6.8 spc going to go the way of the dodo bird?

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[ARCHIVED THREAD] - 6.8 spc going to go the way of the dodo bird? (Page 1 of 2)

Posted: 11/16/2008 1:30:49 PM EDT

what say you? I have heard people go so far as to say that this is already a dead issue with the military and there is no longer a consideration for this cartridge. I like what the cartridge is capable of and I eventually want an LMT mrp upper in this chambering, but I dont want to pay 3984582 dollars per box of ammo.

Posted: 11/16/2008 2:07:15 PM EDT

[#1]

I wouldn't worry about ammo scarcity. I can readily buy .44/77 brass, and reload with readily avbl components. No one's chambered a rifle for .44/77 in maybe 110 years.

Posted: 11/16/2008 2:25:26 PM EDT

[#2]

If anything the 6.8 SPC has gained a lot of momentum in the past year. More and more manufacturers are offering parts and ammo selection is even more varied.

6.8 will never be as ubiquitous as 5.56 because the military is not going to wholesale switch calibers.

Posted: 11/16/2008 2:31:56 PM EDT

[#3]

Quoted:
what say you? I have heard people go so far as to say that this is already a dead issue with the military and there is no longer a consideration for this cartridge. I like what the cartridge is capable of and I eventually want an LMT mrp upper in this chambering, but I dont want to pay 3984582 dollars per box of ammo.

Remington screwed the pooch on the 6.8. Thankfully; Hornaday, SSA and BH have stepped up to the plate. I have two LMT CQB MRP among other 6.8 weponss, both with 6.8 barrels. My 6.8 LMTs have shot even the SSA 115gr MIL/LE ammo with no visual signs of over pressure. When you say general .mil adoption. no. That will not change until the M16/M4 weapon system is completely replaced and I don't mean DI versus Piston.

Posted: 11/16/2008 3:09:42 PM EDT

[#4]

If anything after languishing in obscurity for 3 or so years the 6.8 is now well on it's way to becoming mainstream. The 6.5 on the other hand has Bill Alexander doing everthhing possible to kill off his creation and help out 6.8spc sales

The military angle didn't mean squat as that project was all but dead from the git go.

Posted: 11/16/2008 3:16:21 PM EDT

[#5]

Quoted:The 6.5 on the other hand has Bill Alexander doing everthhing possible to kill off his creation and help out 6.8spc sales

Yes, including licensing it to Robarms for the XCR. LaRue seems like he is going to make uppers in 6.5G. How about Sabre Defence offering uppers in 6.5G? Wolf offering ammo...

Seems like maybe you are overstating your bias.

Posted: 11/16/2008 3:51:05 PM EDT

[#6]

Seems like maybe you are overstating your bias.

My bias is for neither one of these cartridges, in fact I've owned and been seriously disappointed by 6.8spc even in a 26" encore barrel

I found it amusing when I saw that Model1Sales booth at the Tulsa gunshow had generic "6.5" uppers for sale. Further questioning revealed that they were in fact chambered for Grendel but they couldn't call a duck a duck due to strict licensing. In the end only being avalibe in mega $$$ platforms well spell the demise of 6.5grendel, soon to be the .41ae of the AR15 world

Posted: 11/16/2008 3:55:30 PM EDT

[#7]

I think it has the potential to be a good niche round. Not wildly popular but gaining enough of a fan base to stick around for a long time.

My third upper is probably going to be a 6.8SPC.

Posted: 11/16/2008 4:35:12 PM EDT

[#8]

Quoted:In the end only being avalibe in mega $$$ platforms well spell the demise of 6.5grendel...

I guess we all have different concepts of "mega $$$". I think $320 for a stainless barrel and bolt is pretty reasonable.

Any way, back on topic....

Posted: 11/16/2008 4:43:17 PM EDT

[#9]

Quoted:

Quoted:The 6.5 on the other hand has Bill Alexander doing everthhing possible to kill off his creation and help out 6.8spc sales

Yes, including licensing it to Robarms for the XCR. LaRue seems like he is going to make uppers in 6.5G. How about Sabre Defence offering uppers in 6.5G? Wolf offering ammo...

Seems like maybe you are overstating your bias.

Has something changed recently? The last I looked RobArms was producing an unlicensed copy of 6.5 Grendel.

Posted: 11/16/2008 4:59:54 PM EDT

[#10]

I was in the gym and met a marine who just got back from Iraq. He said that the rank and file are hoping for the 6.8 SPC due to the increased range of engagement. I don't know what the decision makers think, but the average marine wants it.

Posted: 11/16/2008 5:21:18 PM EDT

[#11]

Quoted:Has something changed recently? The last I looked RobArms was producing an unlicensed copy of 6.5 Grendel.

That's what I get for reading the internet. I don't know is the answer....I thought it was licensed.

Posted: 11/16/2008 5:49:48 PM EDT

[#12]

Quoted:
I was in the gym and met a marine who just got back from Iraq. He said that the rank and file are hoping for the 6.8 SPC due to the increased range of engagement. I don't know what the decision makers think, but the average marine wants it.

The "average" Marine has no frickin idea what 6.8 is.

Posted: 11/16/2008 6:25:19 PM EDT

[#13]

6.8 spc going to go the way of the dodo bird?

I hope so. The 6.5 pisses all over the 6.8 ballistically.

Posted: 11/16/2008 6:40:26 PM EDT

[#14]

With every major AR manufacturer except for Colt making 6.8 uppers and more and more ammo companies and rounds coming out for this cartridge I doubt it will go away anytime soon. Contrary to belief of some this round is accurate to 600+ yds (farthest I've had the opportunity to shoot it was 600).

Posted: 11/16/2008 6:43:59 PM EDT

[#15]

3crowns––Not sure what you mean by "pisses" or "ballistically", but to date, 6.8SPC has met USG end-user ballistic requirements in every test conducted, including JSWB-IPT, USMC, and CTTSO/TSWG, while 6.5G has not. Do you have other facts to the contrary?

Posted: 11/16/2008 6:49:32 PM EDT

[#16]

I wish I had 5 dodo birds

Posted: 11/16/2008 7:04:33 PM EDT

[#17]

If Cabela's has 6.8 brass in there retail store(they do), it's not a do do bird.

6.8 is all over the place.

6.8 is COOL

Posted: 11/16/2008 7:27:32 PM EDT

[#18]

Quoted:
[., in fact I've owned and been seriously disappointed by 6.8spc even in a 26" encore barrel

.

Why would you use an intermediate cartridge intended for 12"-16" barrels in a 26" barrel?

In an 18" barrel I've been very happy with the results, the minimal gains in going to a 20" barrel just are not worth it to me, I could never see going with something as long as 26".

Posted: 11/16/2008 7:28:59 PM EDT

[#19]

If it is a dodo bird, (and most signs suggest otherwise) then it should still last me about a lifetime with all the brass I have laying around.

Posted: 11/16/2008 7:33:36 PM EDT

[#20]

Quoted:
6.8 spc going to go the way of the dodo bird?

I hope so. The 6.5 pisses all over the 6.8 ballistically.

More BARFcom wisdom.

Posted: 11/16/2008 7:36:21 PM EDT

[#21]

Why would you use an intermediate cartridge intended for 12"-16" barrels in a 26" barrel?

Why not, theses smaller cased rounds receive a free boost in velocity from more bbl just like any other

I wanted a really efficient cartridge to shoot medium bore 110 to 130grn bullets out to 300m accurately from a nice heavy and stable platform avalible as a factory bbl. Even in the encore's 26"bbl factory ammo and published load data for 6.8 failed to meet factory specifications. Kinda like the old burger king commercials "where's the beef"

Ironically my current Stevens 200 7.62x39mm bench gun with it's 26"bbl blows published velocities out of the water. It hits 2800fps easily with 110grn bullets within published load data. Plus it's so much more accurate than the encore was it's pathetic

Posted: 11/16/2008 8:06:04 PM EDT

[#22]

Quoted:

Why would you use an intermediate cartridge intended for 12"-16" barrels in a 26" barrel?

.........Kinda like the old burger king commercials "where's the beef"

that was Wendy's.......

I figue I have enough 6.8 brass to last for a while.......don't see it going away anytime soon.....

Posted: 11/16/2008 10:08:20 PM EDT

[#23]

Flyboy, I don't know what the issues are regarding military adoption of the 6.8 (does anyone for sure?) but there is no doubt that it is becoming more and more popular every day. Far from the endangered species list with all the manufacturers now producing it. As for the ammo, it has actually become cheaper in the past year. I just paid 12.99/box for 90 gr. HP loads from the best maker of 6.8 ammo. My advice––buy that LMT and don't look back!

Posted: 11/17/2008 2:26:14 AM EDT

[#24]

Quoted:

Even in the encore's 26"bbl factory ammo and published load data for 6.8 failed to meet factory specifications.

Ironically my current Stevens 200 7.62x39mm bench gun with it's 26"bbl blows published velocities out of the water.

If you bought an off the rack T/C 6.8 SPC barrel it is a 10 twist, with an "unknown" chamber.

On the other hand - your comparison piece.

Your 7.62x39 bolt gun is a 15 twist, .308 groove diameter Shilen.

Apples and oranges, full truckloads of them.

Posted: 11/17/2008 3:07:30 AM EDT

[#25]

Quoted:

Why would you use an intermediate cartridge intended for 12"-16" barrels in a 26" barrel?

Why not, theses smaller cased rounds receive a free boost in velocity from more bbl just like any other

I wanted a really efficient cartridge to shoot medium bore 110 to 130grn bullets out to 300m accurately from a nice heavy and stable platform avalible as a factory bbl. Even in the encore's 26"bbl factory ammo and published load data for 6.8 failed to meet factory specifications. Kinda like the old burger king commercials "where's the beef"

Ironically my current Stevens 200 7.62x39mm bench gun with it's 26"bbl blows published velocities out of the water. It hits 2800fps easily with 110grn bullets within published load data. Plus it's so much more accurate than the encore was it's pathetic

how does that compare to an 18" 3 groove 1/12 barrel shooting a 110 gr bullet at 3200fps like the 6.8 will do?

Posted: 11/17/2008 6:24:21 AM EDT

[#26]

how does that compare to an 18" 3 groove 1/12 barrel shooting a 110 gr bullet at 3200fps like the 6.8 will do?

Kinda brings a certain George Straight song to mind.

I would love to see what the chamber pressures on this load are since 270 winchester has to work pretty hard to achieve those speeds in a 22" rifle bbl with right at twice the case capacity and a 65,000psi pressure rating. No magic twist rate is going to allow 6.8 to outrun 270 in a shorter bbl without dramatically ramping up pressures. I've noticed you AR guys are perfectly willing to disregard what are obviously insane chamber pressure when you get fixated on an outlandish velocity claim.

You 6.8 guys really need to set your cartridge inferiority complex aside and take a hard look at some of the insane loads you fellas use.

Posted: 11/17/2008 7:37:08 AM EDT

[#27]

Quoted:
6.8 spc going to go the way of the dodo bird?

I hope so. The 6.5 pisses all over the 6.8 ballistically.

Yeah, with rounds you have to single load. They are 99.5% the same out to 600 yards, which is the basic point of combat rifles (really 300 yards).

Posted: 11/17/2008 7:51:11 AM EDT

[#28]

Quoted:

how does that compare to an 18" 3 groove 1/12 barrel shooting a 110 gr bullet at 3200fps like the 6.8 will do?

Kinda brings a certain George Straight song to mind.

I would love to see what the chamber pressures on this load are since 270 winchester has to work pretty hard to achieve those speeds in a 22" rifle bbl with right at twice the case capacity and a 65,000psi pressure rating. No magic twist rate is going to allow 6.8 to outrun 270 in a shorter bbl without dramatically ramping up pressures. I've noticed you AR guys are perfectly willing to disregard what are obviously insane chamber pressure when you get fixated on an outlandish velocity claim.

You 6.8 guys really need to set your cartridge inferiority complex aside and take a hard look at some of the insane loads you fellas use.

You know those are verified/chronographed numbers, right?

Posted: 11/17/2008 7:55:09 AM EDT

[#29]

Tag

Posted: 11/17/2008 8:18:47 AM EDT

[#30]

Quoted:
Tag

I love it when he does that.

Posted: 11/17/2008 9:08:28 AM EDT

[#31]

Quoted:

Why would you use an intermediate cartridge intended for 12"-16" barrels in a 26" barrel?

Why not, theses smaller cased rounds receive a free boost in velocity from more bbl just like any other

I wanted a really efficient cartridge to shoot medium bore 110 to 130grn bullets out to 300m accurately from a nice heavy and stable platform avalible as a factory bbl. Even in the encore's 26"bbl factory ammo and published load data for 6.8 failed to meet factory specifications. Kinda like the old burger king commercials "where's the beef"

Ironically my current Stevens 200 7.62x39mm bench gun with it's 26"bbl blows published velocities out of the water. It hits 2800fps easily with 110grn bullets within published load data. Plus it's so much more accurate than the encore was it's pathetic

I really wouldn't doubt that the bullet slowed down using that barrel length. The 6.8 was designed to have its powder completely consumed in the first 8-10" of the barrel. Using the longer barrel with its gases expanded completely early in the barrel, it stands to reason that barrel friction is starting to overcome gas pressure after a certain length.

Posted: 11/17/2008 9:27:18 AM EDT

[#32]

I don't think military adoption is a good barometer of the success of a round.

There are lots of popular cartridges out there that have never been military.

I think 6.8 is going to stay around. It's a good round and support is growing.

6.5 is not going away either. I think the fact that there are several makers making guns in "not 6.5" says a lot about the demand from the customers.

The 6.5 vs 6.8 reminds me a lot of my uncles debating the merits of the .280 Remington vs .270 Winchester. Reams of data and much raised voices. The deer aren't any deader from one or the other.

Posted: 11/17/2008 9:54:55 AM EDT

[#33]

Quoted:
Tag

what does this mean. forgive me for being a newb

ETA: nevermind I figured it out.

Posted: 11/17/2008 10:44:34 AM EDT

[#34]

Quoted:
I don't think military adoption is a good barometer of the success of a round.

There are lots of popular cartridges out there that have never been military.

I think 6.8 is going to stay around. It's a good round and support is growing.

6.5 is not going away either. I think the fact that there are several makers making guns in "not 6.5" says a lot about the demand from the customers.

The 6.5 vs 6.8 reminds me a lot of my uncles debating the merits of the .280 Remington vs .270 Winchester. Reams of data and much raised voices. The deer aren't any deader from one or the other.

I think mil adoption may be considered ONE but certainly not THE yard stick.

40 S&W has seen widespread adoption in the LEO community, if the 6.8 takes that path and there are some indicators it will, well thats one thing to be said.

I do not much care which gets adopted by who, but people with more free time on their hands then I do love to engage in such debates, says something I think.

Each has their own merits on which each stands strong.

Posted: 11/17/2008 11:47:13 AM EDT

[#35]

Quoted:

Quoted:

Tag

I love it when he does that.

No fun now that you're here.

Posted: 11/17/2008 12:15:24 PM EDT

[#36]

I think it's fantastic that this exact topic pops up so often on ARFCOM. It bespeaks a rising groundswell of interest in alternate calibers for the AR, which is only a good thing.

Development of the 6.8 ecosystem (cartridges, bullets, powders, barrels, etc) is proceeding quite rapidly and we will see excellent availability of optimized ammo and barrels in 2009. CMT and LMT both make factory bolts for 6.8, and the LMT bolts are the same design as their enhanced 5.56 bolts. Noveske has transitioned their 6.8 product line to SPCII chambers and 1:12 twist 4-groove poly barrels, which will allow the use of very hot handloads and the SSA combat loads (how about a 110gr Accubond coming out of an 18" barrel at close to 2800fps with no pressure signs?). Stag is apparently going to all 1:11 twist SPCII barrels, WOA has this same config available, and on and on.

The 6.5 crowd is also growing the stable of licensed manufacturers, with Charles Daly Defense being a very likely producer in 2009. Alexander Arms is working through its bolt shortage, so production and availability should be much better in 2009. And you can't get much better than the Lapua brass AA uses in is factory ammo. Wolf continues to supply cheap plinking ammo, and the 120gr MTP load is actually quite decent; a steal at less than $11 per box of 20. Right now, you may wait a bit longer for 6.5G components, but if you want to shoot those high BC bullets are moderate velocities, it'll be worth it.

Bottom line is you will absolutely spank any given 5.56 mag-length load with either 6.5 or 6.8. Too cool.

Posted: 11/17/2008 1:10:51 PM EDT

[#37]

vmpglenn––good post!

Posted: 11/17/2008 1:59:27 PM EDT

[#38]

I really wouldn't doubt that the bullet slowed down using that barrel length. The 6.8 was designed to have its powder completely consumed in the first 8-10" of the barrel. Using the longer barrel with its gases expanded completely early in the barrel, it stands to reason that barrel friction is starting to overcome gas pressure after a certain length.

Umm even 22lr will gain velocity in a 26" tube over a 16"

how does that compare to an 18" 3 groove 1/12 barrel shooting a 110 gr bullet at 3200fps like the 6.8 will do?

Ok I'll bite what kind of powder and how much are you using in this kaboom waiting to happen?

Posted: 11/17/2008 2:42:39 PM EDT

[#39]

but w ill the 22lr gain in a 26 vs 20? no

Posted: 11/17/2008 3:50:34 PM EDT

[#40]

Ah but we have people arguing that 6.8 spc won't gain velocity when going from 16" to 26". This is abject silliness. Then again so is 6.8 having higher velocities than .270 winchester. With roughly half the case volume and a shorter barrel the pressures would have to be OVER 70,000 PSI!!!!

Posted: 11/17/2008 3:50:42 PM EDT

[#41]

Quoted:

Quoted:
I was in the gym and met a marine who just got back from Iraq. He said that the rank and file are hoping for the 6.8 SPC due to the increased range of engagement. I don't know what the decision makers think, but the average marine wants it.

The "average" Marine has no frickin idea what 6.8 is.

The internet never ceases to amaze me...

One hour after a poster tells of a Marine getting back from iraq telling about other Marines who
love the 6.8....

An actual Marine IN IRAQ tells his observations...

Really amazing...

Thank you for watching over my family Marine...God Bless & Watch Over You..

My nephew is in his last couple of weeks of BRC...and chomping at the bit to get over there with you..

Gotta try and find him some PMAGs for Christmas

Posted: 11/17/2008 5:07:42 PM EDT

[#42]

7mm08 will make a 100 grain bullet go 3327fps out of a 24" barrel. This cartridge has significantly more case capacity than 6.8spc which is claimed to go almost as fast with a 10% HEAVIER bullet. Yes I realize they are different bore diameters .007 isn't much difference though. There simply aren't that many .277 calibers out there to compare to. And the ones that are out there are at least double the size of the spc.

Posted: 11/17/2008 5:33:01 PM EDT

[#43]

Quoted:

Ah but we have people arguing that 6.8 spc won't gain velocity when going from 16" to 26". This is abject silliness. Then again so is 6.8 having higher velocities than .270 winchester. With roughly half the case volume and a shorter barrel the pressures would have to be OVER 70,000 PSI!!!!

A couple things...Have you read this report???

http://www.ar15.com/forums/topic.html?b=3&f=121&t=369145&page=9

You will see actual pressures from barrel stress/pressure equipment for different loads.

When in your mind do you see the great 22LR starting to slow down??? Is there a barrel length in which is does slow down or even stop or does it increase velocity until it reaches hyper/warp speed and disappears???? Please show data!!!!!!!!

You have my data with the link...Show us your data pages...Please

<Inflammatory comment removed - Z>

Posted: 11/17/2008 5:41:05 PM EDT

[#44]

Quoted:
7mm08 will make a 100 grain bullet go 3327fps out of a 24" barrel. This cartridge has significantly more case capacity than 6.8spc which is claimed to go almost as fast with a 10% HEAVIER bullet.

What would that same 7-08 do with, say a 13 or 14 twist barrel, instead of the 9 its wearing from the factory and matching the throat, barrel groove and land width/depth dimensions for that of a specific projectile?

There's a lot of "optimizing" that can be done on damn near anything, although at some point you're narrowing the potential scope/audience every time you "fix" something.

Posted: 11/17/2008 6:03:31 PM EDT

[#45]

Will the 6.8 go the way of the DODO? Most likely it will.

The Dodo became extinct in 1662, about 346 years ago give or take a year.

I would venture a guess that in 346 years, or by 2354, the 6.8 will not be a viable caliber in comparison to the Plasma Phase Rifle, or the Illudium PU-36 Explosive Space Modulator, not to mention the various Phaser products offered by the giant UN World Government owned and operated small arms manufacturer DPMS.

By the way, everyone on this forum will be extinct by then also.

In the meantime, the 6.8 is supported by almost "EVERY" AR manufacturer except for Colt as mentioned above. Ammo is supported by several sources, as well as magazines. The cartridge continues to develop with several manufacturers like Noveske, AR15performance, WOA, Stag, DPMS moving towards the slower twists the original designers wanted with the improved SPC II and DMR chambers. Other companies like RRA have projects underway studying future 6.8 offerings. LWRC, Barrett, Robinson Arms, MSAR, and Ruger also have 6.8 products. There are more offerings coming and may show up at SHOT this year.

Hey the 6.5 has a few companies offering rifles for it too, so it's probably staying around for its fans for a while also.

If you want either caliber, go buy it before you're extinct!!

Posted: 11/17/2008 6:36:33 PM EDT

[#46]

Someone should mention that the vast variety of cartridges did nothing to blunt bolt action sales.

There's room for many rounds out there in the AR platform too.

I don't think there is such a thing as dead as a dodo for cartridges anyway. There will always be someone loading and shooting it. For heaven's sake, there are companies making new Spencer carbines and .56-56 rimfire ammo! That gun and round were unobtanium ten years ago.

Posted: 11/17/2008 6:44:59 PM EDT

[#47]

Quoted:

Quoted:
7mm08 will make a 100 grain bullet go 3327fps out of a 24" barrel. This cartridge has significantly more case capacity than 6.8spc which is claimed to go almost as fast with a 10% HEAVIER bullet.

What would that same 7-08 do with, say a 13 or 14 twist barrel, instead of the 9 its wearing from the factory and matching the throat, barrel groove and land width/depth dimensions for that of a specific projectile?

There's a lot of "optimizing" that can be done on damn near anything, although at some point you're narrowing the potential scope/audience every time you "fix" something.

So if we put your magical 1:12 twist barrel on a .270 Weatherby magnum would it get 8000fps with a 110 grain bullet? Of course not. According to you guys barrel LENGTH won't increase the velocity of 6.8spc but the twist rate will!! I still want to know how much of what powder is making those 110 grain bullets go 3200 fps and how far from the gun was the chronograph?

Posted: 11/17/2008 6:45:54 PM EDT

[#48]

Quoted:
Will the 6.8 go the way of the DODO? Most likely it will.

The Dodo became extinct in 1662, about 346 years ago give or take a year.

I would venture a guess that in 346 years, or by 2354, the 6.8 will not be a viable caliber in comparison to the Plasma Phase Rifle, or the Illudium PU-36 Explosive Space Modulator, not to mention the various Phaser products offered by the giant UN World Government owned and operated small arms manufacturer DPMS.

By the way, everyone on this forum will be extinct by then also.

If you want either caliber, go buy it before you're extinct!!

Sir,

If I ever meet you, I am buying you a beer, that post, priceless.

Ah screw it, Im buying you a team membership for that post, it is just that damn good.

ETA: Ok I bought you a membership, that post has me laughing here in the library, that was classic! Log out then log in to activate the membership , you earned it with that. "go buy it before you're extinct!!" THAT IS FRIGGIN CLASSIC.

Posted: 11/17/2008 6:53:33 PM EDT

[#49]

Quoted:

Quoted:
Ah but we have people arguing that 6.8 spc won't gain velocity when going from 16" to 26". This is abject silliness. Then again so is 6.8 having higher velocities than .270 winchester. With roughly half the case volume and a shorter barrel the pressures would have to be OVER 70,000 PSI!!!!

A couple things...Have you read this report???

http://www.ar15.com/forums/topic.html?b=3&f=121&t=369145&page=9

You will see actual pressures from barrel stress/pressure equipment for different loads.

When in your mind do you see the great 22LR starting to slow down??? Is there a barrel length in which is does slow down or even stop or does it increase velocity until it reaches hyper/warp speed and disappears???? Please show data!!!!!!!!

You have my data with the link...Show us your data pages...Please

<Inflammatory comment removed - Z>

I have no idea how long of a barrel it would take for a .22lr to slow down. However I do know that 22lr shot out of a 24 inch barrel is FASTER than when shot out of an 18 inch barrel. 6.8spc produces more exhaust gas at a higher pressure so it's safe to assume the same is true for it.

As for your link I didn't see anything on there about a 110 grain bullet going 3200fps so how exactly does that apply to the argument?

Posted: 11/17/2008 7:40:39 PM EDT

[#50]

For standard .22LR ammo max velocity is reached around 16". The only way to accurately test this is to cut a barrel down inch by inch which has been done in various tests. Many barrels will shoot faster then other barrels even ones shorter. The reason longer barrel were used was for longer sight radius and not maximum velocity.

The 6.8 even though it was developed and does very well at SBR lengths will continue to gain velocity well past even 40". When you consider a max need pressure to initially fully engage the rifling of about 3800 PSI for a typical jackets bullet whihc is much higher then and to keep it moving once fulling engaged you can use that number along with the bore volume and pressure to extrapolate the barrel length. The barrel length would actually be longer but without known the exact fiction of a particular barrel and with the various specs out there over stating seems the best course. But its still ridiculously long which makes the whole thing rather academic at best. Obviously the load used will have an effect as well.

Butt for a typical load of say
110 Hrdy OTM
32 gr H335

You are looking at 35"-36" before it meets the point of no vel gain but again this is using a pressure number that is significantly higher then what is actually happening. The real number may be 10-20" longer easily. The main point was to show that with any barrel most can get a bullet slowing down from even the relatively small case of the 6.8 is not a concern. But once you do get above 20" and certainly 26" the gain per inch is significantly reduced and continues to do so. IMHO 20" is the longest barrel that would make sense from a general overall performance stand point for the 6.8 IMHO.

[ARCHIVED THREAD] - 6.8 spc going to go the way of the dodo bird? (Page 1 of 2)

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