If you want it to hit hard get a 20" barrel. I would stick with 120 gr. or heavier. I have hunted and shot critters with this round. I am not impressed with the combination of 110 gr. ammo and 16" barrel. I like the SSA TAC loads that are hotter.
6.8 SPC questions
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Float Pilot
Member
Go find the 6.8mm forum...
http://68forums.com/forums/forum.php
http://68forums.com/forums/forum.php
I guess our idea of negligible is different.
I used the above load from your example because that is similar to my go-to in a 16" barrel right now. Just under 300 FPS is a great velocity increase, but we are talking about 8" of barrel.
The OP was asking about 16, 18, or 20" options, and I still maintain that the difference in downrange affect won't be a whole lot and it boils down to personal preference. I love the long tube numbers, a 110 grain bonded bullet at over 3K is great from an AR15. I personally don't have much desire to walk around with one though and will settle for 2750. Everyone's mileage may vary.
Potatohead
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The more I read about the Grendel, the better it sounds.
I would say the prose about a particular cartridge is just that. Some get fans who like to talk about them. Others get fans who like to shoot them.
If someone is looking for a cartridge that has "stopping" power, I can say with the same authority using similar one shot anecdotes that the .308 is a weak round, and the .30-06 even less capable. I've shot deer with them both, they moved downslope every time, and they didn't just drop dead right there. To my exhaustion pulling them back uphill.
Shot placement has more to do with it than caliber, and bullet construction a lot to do with dumping the energy into the deer fast enough to disrupt blood vessels and cause it to bleed out. Blaming one cartridge or another by measurement cannot nor will not correct the poor choice in bullet and point of aim.
It's already been noted and documents, both the 6.8 and 6.5 can take down elk sized game at over 400 yards - by expert shooters. And bluntly, most can't. It's a long odds shot in the field to begin with, the bullet simply doesn't retain as much energy as we would like, and the point of impact can't deviate more than a few inches. Shooting "at the chest" is far too much area when the heart only covers about a 6" circle. All the rest is lungs, and at the much slower rate of bleeding out, the animal could easily have from two minutes to two hours before finally expiring.
If you need to anchor them dead in their tracks - a goal many hunters have tried to accomplish for centuries - keep looking. I would suggest the .50 BMG cut down to accept 12 ga slugs. If you can get decent expansion at 500 yards, then go for it. Otherwise, it's a fruitless mission. NOBODY is guaranteed a one shot drop in it's tracks cartridge. The closest I have seen in the field was the 8mm Magnum - and it's no fun to shoot at all.
I'm not one to argue ballistics and statistics to make a point, that's basically internet commando talk. The reality is what was already explained - out to 300 meters, the 6.8SPC has it's niche. You can force other cartridges in short barreled guns to try to compete, but they were never intended for the role, and they don't do the same job because of it. Each one was designed for a particular purpose, research the origins and you begin to understand the reasons behind the case shape, bullet length, and what the inventors were attempting to reach as a goal.
If I was night hunting hogs in Texas, I would appreciate a suppressed .300BO. Deer in MO, a 16" 6.8. Antelope out west, a 6.5, and frankly, I would think it inappropriate to bring the others. The cartridge is the tool to select for the job by what it does best - not what it can be twisted to do with "enhancements" that actually force it into a role it was never suited.
If someone is looking for a cartridge that has "stopping" power, I can say with the same authority using similar one shot anecdotes that the .308 is a weak round, and the .30-06 even less capable. I've shot deer with them both, they moved downslope every time, and they didn't just drop dead right there. To my exhaustion pulling them back uphill.
Shot placement has more to do with it than caliber, and bullet construction a lot to do with dumping the energy into the deer fast enough to disrupt blood vessels and cause it to bleed out. Blaming one cartridge or another by measurement cannot nor will not correct the poor choice in bullet and point of aim.
It's already been noted and documents, both the 6.8 and 6.5 can take down elk sized game at over 400 yards - by expert shooters. And bluntly, most can't. It's a long odds shot in the field to begin with, the bullet simply doesn't retain as much energy as we would like, and the point of impact can't deviate more than a few inches. Shooting "at the chest" is far too much area when the heart only covers about a 6" circle. All the rest is lungs, and at the much slower rate of bleeding out, the animal could easily have from two minutes to two hours before finally expiring.
If you need to anchor them dead in their tracks - a goal many hunters have tried to accomplish for centuries - keep looking. I would suggest the .50 BMG cut down to accept 12 ga slugs. If you can get decent expansion at 500 yards, then go for it. Otherwise, it's a fruitless mission. NOBODY is guaranteed a one shot drop in it's tracks cartridge. The closest I have seen in the field was the 8mm Magnum - and it's no fun to shoot at all.
I'm not one to argue ballistics and statistics to make a point, that's basically internet commando talk. The reality is what was already explained - out to 300 meters, the 6.8SPC has it's niche. You can force other cartridges in short barreled guns to try to compete, but they were never intended for the role, and they don't do the same job because of it. Each one was designed for a particular purpose, research the origins and you begin to understand the reasons behind the case shape, bullet length, and what the inventors were attempting to reach as a goal.
If I was night hunting hogs in Texas, I would appreciate a suppressed .300BO. Deer in MO, a 16" 6.8. Antelope out west, a 6.5, and frankly, I would think it inappropriate to bring the others. The cartridge is the tool to select for the job by what it does best - not what it can be twisted to do with "enhancements" that actually force it into a role it was never suited.
Float Pilot
Member
That is very true....
I mistakenly thought you were repeating the often repeated myth that the 6.8mm only works from short barrels. A claim the 6.5mm Grendel folks like to shout. I specifically built the 24 inch AR just to see how true that was... And as you see the velocity gain is about the same as a 30-06 or 308 per inch.
For critters like Caribou, Mountain Goats, Deer, and black bear my personal lower limit for a cartridge like this is 2,000 fps remaining velocity at bullet impact and at least 1,000 foot pounds of energy.
In the above sample of the 110gr Nolser Accubond;;;
the 16 inch barrel gives me that at 325 yards
the 20 inch barrel moves that out to 375 yards
the 24 inch barrel gives me that at 425 yards.
I have though about cutting my 24 inch Black Hole barrel back to 22 inches for balance purposes. The real gain with the long barrel comes from the heavier bullets like the 150 grain round nose. The shorter barrel is so slow that you have marginal velocity from the muzzle. The extra 300 fps from my long-rifle at least gives that bullet enough zoom that it makes a good little thumper within 150 yards.
6.8 is pretty similar to 7.62x39 the difference being you get about 4 times the ammo for the money with x39. Where we hunt this round is only a fair option, useful if you must, but there are better choices. I would not seriously attempt a 425 yd shot unless some close kin were hungry. The furthest I would feel comfortable would be 250 with a full expectation of needing at least one follow up shot. I'm hunting now with an 18" barrel MP10 and using max safe loads of 150 gr. SST. I feel that this combo has the "diesel". Adding: case capacity of 6.8 is 34.8 gr. water while 7.62x39 is 35.5 gr.
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JRH6856
Member
FWIW, the measured case capacity of my 6.8 SSA brass is 37.03gr H20
His listed 6.8 capacity is accurate. http://68forums.com/forums/showthread.php?38411-Case-Capacity-Experiment
Can't speak to x39, though SAAMI allows another 10k pressure to the 6.8.
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Which brings up the issue of measuring the velocity from different barrels - you have to use the exact same ammo to get any reliable data.
So, if someone can get more velocity from a longer barrel, why not handload a hotter cartridge to make up the difference in the shorter ones? Which many can and have done. They bought a barrel with rifling that supports the end goal of more speed, selected the components, and have tested with chronograph speeds past 3,000 fps with the 6.8.
You don't have to use a longer barrel, you can use better ammo. SAMMI pressures are a critical area of controversy with 6.8 - the round initially got limited due to a defect in the drawing submitted, and we've been fighting that issue for over ten years now. It's why the corrected round and spec is called SPC II - because it's the originally designed spec enhanced even further.
If your barrel and ammo combination won't tolerate it, sorry, but there are others who can take things to that level and still enjoy the 16" barrel length. There's more to velocity than is being presented in the thread, and it's actually old news for 6.8 shooters.
So, if someone can get more velocity from a longer barrel, why not handload a hotter cartridge to make up the difference in the shorter ones? Which many can and have done. They bought a barrel with rifling that supports the end goal of more speed, selected the components, and have tested with chronograph speeds past 3,000 fps with the 6.8.
You don't have to use a longer barrel, you can use better ammo. SAMMI pressures are a critical area of controversy with 6.8 - the round initially got limited due to a defect in the drawing submitted, and we've been fighting that issue for over ten years now. It's why the corrected round and spec is called SPC II - because it's the originally designed spec enhanced even further.
If your barrel and ammo combination won't tolerate it, sorry, but there are others who can take things to that level and still enjoy the 16" barrel length. There's more to velocity than is being presented in the thread, and it's actually old news for 6.8 shooters.
I dont mean to say 6.8 spc is a bad cartridge and the rifles are usually great, being accurate AR designs. I was just trying to give perspective for what the round can do. For woods, southern rough, or anything out to 250 its going to get the job done. Its a good idea to reload for this cartridge so you can seat the bullets out to max OAL the mag allows, thereby allowing for more powder room. There are lots of good loads that have been developed by reloaders in this respect. I would recommend the 20" barrel, spec 2 for added velocity. Admittedly I have only used this round on two deer and some prairie dogs. Happy hunting!
Arizona_Mike
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In designing the 6.8, the military was looking at FMJ effectiveness. By many accounts, they found 7mm to be the hardest hitting within 300 yards, the 6.5 to have the best long range performance and the 6.8mm was a compromise for a 500 yard optimum.
It is interesting to see the lineage from the .30 Remington (which served as the parent case for 10mm Auto and .40 S&W) and the .277" bullet from the 7mm Chinese Mauser which came to us through the .270 Winchester.
Civilians can use expanding 6.5mm ammo which changes the calculation IMHO.
For short range/hard hitting, I'd like to see the 7.62x45WT become more popular but I doubt it will happen.
Mike
It is interesting to see the lineage from the .30 Remington (which served as the parent case for 10mm Auto and .40 S&W) and the .277" bullet from the 7mm Chinese Mauser which came to us through the .270 Winchester.
Civilians can use expanding 6.5mm ammo which changes the calculation IMHO.
For short range/hard hitting, I'd like to see the 7.62x45WT become more popular but I doubt it will happen.
Mike
JRH6856
Member
Make sure you read that thread to the end. His second round of testing produced different results. In the first round, it is not clear to what point the cases were filled as he says he "eyeballed" it. In the second round, the cases were fireformed before testing and it is not clear whether or not they were resized before testing. As a result, I'm not sure what either set of results tell us other than a ballpark figure.
I only tested SSA brass, once fired, resized and trimmed to uniform length. Used primers were seated upside down with a small disk of plastic punched out with hole punch on top to create a flat surface over the FP dimple. I used a similar method as described for his second round, using a syringe to fill the case to the point of overflow. As stated earlier, the average measured capacity in H20 is 37.03. Interestingly, the cases varied greatly in weight but the capactiy was consistantly +/- .15gr.
I have a new batch of once fired SSA brass and I'm going to test that soon.
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That's where the internet shooting community has it's issues - a longer barrel may contribute more velocity, but it's just one part of the equation. If that barrel isn't the optimum kind of rifling, or the load used is SAMMI spec, the increase in velocity can be expected to average 30-50 fps - about 200 fps overall.
A higher quality barrel with optimized chamber, better rifling, nitrided, and using a better handload can deliver even more velocity than jut a longer barrel. It's not always better -0 there are a lot of other factors.
And improving velocity doesn't make it a better precision rifle - it's common to have to download just a tad to close up the group, max velocity isn't always the better goal. It's just a figure to brag on when numbers are getting tossed about.
As for 6.8 only working from short barrels, I haven't heard the other fanboys claiming it as much as "Ours can, too." The reality is that any cartridge can work out of a ten inch barrel - .308 has been used that way - or shot from 24" + barrels. What gets lost in the discussion is how case shape, and bullet length contribute to various combustion processes to propel the bullet.
The 6.8 case was very definitely chosen as an element to get the bullet up to speed sooner in a short barrel, the 6.5 case very definitely chosen to maximise holding a longer bullet in the same length chamber with the best flame propagation for that long bullet. And in the process of selecting powders, it was also part and parcel of the process to use a much faster powder in the 6.8 vis a vis the 6.5. That is why load for load, the 6.5 needs a longer barrel to achieve the same velocity.
After that, the bullet itself becomes a factor, the shorter 6.8 bullets lack the sectional density of the longer 6.5 bullets, and the inherent difference is that they shed power sooner and have a shorter effective range. But - they started off at least equal from a 4" shorter barrel, and the cartridge and bullet combination are not meant for long range work by the very definition of their shape. They were chosen to assimilate a lot of power quickly from a fast burning short barrel and deliver it with 50% more power than the 5.56. The 6.5 was chosen to assimilate power over a longer burn time at lower pressure to propel a longer bullet further down range where it's shape allows it to retain power longer. It doesn't necessarily have more, it just delivers it further.
Which makes the accompanying carbine, or rifle, more optimized for one or the other task. It's not that someone can't load the 6.5 with a short light round, use a fast powder, and shoot it thru a short barrel - but why bother changing so many of the ingredients of a long range recipe to make it do something the 6.8 was originally optimized to do?
It's because fanboys hang their egos on a cartridge and defend it at all costs. It's like saying "I can use a 1/2" end wrench for every bolt on a car!" because they slip an adapter onto it to fit the other. It's not the inherently elegant purpose for what it was designed to do, any more than adding a gas trap that pivots in front of the muzzle of the Winchester 94 to operate the lever action and creating a machine gun. Just because we can, doesn't mean we should.
6.8 was very definitely designed to shoot from a short barrel, and 6.5 from a longer one - which is where it set record book performances. We can try to fudge the performance to claim One Cartridge That Rules Them All, but the reality is that we are just asking a Tractor Pull Champion to put on Formula One rims and go racing on a road course. Or, fire the M4 in full auto support role without melting down - which has been proven over and over not to be a feasible course of action, just one of desperation.
If any one cartridge was better at a job than three others, we could settle on that and be done with it - but that runs counter to the imagination and marketing of man. That is why all three alternates exist for the 5.56 - to increase power, or range, but only with extreme difficulty can you do both. If so, then you have to increase recoil, which intermediates were designed to reduce compared to larger battle rifle cartridges. And that was to increase the ability for the shooter to fire more often more precisely, which anyone shooting Service Rifle will attest - the M16 holds the top ten percent of winnings precisely due to the rapid fire portion.
And that is exactly the benefit we see in combat - more bullets flying means more hits means more power on the battlefield to force the advantage to those users. We tailor our cartridges for each situation, no sense trying to get any one to do it all when the combat power of the army in the field has a large number of alternatives.
I chose the 6.8 because it has 50% more power downrange than 5.56 from a shorter barrel, which makes it a better deer rifle in broken woodland - or tactical combat, which is what the inventors were focused on. Same range, same kill zone, shorter lighter rifle. Works for me right out of the box without having to do workarounds that impede it's performance in other areas.
A higher quality barrel with optimized chamber, better rifling, nitrided, and using a better handload can deliver even more velocity than jut a longer barrel. It's not always better -0 there are a lot of other factors.
And improving velocity doesn't make it a better precision rifle - it's common to have to download just a tad to close up the group, max velocity isn't always the better goal. It's just a figure to brag on when numbers are getting tossed about.
As for 6.8 only working from short barrels, I haven't heard the other fanboys claiming it as much as "Ours can, too." The reality is that any cartridge can work out of a ten inch barrel - .308 has been used that way - or shot from 24" + barrels. What gets lost in the discussion is how case shape, and bullet length contribute to various combustion processes to propel the bullet.
The 6.8 case was very definitely chosen as an element to get the bullet up to speed sooner in a short barrel, the 6.5 case very definitely chosen to maximise holding a longer bullet in the same length chamber with the best flame propagation for that long bullet. And in the process of selecting powders, it was also part and parcel of the process to use a much faster powder in the 6.8 vis a vis the 6.5. That is why load for load, the 6.5 needs a longer barrel to achieve the same velocity.
After that, the bullet itself becomes a factor, the shorter 6.8 bullets lack the sectional density of the longer 6.5 bullets, and the inherent difference is that they shed power sooner and have a shorter effective range. But - they started off at least equal from a 4" shorter barrel, and the cartridge and bullet combination are not meant for long range work by the very definition of their shape. They were chosen to assimilate a lot of power quickly from a fast burning short barrel and deliver it with 50% more power than the 5.56. The 6.5 was chosen to assimilate power over a longer burn time at lower pressure to propel a longer bullet further down range where it's shape allows it to retain power longer. It doesn't necessarily have more, it just delivers it further.
Which makes the accompanying carbine, or rifle, more optimized for one or the other task. It's not that someone can't load the 6.5 with a short light round, use a fast powder, and shoot it thru a short barrel - but why bother changing so many of the ingredients of a long range recipe to make it do something the 6.8 was originally optimized to do?
It's because fanboys hang their egos on a cartridge and defend it at all costs. It's like saying "I can use a 1/2" end wrench for every bolt on a car!" because they slip an adapter onto it to fit the other. It's not the inherently elegant purpose for what it was designed to do, any more than adding a gas trap that pivots in front of the muzzle of the Winchester 94 to operate the lever action and creating a machine gun. Just because we can, doesn't mean we should.
6.8 was very definitely designed to shoot from a short barrel, and 6.5 from a longer one - which is where it set record book performances. We can try to fudge the performance to claim One Cartridge That Rules Them All, but the reality is that we are just asking a Tractor Pull Champion to put on Formula One rims and go racing on a road course. Or, fire the M4 in full auto support role without melting down - which has been proven over and over not to be a feasible course of action, just one of desperation.
If any one cartridge was better at a job than three others, we could settle on that and be done with it - but that runs counter to the imagination and marketing of man. That is why all three alternates exist for the 5.56 - to increase power, or range, but only with extreme difficulty can you do both. If so, then you have to increase recoil, which intermediates were designed to reduce compared to larger battle rifle cartridges. And that was to increase the ability for the shooter to fire more often more precisely, which anyone shooting Service Rifle will attest - the M16 holds the top ten percent of winnings precisely due to the rapid fire portion.
And that is exactly the benefit we see in combat - more bullets flying means more hits means more power on the battlefield to force the advantage to those users. We tailor our cartridges for each situation, no sense trying to get any one to do it all when the combat power of the army in the field has a large number of alternatives.
I chose the 6.8 because it has 50% more power downrange than 5.56 from a shorter barrel, which makes it a better deer rifle in broken woodland - or tactical combat, which is what the inventors were focused on. Same range, same kill zone, shorter lighter rifle. Works for me right out of the box without having to do workarounds that impede it's performance in other areas.
Tirod
Here's a simple question I'd like your honest opinion. You have a 175 yd. Broadside shot on a large mature mule deer buck. You have a good rest with good optics. Would you rather take the shot with a 20" ar in 5.56 shooting a 60 gr partition at 2900 fps or a 16" 6.8,spc spec2 shooting a 110 gr. Accubond at 2550? (SSA published velocity). Why?
Here's a simple question I'd like your honest opinion. You have a 175 yd. Broadside shot on a large mature mule deer buck. You have a good rest with good optics. Would you rather take the shot with a 20" ar in 5.56 shooting a 60 gr partition at 2900 fps or a 16" 6.8,spc spec2 shooting a 110 gr. Accubond at 2550? (SSA published velocity). Why?
crazysccrmd
Member
If you look at just the numbers that 5.56 load will hit at 2200fps and 647ft lbs. The 6.8 load is a little slower at 2140fps but carries way more energy at 1120 ft lbs. The 5.56 doesn't even compare in this circumstance at all.
However, hit properly with either bullet and the deer will die.
However, hit properly with either bullet and the deer will die.
crazysccrmd
Member
Yep. If you shoot a light bullet you have to increase velocity a lot to get closer to matching the energy a heavier bullet can deliver. Example, for the 60gr Partition to match the muzzle energy of the 110gr Accubond it needs to have a velocity of 3450fps. To match the energy at 175yds the 60gr bullet has to start at 3750fps.
First, I would like to have that shot at all. Where I hunt, it's extremely rare to get that kind of distance. The deer in SW MO stay in denser woodland during the rut, which is almost always our hunting season.
Sighted to a point blank range at 200m, I doubt there would be much difference 5.56 or 6.8. It should be a hit that results in the game going down in less than 100 yards movement, especially if a tad forward to hit the leg under the shoulder. Going low for the heart would be nice, but it could drop under. A hit is better than a miss.
Last year I mapped out every known kill I was aware of on the land I've hunted over 40 years, and in nearly every case it was on oak forested ridgetops being used for daylight movement. They only move in the open at night here during the rut.
It's a nice question to ask, but I have never seen it - and much of what I have experienced and read tends to make me believe that a broadside shot standing still implies the deer was tethered there for the client . . .
mr.trooper
Member
A 20" barrel is short for a hunting rifle. Many bolt gun manufacturors would call that a carbine.
May as well go whole hog unless you are planning on crawling through the brush on your belly.
May as well go whole hog unless you are planning on crawling through the brush on your belly.
Again, barrel length doesn't really contribute much to velocity. Sure, it can help, but in the case of the 6.8, a lot of shooters are seeing the same velocities out of a 16" barrel as 5.56 gets out of a 20".
It doesn't really make any difference if the ammo is loaded to deliver, and if there's no point to lugging around another pound of barrel pushing it out into the brush another 4", why bother?
Some shooters like the looks of a classic long barrel rifle is where the difference lies. That tech was predominant 50 years ago, and to look closer, it was also the era where the bullpup began to be designed, to preserve a longer barrel but shorten the rifle for closer work.
Nice goal, but ballistics has fixed a lot of the problems, plus, a reasonable view of how far we really shoot has crept into the public's apppreciation. Long range targets are the exception not the rule. It's the reason the .30-30 lever gun held on so long in American hunting history - it fit the target and range.
Intermediate cartridges shot from self loading military sporting rifles do the same job. Really a no brainer, but if someone has heard the siren song of the legendary long barreled gun, then go for it. Plenty to learn from the exercise.
It doesn't really make any difference if the ammo is loaded to deliver, and if there's no point to lugging around another pound of barrel pushing it out into the brush another 4", why bother?
Some shooters like the looks of a classic long barrel rifle is where the difference lies. That tech was predominant 50 years ago, and to look closer, it was also the era where the bullpup began to be designed, to preserve a longer barrel but shorten the rifle for closer work.
Nice goal, but ballistics has fixed a lot of the problems, plus, a reasonable view of how far we really shoot has crept into the public's apppreciation. Long range targets are the exception not the rule. It's the reason the .30-30 lever gun held on so long in American hunting history - it fit the target and range.
Intermediate cartridges shot from self loading military sporting rifles do the same job. Really a no brainer, but if someone has heard the siren song of the legendary long barreled gun, then go for it. Plenty to learn from the exercise.
Float Pilot
Member
Brother Tirod,
Did you mean to say the same energy and not velocity....???
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