6.8 SPC vs. 7.62x39?
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Zak Smith
Member
JohnKSa,
Your point is definitely correct in 7.62x39 vs. 6.8SPC.
However, it does not always hold true. For example:
Code:
_Bullet_ _BC_ _MV_ 0 200 400 600 800 1000 1200 | YARDS
300WM 155 Scenar 0.508 3300 > -0.00 0.00 3.27 7.42 12.33 18.13 25.01 | drop (moa)
300WM 210gr VLD 0.640 2900 > -0.00 0.00 4.20 9.29 15.13 21.82 29.48 | drop (moa)
300WM 155 Scenar 0.508 3300 > 0.00 1.64 6.84 16.15 30.26 50.00 76.41 | wind (inches)
300WM 210gr VLD 0.640 2900 > 0.00 1.53 6.35 14.91 27.71 45.34 68.49 | wind (inches)The 155gr load is 4.5MOA flatter at 1200 yards, but has 8" more wind.
regards
Zak
Ok, Zak, educate me--I'm trying to draw some general conclusions and I've jumped the track somewhere.
Here is my (mis?)conception.
Assuming muzzle velocities in the same general neighborhood, flatter trajectory is a result of shorter TOF which is a result of better BC.
Better BC and shorter TOF results in less wind drift.
Therefore flatter trajectory = less wind drift.
Where did I go wrong?
Here is my (mis?)conception.
Assuming muzzle velocities in the same general neighborhood, flatter trajectory is a result of shorter TOF which is a result of better BC.
Better BC and shorter TOF results in less wind drift.
Therefore flatter trajectory = less wind drift.
Where did I go wrong?
Zak Smith
Member
JohnKSa,
Let me briefly diverge. There are several levels at which we can "model" these ballistics. 1 We can measure data in the field and record the salient features. 2 We can use the best numerical physics models developed over the last 150 years for predicting trajectory of symmetric projectiles. 3. We can use our intuition. (There are more of course, but we're already talking about these 3.)
The first is really "no model", just a reporting of what actually happened. The second and third are predictive models. The former (numeric physics models) have proven so accurate that the field has been dead since the 80's. It's done all that it can be asked to do, which is predict the actual POI within an extremely small margin of error. The last, our intuition, is a kind of model, but it relies on a small set of general rules to obtain vague answers.
If we assume the work of all numeric ballisticians in the last century was not for nothing, then that example of a faster bullet (also with shorter flight time!) having more wind drift is a fact. It's not really a hypothesis, but more a conclusion of a proven predictive system. (Since I haven't actually shot those two loads at 1200 yards and instrumented everything!)
Here are some intuitive rules:
If we keep the BC's the same, the faster of the two bullets will have less wind drift and drop.
If we keep the velocities the same, the higher-BC of the two bullets will have less wind drift and drop.
If both aspects are increased vs. the "control" bullet, the result will again be even less wind drift and drop.
However, in this case, one bullet has a higher BC but a lower MV than the other. This plays the general rules listed above against each other.
The aspect that enables the non-intuitive behavior of the 155/3300 vs. 210/2900 case is that the drag in any direction is modulated by the BC. Even though the 155 Scenar takes 0.10 sec less long to travel to 1200 yards, the wind affects it more per time because its BC is significantly less than the 210VLD's BC.
Hope this helps. The best way to get a good understanding of this stuff is to play with a quality ballistic computer for a long time.
-z
Let me briefly diverge. There are several levels at which we can "model" these ballistics. 1 We can measure data in the field and record the salient features. 2 We can use the best numerical physics models developed over the last 150 years for predicting trajectory of symmetric projectiles. 3. We can use our intuition. (There are more of course, but we're already talking about these 3.)
The first is really "no model", just a reporting of what actually happened. The second and third are predictive models. The former (numeric physics models) have proven so accurate that the field has been dead since the 80's. It's done all that it can be asked to do, which is predict the actual POI within an extremely small margin of error. The last, our intuition, is a kind of model, but it relies on a small set of general rules to obtain vague answers.
If we assume the work of all numeric ballisticians in the last century was not for nothing, then that example of a faster bullet (also with shorter flight time!) having more wind drift is a fact. It's not really a hypothesis, but more a conclusion of a proven predictive system. (Since I haven't actually shot those two loads at 1200 yards and instrumented everything!)
Here are some intuitive rules:
If we keep the BC's the same, the faster of the two bullets will have less wind drift and drop.
If we keep the velocities the same, the higher-BC of the two bullets will have less wind drift and drop.
If both aspects are increased vs. the "control" bullet, the result will again be even less wind drift and drop.
However, in this case, one bullet has a higher BC but a lower MV than the other. This plays the general rules listed above against each other.
The aspect that enables the non-intuitive behavior of the 155/3300 vs. 210/2900 case is that the drag in any direction is modulated by the BC. Even though the 155 Scenar takes 0.10 sec less long to travel to 1200 yards, the wind affects it more per time because its BC is significantly less than the 210VLD's BC.
Hope this helps. The best way to get a good understanding of this stuff is to play with a quality ballistic computer for a long time.
-z
money
last time i went to shop for a rifle, and i must say it's been awhile. an ar-15 was quite a chunk of money. and nobody can tell me a 5.56 round can hit as hard up close as a 7.62x39. so the introduction of this 6.8 is no good news to me. i might agree that it outperforms the 39. but not enough for me to go out and spend a grand plus on a good ar-15 and then convert it. i gave 200 bucks for my sks. i am not an awesome shooter, but it performs pretty decent. show me a 6.8 on the market for even 300 bucks. and we will talk about the really slight edge in performance it provides.
last time i went to shop for a rifle, and i must say it's been awhile. an ar-15 was quite a chunk of money. and nobody can tell me a 5.56 round can hit as hard up close as a 7.62x39. so the introduction of this 6.8 is no good news to me. i might agree that it outperforms the 39. but not enough for me to go out and spend a grand plus on a good ar-15 and then convert it. i gave 200 bucks for my sks. i am not an awesome shooter, but it performs pretty decent. show me a 6.8 on the market for even 300 bucks. and we will talk about the really slight edge in performance it provides.
R.W.Dale
Member
holy dead thread batman
Cohibra45
Member
Welcome to the 'High Road'!!!
Way to go with your first post........finding a 2005 thread and stirring the pot on anything 6.x vs 'name it'....
BTW, I'm sure your $199 SKS, which is $100 more than I paid for mine back in the day will shoot just fine. Don't worry yourself about any new calibers or the rifles that shoot them.
You can kill deer very well with it I'm sure.
Seriously, the SKS is a fine rifle for what it was intentioned to be. It even works well as a fairly close in deer/black bear rifle with the right ammo. It eats up the cheap steel cased stuff and is an all around fun gun.
It is not, and can never be, brought up in the same breath as an AR however...two totally different animals. That is why there is at least a $500 difference between your SKS and any baseline AR. The AR can easily be brought up to an accurate Long Range shooter (see 1000yd range Camp Perry) whereas your SKS will be stretching it to shoot 300yds.
It's not that your bullet choice isn't accurate.....we're talking rifles here. The 6.x vs 'name your round' has been discussed and argued, fought and died for here and on other sites about long enough. Suffice it to say that for practical purposes, your rifle and cartridge (for the price you paid) should suit you just fine. Others like myself have sold off their SKSs and moved up in quality with the AR platform.
Just don't come on here and expect to start another rant........although I'm some here will surely oblige you.
Way to go with your first post........finding a 2005 thread and stirring the pot on anything 6.x vs 'name it'....
BTW, I'm sure your $199 SKS, which is $100 more than I paid for mine back in the day will shoot just fine. Don't worry yourself about any new calibers or the rifles that shoot them.
You can kill deer very well with it I'm sure.Seriously, the SKS is a fine rifle for what it was intentioned to be. It even works well as a fairly close in deer/black bear rifle with the right ammo. It eats up the cheap steel cased stuff and is an all around fun gun.
It is not, and can never be, brought up in the same breath as an AR however...two totally different animals. That is why there is at least a $500 difference between your SKS and any baseline AR. The AR can easily be brought up to an accurate Long Range shooter (see 1000yd range Camp Perry) whereas your SKS will be stretching it to shoot 300yds.
It's not that your bullet choice isn't accurate.....we're talking rifles here. The 6.x vs 'name your round' has been discussed and argued, fought and died for here and on other sites about long enough. Suffice it to say that for practical purposes, your rifle and cartridge (for the price you paid) should suit you just fine. Others like myself have sold off their SKSs and moved up in quality with the AR platform.
Just don't come on here and expect to start another rant........although I'm some here will surely oblige you.
Lucky
Member
Zak Smith
Member
The 2009 Book of the AK-47 is out now, with my full article in it (the abstract Lucky posted above). If you look at the directions I suggest for getting best use of, and improving, the 7.62x39, they do not relate directly to 6.8's strengths.
-z
-z
As I've opined before on this subject, the 6.8SPC practically duplicates the terminal behavior of the .276 Pedersen and .280 British rounds, the former being developed in the early 30's, the latter being developed after WWII based on lessons learned during that war. The Pedersen round was really on to something and the British developed their pratically duplicated version afterwards realizing their .280 retained the best traits of what they wanted in a combat round.
As both "ideal" rounds both were trounced by Americans, the .276 nemesis being McArthur and the .280 nemesis being the U.S. Military's stubborness in adopting the 7.62X51 (a .30-06 in tighter fitting clothes).
So as the bull in the china cabinet, we are again witnessing the stubborness of the American Military to make questionable choices. Of course, we'll never know the political tangled webs involved in any governmental decision-making.
I say though, that if the 6.8 and related rifles were as prevelant in the market as the 7.62X39 and AK variant rifles were, I'd of been all over it over the 7.62X39.
But I think what we all really missed out on was the reduced-sized .276 Pedersen Garands, that gun would've been a hoot.
As both "ideal" rounds both were trounced by Americans, the .276 nemesis being McArthur and the .280 nemesis being the U.S. Military's stubborness in adopting the 7.62X51 (a .30-06 in tighter fitting clothes).
So as the bull in the china cabinet, we are again witnessing the stubborness of the American Military to make questionable choices. Of course, we'll never know the political tangled webs involved in any governmental decision-making.
I say though, that if the 6.8 and related rifles were as prevelant in the market as the 7.62X39 and AK variant rifles were, I'd of been all over it over the 7.62X39.
But I think what we all really missed out on was the reduced-sized .276 Pedersen Garands, that gun would've been a hoot.
HorseSoldier
Member
+1 what amprecon said.
6.8
Having owned all of the calibers in question, I'll add my observations. 7.62x39 ballistics are very similar. there is little comparison in stopping power between 7.62 comlboc to 7.62 nato as the nato round from a good rifle will hit accurately and kill at 800 yards. I have an lwrc gas piston gun in 6.8. It is very reliable, though I would not put it up there with ak's or g3's. The principal piston gun out there being used in the field was the hk 416 which seemed to do just swell. the 6.8 with the hornady v-max out of my gun will shoot 1 inch groups using a millett 1-4 dot scope. I believe the groups could possibly get tighter using a conventional scope. I never was a fan of .223. The special forces invented 6.8 to give a carbine weight rifle more reach and hitting power. Reports from afghanistan and Iraq confirm the 6.8 does the job. I still have 308 rifles I like. but i have no reservations on the 6.8
Having owned all of the calibers in question, I'll add my observations. 7.62x39 ballistics are very similar. there is little comparison in stopping power between 7.62 comlboc to 7.62 nato as the nato round from a good rifle will hit accurately and kill at 800 yards. I have an lwrc gas piston gun in 6.8. It is very reliable, though I would not put it up there with ak's or g3's. The principal piston gun out there being used in the field was the hk 416 which seemed to do just swell. the 6.8 with the hornady v-max out of my gun will shoot 1 inch groups using a millett 1-4 dot scope. I believe the groups could possibly get tighter using a conventional scope. I never was a fan of .223. The special forces invented 6.8 to give a carbine weight rifle more reach and hitting power. Reports from afghanistan and Iraq confirm the 6.8 does the job. I still have 308 rifles I like. but i have no reservations on the 6.8
Interesting Opinions
I found the information regarding the attributes of various primarily military ammunition very interesting indeed. I came to this forum to find out what I could about the 6.8 SPC and have decided that based on what I have read so far my next weapon purchase will in fact be a Robinson XCR cambered in 6.8 SPC.
I am not a range shooter and neither do I any sort of competitive shooting but I am a deer hunter and have bagged deer with a multitude of weapons including primitive weapons but most have been taken with the venerable win. 30-30. I saw a couple of derogatory comments about the 30-30 and found myself questioning this derision. If the 30-30 is so bad then why have so many deer been taken with the various versions of an excellent "brush gun?" I grew up in the Catskill Mountains in upstate N.Y. where the need of a long range weapon is not as much of an issue.
Ballistic data shows the 6.8 SPC to be a "better mousetrap." I am one of those "paranoid" about the coming days of "societal breakdown" when defending one's family and property will become a personal matter. Having a weapon that can serve multiple needs is paramount. Having taken a couple of deer with an AK I would say that overall performance favors the 30-30.
Now to the argument that "on paper" the 6.8 SPC is superior to both the 5.56 and the 7.62x39 and that the only way to really know is with real time real life uses to see if it will kill a human as well as either of the those two that are now in common use i would have to say that I read another article about a "road test" using the 6.8 on a 150 lb. mule deer. A one shot kill. That tells me all I need to know.
From my standpoint, I love the 7.62 NATO but at my advancing age the recoil has become a bit much. I think a .243 is another good deer rifle but aren't we really discussing military weapons? If I had my choice of the 3 calibers being discussed here the 6.8 SPC wins hands down.
I found the information regarding the attributes of various primarily military ammunition very interesting indeed. I came to this forum to find out what I could about the 6.8 SPC and have decided that based on what I have read so far my next weapon purchase will in fact be a Robinson XCR cambered in 6.8 SPC.
I am not a range shooter and neither do I any sort of competitive shooting but I am a deer hunter and have bagged deer with a multitude of weapons including primitive weapons but most have been taken with the venerable win. 30-30. I saw a couple of derogatory comments about the 30-30 and found myself questioning this derision. If the 30-30 is so bad then why have so many deer been taken with the various versions of an excellent "brush gun?" I grew up in the Catskill Mountains in upstate N.Y. where the need of a long range weapon is not as much of an issue.
Ballistic data shows the 6.8 SPC to be a "better mousetrap." I am one of those "paranoid" about the coming days of "societal breakdown" when defending one's family and property will become a personal matter. Having a weapon that can serve multiple needs is paramount. Having taken a couple of deer with an AK I would say that overall performance favors the 30-30.
Now to the argument that "on paper" the 6.8 SPC is superior to both the 5.56 and the 7.62x39 and that the only way to really know is with real time real life uses to see if it will kill a human as well as either of the those two that are now in common use i would have to say that I read another article about a "road test" using the 6.8 on a 150 lb. mule deer. A one shot kill. That tells me all I need to know.
From my standpoint, I love the 7.62 NATO but at my advancing age the recoil has become a bit much. I think a .243 is another good deer rifle but aren't we really discussing military weapons? If I had my choice of the 3 calibers being discussed here the 6.8 SPC wins hands down.
Interesting Opinions
I found the information regarding the attributes of various primarily military ammunition very interesting indeed. I came to this forum to find out what I could about the 6.8 SPC and have decided that based on what I have read so far my next weapon purchase will in fact be a Robinson XCR cambered in 6.8 SPC.
I am not a range shooter and neither do I any sort of competitive shooting but I am a deer hunter and have bagged deer with a multitude of weapons including primitive weapons but most have been taken with the venerable win. 30-30. I saw a couple of derogatory comments about the 30-30 and found myself questioning this derision. If the 30-30 is so bad then why have so many deer been taken with the various versions of an excellent "brush gun?" I grew up in the Catskill Mountains in upstate N.Y. where the need of a long range weapon is not as much of an issue.
Ballistic data shows the 6.8 SPC to be a "better mousetrap." I am one of those "paranoid" about the coming days of "societal breakdown" when defending one's family and property will become a personal matter. Having a weapon that can serve multiple needs is paramount. Having taken a couple of deer with an AK I would say that overall performance favors the 30-30.
Now to the argument that "on paper" the 6.8 SPC is superior to both the 5.56 and the 7.62x39 and that the only way to really know is with real time real life uses to see if it will kill a human as well as either of the those two that are now in common use i would have to say that I read another article about a "road test" using the 6.8 on a 150 lb. mule deer. A one shot kill. That tells me all I need to know.
From my standpoint, I love the 7.62 NATO but at my advancing age the recoil has become a bit much. I think a .243 is another good deer rifle but aren't we really discussing military weapons? If I had my choice of the 3 calibers being discussed here the 6.8 SPC wins hands down.
I found the information regarding the attributes of various primarily military ammunition very interesting indeed. I came to this forum to find out what I could about the 6.8 SPC and have decided that based on what I have read so far my next weapon purchase will in fact be a Robinson XCR cambered in 6.8 SPC.
I am not a range shooter and neither do I any sort of competitive shooting but I am a deer hunter and have bagged deer with a multitude of weapons including primitive weapons but most have been taken with the venerable win. 30-30. I saw a couple of derogatory comments about the 30-30 and found myself questioning this derision. If the 30-30 is so bad then why have so many deer been taken with the various versions of an excellent "brush gun?" I grew up in the Catskill Mountains in upstate N.Y. where the need of a long range weapon is not as much of an issue.
Ballistic data shows the 6.8 SPC to be a "better mousetrap." I am one of those "paranoid" about the coming days of "societal breakdown" when defending one's family and property will become a personal matter. Having a weapon that can serve multiple needs is paramount. Having taken a couple of deer with an AK I would say that overall performance favors the 30-30.
Now to the argument that "on paper" the 6.8 SPC is superior to both the 5.56 and the 7.62x39 and that the only way to really know is with real time real life uses to see if it will kill a human as well as either of the those two that are now in common use i would have to say that I read another article about a "road test" using the 6.8 on a 150 lb. mule deer. A one shot kill. That tells me all I need to know.
From my standpoint, I love the 7.62 NATO but at my advancing age the recoil has become a bit much. I think a .243 is another good deer rifle but aren't we really discussing military weapons? If I had my choice of the 3 calibers being discussed here the 6.8 SPC wins hands down.
A very detailed review of the 6.8SPC
http://demigodllc.com/articles/6.8-...y-development-hornady-stag-arms-carbine/?p=11
http://demigodllc.com/articles/6.8-...y-development-hornady-stag-arms-carbine/?p=11
If you are preparing for societal breakdown, selecting a rifle firing a very niche and hard to get cartridge seems like a recipe to be left without ammo and with a very expensive club. I think Napoleon once said "Amateurs talk of tactics, professionals talk of logistics."
Maverick223
Member
Well at least this recent resurrection wasn't 4 yrs. old. Dave, Welcome to THR.
those with more specialized needs would almost certainly be better served by the 6.8........
i have seen the round and a mini ruger at a store claiming to be the 6.8spc.
as a stand alone weapon i dont know that it makes any more or less sense (except for cost) than near-by calibers.
if the round can be put through an m4-ish platform without having to buy two rifles and just some interchangable rifle components at lower cost than two rifles - a 5.56 doing what it does best and the 6.8spc with its set of ballistic advantges (or legal deer hunting issues...-so i have read- in some states) then it seems like a neat offering in the cartridge dept. and not such a specialized round after all. if what i have read is true. i am not sure. hopefully it isnt all a lie.
i have seen the round and a mini ruger at a store claiming to be the 6.8spc.
as a stand alone weapon i dont know that it makes any more or less sense (except for cost) than near-by calibers.
if the round can be put through an m4-ish platform without having to buy two rifles and just some interchangable rifle components at lower cost than two rifles - a 5.56 doing what it does best and the 6.8spc with its set of ballistic advantges (or legal deer hunting issues...-so i have read- in some states) then it seems like a neat offering in the cartridge dept. and not such a specialized round after all. if what i have read is true. i am not sure. hopefully it isnt all a lie.
The trajectory of the 6.8 is very similar to the trajectory of the .223 and .308. The 6.8 is said to have at least 40% more energy on target than the .223 with almost half the recoil of the .308. We won't compare the trajectory of the 7.62X39 to any of those listed above, but it is deadly and accurate enough within 100yds without much sight adjustment.
longdayjake
Member
Rise!!! RISE!!! IT'S ALIVE!!!!
Welcome back ancient thread.
Kind of funny to see all the misinformation that was tossed out a few years ago.
Welcome back ancient thread.
Kind of funny to see all the misinformation that was tossed out a few years ago.
Omaha-BeenGlockin
Member
Well---at least the newbies are using the search function.
R.W.Dale
Member
Yet 5 years later where are we?
Still with two or three diffrent chambers, underperforming SAAMI spec guns and loads and a select few factory load offerings with no cheaper plinking ammo.
Has anything changed?
Still with two or three diffrent chambers, underperforming SAAMI spec guns and loads and a select few factory load offerings with no cheaper plinking ammo.
Has anything changed?
That's almost as many chamber options as .223
. At least Barnes and Hornady have taken notice with new offerings (Hornady 120 gr SST just announced). Everything else is just rumor for now. The only thing that can be certain is plinking rounds are a pipe dream. The 6.8 will never be a mag dump cartridge.Looking over the last five years, the 6.8 is a huge success. It's the #1 alternative caliber for the AR15.
It takes millions of rounds a year to achieve cheap plinker status, those who look to any non military caliber for that - other than .22 - are being intensely naive or worse. But, then again, some people thought Bushmaster or FN would get them new designs for the price of the 45 year old AR.
The 6.8 is doing great with those who demand terminal results. It now has dozens of suppliers of barrels, uppers, ammo, and finished guns. All the Tier One makers offer it. Hunters buy it because it makes the AR "legal" to hunt. It offers enough power to take down game, with reputedly fewer losses than 5.56. Apparently, there aren't that many feral French hunting canines to be controlled, hogs and deer are more likely.
So far the only other competitor would be the newly released .300 BLK, a Whisper copy. It can use standard bolts and magazines, but there really isn't much savings, if any. It's promised to have cheap plinker ammo made for it, and the supersonic ballistics are promised to be just like the 7.62-39. Which makes it a .30-30, at best.
Talk about reinventing the wheel.
I don't expect 25c a round, it's not a military surplus caliber, either.
It takes millions of rounds a year to achieve cheap plinker status, those who look to any non military caliber for that - other than .22 - are being intensely naive or worse. But, then again, some people thought Bushmaster or FN would get them new designs for the price of the 45 year old AR.
The 6.8 is doing great with those who demand terminal results. It now has dozens of suppliers of barrels, uppers, ammo, and finished guns. All the Tier One makers offer it. Hunters buy it because it makes the AR "legal" to hunt. It offers enough power to take down game, with reputedly fewer losses than 5.56. Apparently, there aren't that many feral French hunting canines to be controlled, hogs and deer are more likely.
So far the only other competitor would be the newly released .300 BLK, a Whisper copy. It can use standard bolts and magazines, but there really isn't much savings, if any. It's promised to have cheap plinker ammo made for it, and the supersonic ballistics are promised to be just like the 7.62-39. Which makes it a .30-30, at best.
Talk about reinventing the wheel.
I don't expect 25c a round, it's not a military surplus caliber, either.
- Status
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