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Discussion Starter · #1 ·
This one is mostly for you 6.8r's out there. I think the issue has been settled on the superiority of the 6.5, especially at longer range, but the 6.8 is available NOW. Sometimes I tend to get a little ahead of myself as far as equipment goes, and I wonder if I really need all the extra the 6.5 offers. The two seem to be pretty close up to about 300 yards, close enought that different barrel lengths or even just different guns might make more difference than the caliber. Also, the 6.5 still isn't a laser, you need to be able to judge distance pretty accurately. After all, if the trajectory difference is even 10-12 inches at 600 yards but you misjudge by 200 yards, you'll still miss with either round. The XCR is at its best as a short, light gun, so long heavy barrels and big optics defeat the purpose-I have an LRB M-25 that weighs over 17 lbs for that, and I still don't even have the skills to use it beyond 300 (although with a 20 rd. mag I'll eventually walk 'em in!) I'm thinking of a 14.5 with permamently attached FH, and probably an Aimpoint or Eotech with magnifier. I want something that will be a decisive manstopper, and an ethical medium-sized deer round, and the 5.56 is neither. In reality, most shots that aren't at paper will probably be at coyotes. The 5.56 will do that well, but I want one gun/caliber that will do more. The 6.8 seems to do it, without being overkill(if there is such a thing!), and most guys seem to get really good accuracy, too. I already have the 7.62 conversion on order, and hopefully that will actually ship next week. I wouldn't cancel that one anyway, just because of cheap ammo, but is the 6.8 really that much better than the 7.62 within 300 yards, and if so, is the 6.5 so much better than the 6.8 as to be worth the wait(and who knows how long the wait will really be?) Just as with the SCAR/ACR issue, I'm leaning towards what is good and available vs. great and a fantasy-although I think the XCR may still be better even when the others come out! It's just a big investment, $550 for the conversion, ammo, reloading dies, bullets, etc. if I'm just going to shelve it when the 6.5 finally arrives. Thanks for the input!
 
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the one cartridge that has effectively removed the limitations of each rifle classes (assault, MBR, carbine/pdw) is the 6.8spc. it retains velocity and power very close to the 308 at range, is accurate, low recoil, more rounds per pound than the 308, more power than the x39 or 556, uses the same platform as the smaller lighter 556 and it's pressures are not excessive nor it's envelope restrictive for use in LMG's (as is the 6.5). all this out of a 16" barrel.

the neck on the 6.5 grendel is too far down the case with respect to the OAL. when it was tried in LMG links the link frequently didnt have enough hold on the case and would slide up, causing stoppages. additionally the case taper was too straight and ejection became and issue. I think that pressures may have also been stretching the brass and may have contributed to case head separations in those ejection problems. I can only assume that even tho not used in an LMG, that the inherent issues with the round with respect to combat use would make it undesireable. It's probably great for matches and hunting tho!!

additionally the 6.5 grendel is loaded to maximum pressures to achieve what it does ( which IS impressive). this would lead to increased throat erosion, and early barrel burnout, plus increased wear on the overall system. Now admittedly MOST users will never shoot thier guns enough for this to become a factor, but those same users will never shoot it to it's limitations either which negates the entire reason for buying it in the first place.

6.8 ammo is cheaper and more readily available than the 6.5 as well (i can list at least 5 manufacturers that make the 6.8 right now, the 6.5 is almost unavailable as no-one makes it)

I would also point out that the 6.8 was developed privately without government funding, in direct cooperation with end users, FROM THE GROUND UP to replace our current service cartridge. basically it's the EXACT thing that was needed considering engagement distance, rifle dimensions, ammunition weight, effect on target, accuracy, power and range.

as an example lets say that we needed a good truck for the farm. sure there are lots of choices, but lets narrow it down to 2 categories: the well built stock truck (WBST) or a lifted, modified, supercharged 38" tired, custom truck (LMST).
The custom truck does everything the stock truck does, but it requires more gas, repairs are more frequent and more expensive, parts are harder to find, it takes a ladder to get in and out of it, it's loud, it barely fits on the road. Now sure, it can crush cars and drive over 16" rocks, but how often does a farm truck need to do that. in short, it's just too much.

then there is the stock truck. It's the right size to jump in and out of all day, it gets good gas mileage, it can shoot around town easily, you can actually park it in one spot, it wont make the cows run away from you etc. etc. Now sure, it cant ford deep stream or pull stumps, but hey THATS WHY THE FARMER HAS OTHER TRUCKS AND TRACTORS. those other machines do all that stuff the custom truck does, except better and cheaper.

when you look at it the 2 rounds on paper ballistically and by the numbers, the grendel sure does look good (just like that monster truck Wink ), but when it gets right down to the REAL requirements of the rifleman and the combat troop who's engagements are usually within 150 yards and even DMR snipers only engage out to 600 with 150 being the AVERAGE, who needs to penetrate barriers regularly, who needs to carry the most amount of effective rounds for the least amount of weight, who realizes that combat accuracy is WAAAY different than benchrest accuracy (your 1/2MOA gun suddenly turns into a 5MOA system Evil ) and who just will never need that 20% extra energy at 800 yards that the 6.5 has over the 6.8, THEN you start seeing why a cheaper, simpler round (like that well built stock truck) MIGHT be a better solution.

remember, If you are engageing at 600+ yards regularly you need to be asking yourself 3 things:
1)when does the artillerly start falling?
2)Can I even see my camoflaged targets, and how do I KNOW those targets are hostile (target ID)?
3)Is a proper 300WM or 50BMG a better choice for those targets?


basically the 6.8 takes all the advantages of the 556 and the 762x39, adds them together and smooths out the wrinkles to make it better than either EVER was or could be. what I'm basically saying is that with the 6.8 you can have an assault rifle and an MBR all in one package. the XCR/6.8 might be that solution.


A friend of mine once told me that you never hear anyone bitching about how the 762x39 is lousy at what it was designed for, but you cant say the same of the 556. I'll bet you could say the same thing about the 6.8 with respect to the 6.5. Wink
 

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Eventually, no matter what caliber you get, the ammo will still be expensive. It's a dang shame.



I am buying myself one in 5.56. I am not about the caliber so much as just enjoying a day at the range- and, being the penny pincher I am, the 5.56 will work just fine for me.

the 6.8 is fun to shoot. If you want something to enjoy, that is not the mouse caliber, and you just cannnnttt waiiiiit.... buy it. But chances are by the time your 6.8 is ready to ship, the 6.5s will be, too.
 

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p.s., Steve, you are so super smart. :) I am working on your 1/8. They seem to have lost the three barrels... they're either at chroming or grinding. We're no sure. They will turn up eventually.
 

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I know this is always the worst answer, but get both. I ordered a complete 6.8 and a 6.5 kit. So I can have the stock farm truck on hand and the lift kit plus a big set of tires when I want a change. In the end I'll probably order the parts to make 2 complete guns but we'll see. You could always sell whichever you liked less.

As far as cost of ammo goes though, the Wolf 6.5 is way cheaper than any 6.8 I've seen. I don't know if it's worth a damn or if Jack was referring to reloading though.
 

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They are good at different things. so it depends on what you are after.

Try a 6.8 with a 16" tube for close in, medium contact and then assuming you get a trigger job a 6.5 with an 18" tube for DMR work.

Personally I'm skipping 6.8 at the moment. I find that .308 with a PWS muzzle brake goves me more knockdown, penetration etc. sure the rounds are heavier but i'd only need the one.

Assuming a factory match trigger, Bill Springfield or my own work makes me happy, a 6.5 kit would be nice as an intermediate rifle for spotter work olongside the Lapua. If you are after long range klnockdown and accuracy, consider an XCR-M in .260, assuming it ever gets made. Brass is cheaper, the case has good capacity and it will outshoot a .308 at range.

Plus ammo is only goin to get more expensive.
 
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here are the views of Doctor Gary K Roberts. he is probably the preeminent ballistician of our time and certainly ranks as one of the legends of ballistic testing and knowledge. I look to him first (he haunts the tactical forums) for his knowledge based upon his regular testing of loads and projectiles of all sorts for different customers and agencies.

I have also included two pictures of the 6.8 vs 308 performance. as you can see they are not that far off from each other.


Some random thoughts on the terminal performance characteristics of some of the more common projectiles in 6.8 mm:

Barnes 85 and 110 gr TSX JHP -- These all copper, lead free bullets bullets offer good expansion and penetration. They would be useful as both an LE barrier load and for hunting medium game.

Hornady 110 gr VMAX PT -- This is a great fragmenting bullet and is perfect for CQB/LE SWAT entry work; it is also a good choice for light to medium game.

Hornady 110 gr OTM (loaded by Hornady) -- This is good fragmenting bullet for military use where PT bullets like the AMAX are prohibited, as it offers similar terminal performance to the 110 gr AMAX. It has better glass performance than the 115 gr OTM.

Hornady 115 gr OTM (loaded by Remington) -- This load has dominated recent military terminal performance testing because of it’s early yaw and superb fragmentation, even at reduced impact velocities.

Remington 115 gr JSP -- Good expansion and penetration make this an excellent choice for law enforcement use through glass and other intermediate barriers, as well as into vehicles. It is also an excellent choice for hunting medium size game.

Sierra 110 gr Pro Hunter JSP -- This is a good bullet for law enforcement use through glass and other intermediate barriers and would be a great load for Highway Patrol and State Police who are working primarily around vehicles. It is also a great hunting load for medium size game.

Sierra 115 gr OTM w/cannelure -- This second generation SMK offers improved feeding reliability and much more consistent terminal performance with early yaw and ideal fragmentation. It is a good choice for military combat and non-barrier LE use.

Sierra 115 gr OTM w/o cannelure -- This first generation SMK is very accurate, but offers somewhat variable terminal performance and is not a great combat, LE, or hunting choice--it is best suited for match target shooting.

X-Treme bullets 115 gr TMJ -- This bullet offers very good soft tissue terminal performance, however, like many FMJ and OTM loads, performance through glass is not great. There have been some issues with pressure spikes using this load in undersize chambers, as well as some dimensional variances.

With the projectiles discussed above, a 1/12 twist barrel is probably the best choice!

SSA has developed two true AP loads, a 97.5 gr tungsten penetrator similar to M993/M995 and another using a hardened steel penetrator like the old .30-06 M2 AP “black-tip”.

Note: Most of the 6.8 mm bullets are continuing to upset down to at least 2100 f/s

It is very important to keep in mind that the proper 6.8 mm velocity is 2600 fps +/- 50 fps for 110-115 gr projectiles when fired from a 16" barrel. Government organizations who purchase 6.8 mm should specify in their purchase contracts a minimum acceptable velocity of 2500 fps with an objective velocity of 2600 fps for 16" barrels firing the 110-115 gr projectiles. For duty use, flash suppressed powder, crimped primer, waterproofing, and bullet cannelure should be mandatory requirements.

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Zak Smith has written the most comprehensive and accurate article on the history, genesis, and development of the 6.8 mm SPC that I have yet publicly encountered: http://demigod.org/~zak/archive/sgn_68spc.pdf Highly recommended!

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SSA 2nd generation 115 gr SMK OTM w/cannelure, 5 shot averages:

20” barrel: ave vel = 2561 fps; 10 fps extreme spread

16” barrel: ave vel = 2525 fps; 18 fps extreme spread -- lost 36 fps from 20"

12.5” barrel: ave vel = 2384 fps; 12 fps extreme spread -- lost 141 fps from 16"

10” barrel: ave vel = 2265 fps; 27 fps extreme spread -- lost 119 fps from 12.5"

7.5” barrel: ave vel = 2035 fps; 27 fps extreme spread -- lost 230 fps from 10"




heres the 6.8 115 otm (open tip match = land warfare legal)


and 308 155OTM for comparison




the 6.8 110 AMAX


and here is the highly reccomended 64grn federal TRU round in 556 (one of the best barrier and expanding projectiles tested and available for defense use)

 

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I think jack said all that needs to be said in his first post. 6.8 is a great round, and a blast to shoot. I was thinking about getting a 6.5 to go with mine but at my home range or out hunting I really won't do anything with a 6.5 that cant be done with a 6.8. I am more than confident that my 11" 6.8 will accurately drop deer and pig at the distances I shoot them with an Eotech. I am by no means a ballistics expert, I do however want to avoid having to buy reloading crap for 2 cartirdges when just one will work.
 

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You know, I like both rounds for different reasons.

The 6.8 is a great intermediate short range round.

6.5 is a beast. It shoots so flat, once its zero'ed it's almost like a cruise missle.
 

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I don't have either yet, and consider them both to be a handloading-only proposition, so I see no reason not to go with the 6.5.
 
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I will admit that the 6.5 has some fantastic ballistics and is a very attractive cartridge. If one is handloading then there wont be a whole lot of difference between the 6.8 and 6.5. heck get both if you have the means!! ;)

my arguement only applies towards a combat cartridge use, and becomes largely irrelavant if one never plans on using it outside of a range or hunting or competition.

I'm just so darn practical sometimes it's hard for me to see that less practical side of things :p
 

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There will be a huge difference. Look at the drag values for each bullet. Velocity may be similar out of the tube but the drag will determine the range capability.
 

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Discussion Starter · #14 ·
Thanks for the replies. I forgot another aspect to consider, which is muzzle blast. It has taken 34 years, but I've finally smartened up about preserving my hearing. I've done plenty of shooting, listened to loud music, ridden motorcycles, and spent lots of time around loud machinery, all without proper hearing protection most of the time. Now I'm commited to protecting what I still have, and I use hearing protection whenever practical. In a hunting situation, hearing protection isn't always practical. I have an M1A Socom that nearly fills the bill for the do-everything rifle-it needs a good mount for standard optics in addition to the forward rail, and a riser on the stock to get a good cheek weld with optics of any sort. Both of these can be fixed, but I have made the mistake of firing it or standing next to it a couple of times without hearing protection, just for one shot. I will not do it again. The muzzle break is great at reducing recoil, but it is so loud that I think the damage to my hearing is unacceptable, even for one or two shots. I'm in CA, so a suppressor is not an option. How bad is the muzzle blast on the 6.8 out of a 16 or 14.5? And does anyone know how it compares to the 6.5? And a question for Terra-you said the 6.8 wouldn't be available any sooner than the 6.5. Does that include the conversion kit? I already have the rifle in 5.56. Jack, really good info on the ballistics/developement stuff. The adaptability and logistics aspects don't matter much to me, since in reality I (hopefully) won't ever have to use it for combat. I've got too many guns already that are overly specialized, I'm trying to settle on one gun to do it all-hunting, (reasonably) affordable plinking, carbine classes, etc. If I ever have to use it for serious business, I want it to be the gun that I shoot the most and am the most proficient with, and the first and maybe only gun I will grab at a minute's notice no matter what the job.
 

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the debate of 6.5 vs 6.8 has been debated to death on different forums. they both were designed to do different things. 6.8 for combat ranges, 6.5 for longer ranges. how often will you be shooting at ranges past 300 yds? 600 yds? both are great rounds. pick one, shoot it, have fun. i have a grendel barrel on my encore. lots of fun to hit 8 inch metal plates at 350 yds. works fine on pigs at short ranges and hope to try it on deer this year. wolf ammo seems pretty cheap. will 6.8 work as well? you bet. so go try both if you can, then pick what you like best. ;D
 

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I can tell you that the muzzle blas on a 11" is pretty wild, but not much more than when the barrel was 16". it really isn't too bad though i did shoot 3 quick shots with it at a pig without hearing protection and was wishing I hadn't afterwards.
 
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There will be a huge difference. Look at the drag values for each bullet. Velocity may be similar out of the tube but the drag will determine the range capability.
I have included a PDF with grendel ballistics vs some other carts. you will notice that at 600 yards the difference between the 6.8 and 6.5 is that the 6.8 needs 1MOA more elevation correction. (115 6.8 vs the 123 6.5). I wouldnt call that a significant difference in any way. considering that most (prolly 99.9%) combat engagements are under 600 yards, there is no real advantage for choosing the 6.5 based on it's flight ballistics. The 115 OTM is at least a decent terminal performer comparitively.

there is just not enough of an advantage for me ballistically, in the 6.5 to ignore the cheaper and more available and wider accepted 6.8.

Once again, I will not deny that the 6.5 is a better long range round, but it's forte' is not combat cartridge.
 

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I wonder if the 6.5 MPC uses the 5.56/.223 case necked up? The trouble with using that case is lack of powder, in my opinion. My 6.5x284 is excellent for long range engagements BUT it isn't available in a semi-auto AR/XCR rifle yet. Of course I seldom need, have the opportunity, to shoot at over 600 meters anyway. :2cents: Too many variable at that distance for MOST of us. :2cents:
 

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I wonder if the 6.5 MPC uses the 5.56/.223 case necked up? The trouble with using that case is lack of powder, in my opinion. My 6.5x284 is excellent for long range engagements BUT it isn't available in a semi-auto AR/XCR rifle yet. Of course I seldom need, have the opportunity, to shoot at over 600 meters anyway. :2cents: Too many variable at that distance for MOST of us. :2cents:
The link I [posted above, http://www.defensereview.com/modules.php?name=News&file=article&sid=970, describes how the 6.5 MPC is made from the 5.56 cartridge case. SSK has the dies so you can make your own 6.5 MPC using 5.56 brass. One advantgae of this is that the same bolt is used for 6.5 MPC as 5.56, as well as the same mags, so only a barrel change is needed. I wonder if soemone could rebore an XCR 5.56 heavy barrel to 6.5 MPC?

I sent SSK an email to see what they thought of reboring an XCR 5.56 heavy barrel to 6.5 MPC. I suspect it won't work because the shoulder is set back on the 6.5 MPC.
 

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There will be a huge difference. Look at the drag values for each bullet. Velocity may be similar out of the tube but the drag will determine the range capability.
I have included a PDF with grendel ballistics vs some other carts. you will notice that at 600 yards the difference between the 6.8 and 6.5 is that the 6.8 needs 1MOA more elevation correction. (115 6.8 vs the 123 6.5). I wouldnt call that a significant difference in any way. considering that most (prolly 99.9%) combat engagements are under 600 yards, there is no real advantage for choosing the 6.5 based on it's flight ballistics. The 115 OTM is at least a decent terminal performer comparitively.

there is just not enough of an advantage for me ballistically, in the 6.5 to ignore the cheaper and more available and wider accepted 6.8.

Once again, I will not deny that the 6.5 is a better long range round, but it's forte' is not combat cartridge.
Granted 6.8 and 6.5 are very similar at carbine range, and on paper both on superior to 5.56NATO. But it is much more interesting when you consider 6.5 vs. 7.62NATO and the potential as a DMR/sniper round. Looking at the numbers, 6.5 is capable of replacing both 5.56 and 7.62 NATO rounds, and that is something you cannot say about 6.8.

Being that in reality neither 6.5 or 6.8 has been adopted the argument that 6.8 is cheaper and therefore preferable is very valid. But if/when one of these rounds IS adopted, that will no longer apply. And truly adoption of one of these cartridges is what will end up "deciding" which is "better".
 
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