Tried some 6.8 loads and factory loads today, not impressed yet

[Float Pilot]

I had a bunch of Remington small rifle bench-rest primers. So I loaded up a few and also tried some RL-10x loads at the range today.
I was not impressed.

Conditions:

Rifle: Stag 16 inch flat-top, 1 in 10 twist SPCII chamber, A2 buttstock with SSS flat spring, 6 power Leupold.
Range 100 yards
Temp: 5 to 7 degrees F, around minus 15 C
Light: Flat fading light on snow.

LOADS:

A:
Bullet: 100 grain Sierra sp, flat base
Powder: 28.5 grains, RL-10x compressed.
Primer: Remington 7 1/2 bench rest small rifle, hand seated
Brass: SSA
COL: 2.245 inch med roll crimp.
Velocity average: 2,455 fps 40 fps ES 2 inch group with last shot flyer No pressure signs

B:
Bullet: 110 grain NOSLER Accubond, boat tail
Powder: 26.6 grains, RL-10x compressed.
Primer: Remington 7 1/2 bench rest small rifle, hand seated
Brass: SSA
COL: 2.245 inch med roll crimp.
Velocity average: 2,329 fps 29 fps ES 1 inch group with last shot flyer no pressure signs



C:
Bullet: 110 grain Hornady HP flat base
Powder: 26.6 grains, RL-10x compressed.
Primer: Remington 7 1/2 bench rest small rifle, hand seated
Brass: SSA
COL: 2.228 inch med roll crimp.
Velocity average: 2,254 fps 22 fps ES 1.75 inch group with last shot flyer, no pressure signs

D:
Bullet: 110 grain Hornady OTM boat tail factory load listed as custom on the box
Powder: Factory Load
Primer: factory load
Brass: Hornady
COL: 2.245 inch
Velocity average: 2,390 fps 75 fps ES 2.75 inch group with last shot flyer
Had a couple punctured primers out of 10 rounds.

 

[R.W.Dale]

See your problem is YOUR rifle doesn't have that magic twist rate that allows an 18" 6.8 to outpreform a 22" 270win.

I too owned a 6.8spc (26" encore) and like yourself I was VERY underwhelmed with this cartridges performance. I think the problem is we both own a chrony, and the 6.8 drink is best served in ignorance. It's since became my contention that ballistically there isn't a damn thing 6.8spc does that 7.62x39mm can't do better for a lot less money.

 

[ProCarryNAustin]

Float Pilot,
I saw where you had this posted on 68forums.com as well. You might check this link for additional reloading data.
http://www.68forums.com/viewtopic.php?f=9&t=1380
There is good reloading data here using a variety of components which includes chronograph data.

As I am sure you are aware, there can be quite a bit of variation in velocity and pressures based on the components you are using. There is good data on several readily available powders and cases.


Krochus,
Ludicrous statements, insults and your single experience with this round in a rifle barrel 10" longer than normal with some unknown twist rate and chamber spec certainly does not lend credence to your argument or your credibility. Certainly not taking the "High Road" in this post. I am glad you are happy with your 7.62x39 and sure you will have lots to contribute when a thread comes up asking about the 7.62x39 and its virtues.

Daniel
Austin, Texas

 

[R.W.Dale]

Krochus,
Ludicrous statements, insults and your single experience with this round in a rifle barrel 10" longer than normal with some unknown twist rate and chamber spec certainly does not lend credence to your argument or your credibility.

The very same argument the guys over on ar15.com tries.

1 a magic twist will increase velocity by 400fps with no increase in pressure

2 but 10" of extra barrel will not add any velocity to 6.8 even though it does for every other cartridge under the sun.

3 it's impossible to look up on TC's specs using google and find my bbl had a 1 in 10 twist rate, most believe that tc used a pointy rock to cut their 6.8 chambers.

4 when someone with a chrony actually sees that this cartridge is 98% hype they get redirected over to 6.8 forums to shoot some of their radioactive 80,000psi loadings

5 merely pointing out ANY shortcoming of this cartridge is generally considered an affront to a 6.8 guy's manhood, and is little more than a personal insult.

Why do you 6.8 guy's have such a flaming case of cartridge envy? Are the 6.5g guy's that mean to ya?

 

[BornAgainBullseye]

That "B" load with the Nosler looks pretty darn nice. Id like to shoot a 1 inch group in the snow.

 

[BornAgainBullseye]

your velocity is down due the the freezing conditions. Id like to see that load in 100 degree weather

 

[Jason_G]

It's since became my contention that ballistically there isn't a damn thing 6.8spc does that 7.62x39mm can't do better for a lot less money.

I can't speak for handloads, as I am not set up to reload yet (hopefully after Christmas), but I was not very impressed by the ballistics of the 6.8 vs. 7.62x39 on paper. Further downrange the 6.8 seems to have a little more speed, but not significantly so, and when you couple the price difference of 6.8 vs. 7.62x39 into the equation, I can't see myself buying a rifle chambered in it unless I just had money to blow. On top of that, many rifles that come in 6.8 flavor also can be had in .308/7.62x51, which is heads and shoulders above in terms of ballistics and almost identical in price. That's not a flame or insult to anyone who owns a 6.8, I just don't see the allure. JMHO.

Jason

 

[rbernie]

I have several AR-15 carbines that are identical in all respects, save for being chambered in 6.8SPC or 7.62x39. I handload for both.

At 60F, I can normally drive a 123gr-125gr.3105 bullet to about 2375-2400fps out of a 16" AR barrel with MOA accuracy or better. I can gain roughly another 150fps-175fps out of a 115gr .277 bullet, which will also have a marginally better BC.

Does this difference matter? Not so much. But it is there, and it is real. I tend to prefer the 6.8SPC for a number of reasons, not the least of which is the ready availability and high reliability of 30rd magazines for the AR. The latest design C Products 7.62x39 magazines have been working for me so far, but they are fairly pricey little devils.

I've hunted with both and feel very comfortable with the performance of both. Given their reasonably complementary case capacities and such, it's not likely that one will completely blow the socks off the other. The differences are going to be driven by reloading component cost and availability (no clear winner, altho there are more lightweight .277 bullet choices) and platform (hi-cap mag availability).

 

[ProCarryNAustin]

Krochus,

There is a wonderful compilation of actual data on 68forums.com which you have for some reason ignored. Aside from pushing your own agenda, I cannot see any reason for you to disregard this information.

I was unable to find a published twist rate on the TC site for your barrel. I also do not know which chamber they are using. If you do not believe that chamber has anything to do with pressure... try firing 5.56 in a .223 chambered test barrel.

You are basing your entire argument on a single firearm you owned that was about as far out of mainstream as possible in configuration, barrel length and who knows what else.

6.8 is good for 16-18" hunting carbines. I would not even own a TC in this caliber. I would not own a 7.62x39 in a TC. If TC were to put out a 16" AR based carbine, I would entertain 6.8.

In looking at the published data on 68forums.com, I do not see any indication that anyone is developing unsafe loads. There is even a guy who posts test barrel pressures.

It is a good round for a 16" hunting carbine. Lots of folks hunting all kinds of critters and are happy with the round, the platform and the results. These are folks that are using handloads and commercial ammunition.

This was a thread about 6.8spc which you decided to crash for your own "7.62x39 solves all the worlds problems" personal agenda. My masculinity and personal pride are not tied to my rifles and your insults are counterproductive to your point.

I simply pointed a 6.8SPC reloader/poster in a 6.8SPC thread to a place that had the best reloading data I have found. It was a place he had also posted his findings.

It is unfortunate that your only apparent vehicle for discussing your point is based on personal insults and attacks. You should try to be more objective.

Daniel
Austin, Texas

 

[R.W.Dale]

There is a wonderful compilation of actual data on 68forums.com which you have for some reason ignored. Aside from pushing your own agenda, I cannot see any reason for you to disregard this information.

ignored??? I'm a member of that forum

It is unfortunate that your only apparent vehicle for discussing your point is based on personal insults and attacks. You should try to be more objective.

It's not like you have anything to offer in the way of experiance other than " go to 6.8 forum" you just cannot abide by any shortcoming of this cartridge being pointed out

My masculinity and personal pride are not tied to my rifles

your commentary shows otherwise.

You are basing your entire argument on a single firearm you owned that was about as far out of mainstream as possible in configuration, barrel length and who knows what else.

a bullet could care less what the exterior of a firearm looks like, the only thing that matters to that bullet are chamber bore, length and rifling. A 6.8 with a SAAMI chamber and a 1/10 twist is hardly out of the mainstream. Given my extra 10" of bbl I should have been beating published velocities by a wide margin.


please enlighten us with your expertise in the matter of reloading and chronographing for this round? What kind of velocities have you achieved with PRESSURE TESTED data?

 

[ProCarryNAustin]

Krochus,

For my uses, 6.8 SPC commercial ammo has it covered. My reloading experience is mostly magnum pistol cartridges which I used for IMHSA.

I pointed him to that forum because that is where the real info was.

I emailed TC to see if they would give me the twist rate and chamber spec. I have not heard back yet. Will be interesting to me to see what they have to say.

This particular cartridge was desigend for optimum efficiency out of a 16" carbine. Do you find this to not be correct?

BornAgain did have an interesting point. I did miss the temperature in the original post. That can have a substantial effect on velocity.

There have been many posts today asking about 7.62x39 and hunting... which I'm not seeing you participate in. That leads me to believe that your only purpose here is to deride and degrade.

Good luck with that.

Daniel
Austin, Texas

 

[R.W.Dale]

There have been many posts today asking about 7.62x39 and hunting... which I'm not seeing you participate in. That leads me to believe that your only purpose here is to deride and degrade.

find a topic with 7.62x39 and hunting in the title from the past few months I haven't participated in.

This particular cartridge was designed for optimum efficiency out of a 16" carbine. Do you find this to not be correct?

whilst correct, you'll still see significant velocity gains from the usage of a longer barrel in practically every centerfire rifle chambering. Are you trying to say that this doesn't hold true for 6.8


originally posted by Tim_W on ar15.com on 11/17/08

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.

I emailed TC to see if they would give me the twist rate and chamber spec. I have not heard back yet. Will be interesting to me to see what they have to say.

wow that was hard

http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=788830

For my uses, 6.8 SPC commercial ammo has it covered. My reloading experience is mostly magnum pistol cartridges which I used for IMHSA.

OH! so now it comes out that you have NO experiance reloading for and chronographing 6.8spc hand loads

 

[ProCarryNAustin]

Krochus,

Attacks aside.

I was here directing a 6.8spc reloader to a 6.8spc site with reloading info. This certainly was not any claim to expertise on my part. It was an effort to assist by point to good data. I did read over your 22 posts on 68forums. You got advice, but didn't seem to use any of it. You seemed content to use whatever components you had on hand. I would hardly call that a fair test. Maybe your rifle sucked. Unfortunate, but again adds nothing to the thread except your on personal bitterness.

What was the purpose of you posting here? You didn't add anything relevant to the original poster's observation. If my post was weak, yours was entirely unsupportive in any way or form.

Daniel
Austin, Texas

 

[R.W.Dale]

What was the purpose of you posting here? You didn't add anything relevant to the original poster's observation. If my post was weak, yours was entirely unsupportive in any way or form.

Did you read the original post?

It didn't read " I'm bowled over by 6.8sspc's performance"

no it read

Tried some 6.8 loads and factory loads today, not impressed yet

my post supports this OP's postiton and goes farther to assert that he'll NEVER be able to be content with the preformance this cartridge offers as long a sane data is used from REPUTABLE sources, especially in light of the severe overhyping people like yourself with NO experiance dish out. As to my 6.8 posts I didn't post a tenth of the data and experiments I tried with my 6.8spc, again what have you done with this cartridge? Beyond cramming some factory ammo in a magazine and blindly believing the velocity labeled on the box.

Go chronograph soem factory loads and handloads and THEN come back here with more to add to the subject than the mantra "go to 6.8 forum"

again and again you 6.8 guy's take any attempt to see beyond the hype as a personal affront to your manhood. I have not attacked you or any other poster in this thread by any stretch of the imagination. It's YOU who started your address to me with.....

Krochus,
Ludicrous statements, insults and your single experience with this round

OH! and where are those 7.62x39 threads I didn't post on?

 

[ProCarryNAustin]

Again, you added nothing to the post but your own venom.

Daniel
Austin, Texas

 

[SnakeLogan]

I'm just curious to see how a 6.8 FMJ performs in gel.

 

[R.W.Dale]

Again, you added nothing to the post but your own venom

In this one thread I've touched on bbl length, velocity, twist rate, pressure and specs for a particular barrel. Others have offered commentary on these issues as well

in 5 replies you've added "go to 6.8 forum"

no offense but that's the pot calling the kettle black. I'm coming to the conclusion that you only take the time to read things that support your view

 

[R.W.Dale]

LOADS:

A:
Bullet: 100 grain Sierra sp, flat base
Powder: 28.5 grains, RL-10x compressed.
Primer: Remington 7 1/2 bench rest small rifle, hand seated
Brass: SSA
COL: 2.245 inch med roll crimp.
Velocity average: 2,455 fps 40 fps ES 2 inch group with last shot flyer No pressure signs

according to Reloaders online data centre this load should be good for just shy of 2800fps, however the thst bbl length is unlisted. That's a pretty darn big discrepancy.

 

[cracked butt]

I'd take the data from a guy with a chronograph over the data found on a factory box or found in internet bluster forums any day.

I once considered building a hunting rifle based on the advertised ballistics as well, but as most things in advertising, the real thing rarely lives up to the hype.

 

[rbernie]

I have several AR-15 carbines that are identical in all respects, save for being chambered in 6.8SPC or 7.62x39. I handload for both.

At 60F, I can normally drive a 123gr-125gr.3105 bullet to about 2375-2400fps out of a 16" AR barrel with MOA accuracy or better. I can gain roughly another 150fps-175fps out of a 115gr .277 bullet, which will also have a marginally better BC.

I've hunted with both and feel very comfortable with the performance of both. Given their reasonably complementary case capacities and such, it's not likely that one will completely blow the socks off the other. The differences are going to be driven by reloading component cost and availability (no clear winner, altho there are more lightweight .277 bullet choices) and platform (hi-cap mag availability).

From post #8, in case any of y'all want to look past the lovefest between Krochus and ProCarryNAustin....

Just sayin'.....

 

[Bigfoot]

^^^

 

[jbech123]

Krochus,
Ludicrous statements, insults and your single experience with this round in a rifle barrel 10" longer than normal with some unknown twist rate and chamber spec certainly does not lend credence to your argument or your credibility.

I'm no ballistician and have no skin in the game, but the longer barrel is helping the 6.8's numbers(which if it can't meet published specs with a 26" bbl, well...)

 

[rbernie]

When the 6.8SPC round was introduced, Remington pushed out some pretty fantastic velocity claims for the round, just as AA did for the 6.5 Grendel. Both seemed to be in a horse race for the next-gen intermediate chambering for the AR-15 platform, and hyperbole to sell each solution as 'the best' was clearly the order of the day. The most often quoted spec from Remington had a 110gr bullet moving out at 2800fps from either a 20" or a 24" barrel (I can't recall which). Most folk who reloaded ammo took that claim with a grain of salt (given the expected case capacity of the round, it would be very hard to acheive within the standard pressure levels of the AR15 platform) but the majority of the gun-buying public took it at face value.

Compounding the perception issue, the 6.8SPC chamber specs and such were implemented in a way that caused most early commercial offerings to fail to live up to the round;'claims. In fact, many combinations of ammo-n-barrel were pretty much dogs. The 6.8SPC took a bit of a beating for failing miserably to meet the stated velocity claims. After about a year of mucking about, some of the principals in the 6.8SPC market identified the crux of the issues (abnormally early pressure spikes due to the steep chamber leade and rifling specs in common use) and set about to remediate them via altered throat specs and twist rates. These modifications to the spec and it's common commercial implementations cured the round of its early pressure spike and allowed it to achieve reasonable velocities for its case volume.

As things currently stand, the 6.8SPC is a pretty potent chambering that offers slightly higher velocities than the standard 7.62x39 round and slightly better retained downrange energy, in a package that's a LOT more AR15 friendly (due to having a lot less body taper to the cartridge).

We can get our manhood all confused with rifle rounds if we want, but I would suggest that there's little profit to be had in that exercise.

 

[Float Pilot]

Quote:
LOADS:

A:
Bullet: 100 grain Sierra sp, flat base
Powder: 28.5 grains, RL-10x compressed.
Primer: Remington 7 1/2 bench rest small rifle, hand seated
Brass: SSA
COL: 2.245 inch med roll crimp.
Velocity average: 2,455 fps 40 fps ES 2 inch group with last shot flyer No pressure signs

according to Reloaders online data centre this load should be good for just shy of 2800fps, however the thst bbl length is unlisted. That's a pretty darn big discrepancy.

Yes it should have been much faster.
AND it was the top-end loads in either the new Hornady or Speer books for RL-10x. I think it was the Hornady book that used a 16 inch DPMS carbine with a 1 in 10 twist.

And before anyone gets excited ,,,yes I have all the loading data from the 6.8Forum site as well as from Reloaders Nest.

The factory loads were 160 fps slower than advertised for a 16 inch barrel. While the lower temps may explain some of the velocity reduction, I question 160 feet of it....

And as for the suggestion to wait for a 100 degree day.... It is not likely to happen around here. Plus the winter caribou season is in the winter....in areas where it is usualy below zero...


I will experiment with a couple different primers with this powder. Then move on to some H-322 powder experiments in cold weather.

 

[R.W.Dale]

The factory loads were 160 fps slower than advertised for a 16 inch barrel. While the lower temps may explain some of the velocity reduction, I question 160 feet of it....

I might would buy 50 or 60 fps due to temp but not 350fps, especially with you using a modern propellant such as 10x