting they are not lethal, I'm not suggesting they aren't superior to 5.56 in some ways (especially at intermediate ranges), however they simply don't deliver the performance 6.8 mm projectiles.

It might seem unbelievable, but the small differences in shape (length vs. diameter) actually makes a significant real world differences in how the projectiles behave terminally. It seems that the difference between 6.5 mm and 6.8 mm is a threshold at these velocities. 7mm and 7.62mm prove even more destructive than 6.8mm on target, but again we go back to drift, drop and retained velocity at intermediate ranges and that's where 7mm and 7.62mm give up too much for this case size.

Obviously that's not the case when talking about much larger case volumes in say Remington 7mm Magnum or 7.62x51 NATO (aka .308).
This is some awesome data! Thanks for providing it!
 

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Discussion Starter · #18 ·
Placement of the bullet on target is key !

I would feel comfortable out to 450-500 yards, with any load, in a rifle that I had complete confidence in.
Agreed and it seems like the 6.8 has no trouble doing the job if proper shot placement is achieved!
 

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When I designed both the 105 grain and 120 grain MKZ's there were 5 goals.
Low speed expansion threshold
High total expansion
Increase the effective range of the 6.8 SPC
Accuracy
Consistent reliable expansion each and every time ( unlike the 95gr TTSX, the failures of which led the the creation of the MKZ's)

Additionally to also dump all the energy in the game creating a larger temporary and permanent wound channel.
While also exiting to create a blood trail.
Very lofty goals to ask of a projectile.

The result is a projectile that gets double caliber expansion and retains 750 lb-ft of energy at extended range over existing 6.8 projectiles.
The focus was out of 16 inch 6.8 barrels. Although they increase the 6.8's performance from any barrel length.
The 120 grain MKZ will do this to 450 yards out of a 16in barrel at 2500 fps at the muzzle.
The 105 grain MKZ will do this to 425 yards out of a 16in barrel at 2750 fps at the muzzle.
This is at sea level, distances can increase as altitude increases.
From coyote to elk the MKZ's have been proving themselves for over 4 years now.
I personally would take the shot at 500 yards with the 120 grain MKZ if I was positive I could make the shot.

If the shooter is capable of the shot they will do the job to these distances on medium body game on down.
I was tired of the Grendel crowd touting its ability to be effective at longer ranges than the 6.8. The MKZ's leveled that playing field.
In fact now with the comparison of the 118 grain 6.5 MKZ to the 120 grain 6.8 MKZ the 6.8 betters the 6.5 by 25 yards.
What powder do you use to get 2750 at the muzzle from a 16" barrel? With 28.9grn of 2200, 1:11 ,4 grove BBL I was getting 2609. temp. was 48F. @ 4270 ft elevation
 

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What powder do you use to get 2750 at the muzzle from a 16" barrel? With 28.9grn of 2200, 1:11 ,4 grove BBL I was getting 2609. temp. was 48F. @ 4270 ft elevation
A load of 2200 just a shade more than your load gives me 2700 out of 16" ARP 5r groove . Different barrels and chambers get different results. My loads are not max and show no pressure signs of over pressure so I could probably reach 2750 without getting to hot if I chose to .

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