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mike_the_wino
09-22-2012, 11:14 AM
I have two carbines (1 M4 clone w/ irons and a Spikes upper w/ BAR and an Aimpoint), an A3 clone (irons), a bench rest betty (decent glass, bipod, White Oak SS fluted upper) and one AR15 lower receiver. Empty. The poor thing just stares at me. All alone on the top shelf with magazines and spare parts. At some point I would like an AR10 but that isn't high the list right now. But I got a crazy thought about getting all wood for this just for something different.

Any idears?

connorr931
09-22-2012, 11:43 AM
AR308

k1dude
09-22-2012, 11:55 AM
1 - 6.5 Grendel over the AR10 and the 6.8. Same ballistics as the .308, but fits in the AR-15. Better ballistics than the 6.8 SPC II.

2 - .50 Beowolf or .458 Socom.

mike_the_wino
09-22-2012, 12:54 PM
AR308
Can't build on an AR15 lower. :(

Plus my brother has two all ready. Why buy when you can inherit. :D

Cereal though, I like the 6.5 Grendel! Totally overlooked this option. Expensive as heck (Precision) but looks like it would be a solid hog gun.

FMJBT
09-22-2012, 1:31 PM
A MK 12 Mod 0 clone.


















In 6.5 Grendel :D

ar15barrels
09-22-2012, 9:44 PM
Build a precision bolt rifle and learn what real precision is all about...

chicoredneck
09-22-2012, 9:50 PM
Decide what you want it for and go from there. Hunting, range work, safe art, long range and/or target? Once you figure that out you can start shopping for an upper that fits your needs.

wash
09-22-2012, 9:58 PM
Dedicated .22lr for cheap training and plinking. No drop in bolt, a real .22 barrel with no gas port.

Ideally a pencil barrel ~carbine with pinned on front sight, pinned A2 flash hider, carbine length MOE handguard, Mil-spec buffer tube, MOE stock or similar, rear sight to suit and a real mag release button.

tradecraft
09-22-2012, 10:01 PM
Sell it and start on an 80% build for an AR pistol.

mike_the_wino
09-22-2012, 10:40 PM
Dedicated .22lr for cheap training and plinking.
Dammit wash, I had just decided on the 6.5 Grendel because of K1dude's suggestion made sense for a nice hog gun. Hell, I was done to just 18" or 20" barrel and now you throw this out. Hell, that's a whole 'nother build. But I like where you are going with that. :D

@ar15barrels, planning on a 700 at some point but not now.

wash
09-22-2012, 11:21 PM
Yeah, 525 rounds of .22lr or 20 rounds of Wolf 6.5 Grendle...

As for .308 ballistics in an AR15, BS.

If you look at 6.8 SPC next to 6.5 Grendle, you'll see that 6.8 SPC has the advantage in velocity and energy out to 250+ yards and the hunting bullets are fantastic.

If you think most of your hunting shots are 300 yards or less, 6.8 SPC will perform better than Grendle.

If you aren't concerned with clean kills, 6.8 SPC can be impressively accurate out past 500 yards.

Grendle can be accurate out further but because the muzzle velocity is so low, there is lots of drop.

sunborder
09-22-2012, 11:33 PM
Wash, I have to ask, since I see your sig pictures so often, WTF is up with that lower pic?

Oh, and +1 on the .22lr upper. I was thinking the same thing.

You might want to wait for the pink Magpul furniture that they just announced. Have somebody paint a my little pony or hello kitty on the side...

You know, "pink bronies"...men who love my little pony and will shoot you if you try to pony bash them...

(it must be late at night, I am conflating the pink pistols with bronies and pink magpul furniture...)

mike_the_wino
09-22-2012, 11:59 PM
If you aren't concerned with clean kills, 6.8 SPC can be impressively accurate out past 500 yards.
But, but, but...I found this 'un (http://www.jprifles.com/1.2.2_JP15.php) in 6.5 Grendel and 18" barrel. Ain't she perty?

And I am considering clean kills a paramount priority. I don't want to be "that guy".

Back to square one....*sigh*

Oh, and I hope you "tacticool" voters are just being smartasses because that was the wrong answer. Who the feck needs all that carp on their riffle?

sunborder
09-23-2012, 12:18 AM
Who the feck needs all that carp on their riffle?

Well, I suppose you could paint a fish on that pink rifle if you wanted to...

k1dude
09-23-2012, 2:03 AM
wash, the 6.8 SPC II's superior ballistics out to 250 yards are those wildcatters that are pushing the psi to the limits. One of these days someone is going to get hurt or killed. The orgininal 6.8 SPC can't hold a candle the the Grendel.

The 6.5 Grendel chamber pressures are well within safe ranges and still hold their own against the 6.8. Everything the 6.8 can do, the Grendel can do better. The ONLY situation a 6.8 performs better with normal loads is in an SBR or pistol. The 6.8 performs very well out of a short barrel.

And why limit yourself to 300 yards on a rifle? Why would you take 300 yards over a rifle that has excellent ballistics out to 800 yards? What if you decide to try for Antelope in Nevada and you have to take a 600 yard shot? Oops, too bad I bought a 6.8 instead of a 6.5.

And SAAMI just accepted the Grendel. Expect to see much more ammo and guns from all the manufacturers.

wash
09-23-2012, 10:58 AM
Good luck with a clean kill using a Grendle past about 350 yards.

Choosing a maximum range for a rifle is about accuracy, bullet expansion and energy. If your rifle isn't accurate, your range is going to be short, if your bullet does not retain enough energy to expand, your going to take closer shots that will expand the bullet. If your bullet does not have enough energy to penetrate to the vitals and smash through some bone, you're going to take closer shots that have enough energy.

In 6.8 SPC with a decent marksman, a good rifle is accurate enough to take a 300 yard shot fairly easily, the bullets will expand at that range and they carry enough energy to penetrate and create quick kills.

A .308 really isn't a 500 yard hunting rifle and 6.5 Grendle isn't a .308 despite what some people think.

As for wildcatting, you've got your story mixed up.

When Remington submitted 6.8 SPC to SAAMI, they screwed up the throat or something.

The revised 6.8 SPC II chamber (much the same as the original 6.8 SPC before Remington screwed it up) uses ammo loaded with the same dies but can use faster powders because the initial pressure spike is nowhere near as high. That translates to higher velocity with lower chamber pressures.

Hand loaders can get impressively high velocity out of 6.8 SPC but they are not being any more aggressive than people hand loading 6.5 Grendle. The thing that sucks is that factory 6.8 SPC ammo is all weak so it won't blow up rifles with the old chamber.

One more thing, those ballistics numbers of the 6.5 Grendle that an old 6.8 SPC can't hold a candle to, the Grendle was using a 24" barrel.

I don't know why but Grendle owners think 6.8 SPC owners are stuck in the past and are very selective about the details they pay attention to.

Dead*Reckoned
09-23-2012, 11:07 AM
.510 dtc, or. 416. Or get a beltfed .22 upper.

wash
09-23-2012, 11:12 AM
Oh, that JP, it must be nice but did you see the 6.5 Grendle safety warning?

For Sunboarder, that's King Khan sticking his naked butt in Lindsey Lohan's face while she was violating her parole in France. Some things are so dumb they deserve to be commemorated and it makes me smile. But my screen saver is a picture of Siamese twins so I like weird things.

wash
09-23-2012, 11:26 AM
I found a new one:

http://img.thesun.co.uk/multimedia/archive/01574/Brittany-Hensel-62_1574435a.jpg

And my screen saver:

http://xenophilius.files.wordpress.com/2008/04/abigailbritanny02.jpg

They seem to be well adjusted and happy, I think that is awesome.

k1dude
09-23-2012, 11:47 AM
Good luck with a clean kill using a Grendle past about 350 yards.

Choosing a maximum range for a rifle is about accuracy, bullet expansion and energy. If your rifle isn't accurate, your range is going to be short, if your bullet does not retain enough energy to expand, your going to take closer shots that will expand the bullet. If your bullet does not have enough energy to penetrate to the vitals and smash through some bone, you're going to take closer shots that have enough energy.

In 6.8 SPC with a decent marksman, a good rifle is accurate enough to take a 300 yard shot fairly easily, the bullets will expand at that range and they carry enough energy to penetrate and create quick kills.

A .308 really isn't a 500 yard hunting rifle and 6.5 Grendle isn't a .308 despite what some people think.

As for wildcatting, you've got your story mixed up.

When Remington submitted 6.8 SPC to SAAMI, they screwed up the throat or something.

The revised 6.8 SPC II chamber (much the same as the original 6.8 SPC before Remington screwed it up) uses ammo loaded with the same dies but can use faster powders because the initial pressure spike is nowhere near as high. That translates to higher velocity with lower chamber pressures.

Hand loaders can get impressively high velocity out of 6.8 SPC but they are not being any more aggressive than people hand loading 6.5 Grendle. The thing that sucks is that factory 6.8 SPC ammo is all weak so it won't blow up rifles with the old chamber.

One more thing, those ballistics numbers of the 6.5 Grendle that an old 6.8 SPC can't hold a candle to, the Grendle was using a 24" barrel.

I don't know why but Grendle owners think 6.8 SPC owners are stuck in the past and are very selective about the details they pay attention to.

There is so much disinformation in your post that I barely know where to start.

I suggest you do a little reading both online and in print. The 6.5 Grendel already has a long proven history taking medium and large game at very long ranges. The penetration and expansion has been exemplary.

Not on par with .308? I suggest you do some simple searches. It not only matches .308, but surpasses it.

As far as wildcatters, once again, do some reading. Most of those eye-opening ballistics are pushing the 55,000 psi limit way beyond to 60,000 to 62,000 psi. There was no "screw up" with the original SPC adopted by Saami. Wildcatters just found they could push the chamber pressures further with a simple geometry change. But now they are pushing the boundaries beyond all safety ranges. Have you noticed Saami hasn't adopted the SPC II? Or that no one is willing to publish simple ballistics tables even though it's been out for many years? Gee, I wonder why.

And if you want an apples to apples comparison, Grendel wildcatters are getting performance that blows away anything the 6.8 SPC II crowd can put out. But I didn't even bring that up because it's inherently unsafe. Once again, ANYTHING the 6.8 can do, the 6.5 can do better - except short barrels.

And no, the superior 6.5 numbers over the original 6.8 was using 14.5" to 24" barrels. Once again, do your research. The 6.5 beat the 6.8 using every barrel size from 14.5" to 24". The 6.8 wins from 7.5" to 14.5".

Another benefit of the 6.8 over the 6.5 is barrier penetration. So if you were a soldier in some town in Iraq, the 6.8 would be your choice for the shorter ranges and barrier performance. But if you were in the Hindu Kush, you would want the legs of the 6.5. The 6.8 also has a slight theoretical advantage in reliability of feeding out of the magazine since the shoulder is less steep.

In past years, the only reason to choose the 6.8 over the 6.5 was availability of commercial ammo. The 6.8 SPC (not SPC II) was Saami and the 6.5 wasn't. If you wanted 6.5, you needed to be a handloader or pay the big bucks from AA. At least until Wolf and Hornady began to supply 6.5 Grendel ammo. You can get Wolf and Hornady 6.5 commercial ammo from many suppliers. Now that the 6.5 Grendel is Saami, expect much more widespread availability.

You seriously need to do some reading before posting so much FUD. I suggest trying to post your "knowledge" over at 65Grendel.com and let them rip you a new one with real numbers.

Dead*Reckoned
09-23-2012, 12:26 PM
Not on par with .308? I suggest you do some simple searches. It not only matches .308, but surpasses it.


huh?

wash
09-23-2012, 12:50 PM
More 6.5 Grendle SAAMI crack being smoked.

6.8 SPC became popular after the chamber was fixed. I don't have time for a history lesson but the SAAMI chamber was screwed up. That is why the ammo companies had such a hard time making ammo that matched the velocity that the cartridge "promised". Look it up.

What you can take from that is if the gun works a SAAMI spec is nice but it doesn't really sell guns. The time for Alexander Arms to get a SAAMI spec was years ago and they are doing it now to try to sell more rifles. .264 LBC was starting to eat their lunch because their stuff was overpriced. With a SAAMI spec at least the rifles will say 6.5 Grendle and they can say inventor of the 6.5 Grendle. It's a business move, trying to make the caliber more popular after they figured out they couldn't sustain their monopoly. I doubt it will work.

Discounting the falsehoods in your post, what you have are two guns that are effective 300 yard hunting rifles when you use an appropriate bullet. If they are built well enough they are accurate out much farther although the bullet drop can be big. Inside of 300 yards, 6.8 SPC packs more punch. For a military application where wounding counts, Grendle is more effective for really long shots.

I don't think I'll be zipping people at 700 yards very often so 6.8 SPC does everything I will use it for better.

k1dude
09-23-2012, 2:02 PM
huh?

Typical ballistics:

.308

Dist.....Vel........Ene.

0.........2,789....1,727
100......2,526....1,418
500......1,630....590
1,000...1,000....222

6.5 Grendel

0.........2,620....1,875
100......2,460....1,653
500......1,875....961
1,000...1,300....462

Or per Hornady's charts- they don't go to 1,000 yards:

.308

0.........3,165....2,446
100......2,830....1,956
500......1,708....712

6.5 Grendel

0.........2,590....1,832
100......2,420....1,599
500......1,805....889

wash
09-23-2012, 2:11 PM
How's your Grendle with a slower lighter bullet getting more muzzle energy?

Math fail.

k1dude
09-23-2012, 2:14 PM
More 6.5 Grendle SAAMI crack being smoked.

6.8 SPC became popular after the chamber was fixed. I don't have time for a history lesson but the SAAMI chamber was screwed up. That is why the ammo companies had such a hard time making ammo that matched the velocity that the cartridge "promised". Look it up.

What you can take from that is if the gun works a SAAMI spec is nice but it doesn't really sell guns. The time for Alexander Arms to get a SAAMI spec was years ago and they are doing it now to try to sell more rifles. .264 LBC was starting to eat their lunch because their stuff was overpriced. With a SAAMI spec at least the rifles will say 6.5 Grendle and they can say inventor of the 6.5 Grendle. It's a business move, trying to make the caliber more popular after they figured out they couldn't sustain their monopoly. I doubt it will work.

Discounting the falsehoods in your post, what you have are two guns that are effective 300 yard hunting rifles when you use an appropriate bullet. If they are built well enough they are accurate out much farther although the bullet drop can be big. Inside of 300 yards, 6.8 SPC packs more punch. For a military application where wounding counts, Grendle is more effective for really long shots.

I don't think I'll be zipping people at 700 yards very often so 6.8 SPC does everything I will use it for better.

Blah blah blah. It sounds like you have a personal problem with Bill Alexander and not the cartridge itself. Your post rambles on about the failings of how Bill handled the marketing of the cartridge instead of the pros and cons of the actual cartridge.

I happen to agree with you about the marketing of the cartridge and how Bill handled it all. But I don't hold that against the cartridge.

As I already pointed out, the 6.8 would be superior for troops in urban fighting like in Iraq. But for Afghanistan, the 6.5 would be superior. And that means for most people who are hunting, the 6.5 would be superior for California. I have promoted the 6.8 as a hunting round if you live in heavily wooded terrain back east where short ranges and heavy underbrush are the norm. But for the west with our wide open country, the 6.5 is better. And it holds it's own with shorter ranges too.

If you think a pig is going to notice the difference between a 6.8 or a 6.5 at 300 yards, you're delusional.

Once again, why choose a 300 yard cartridge over an 800 yard cartridge?

k1dude
09-23-2012, 2:15 PM
How's your Grendle with a slower lighter bullet getting more muzzle energy?

Math fail.

110gr .308 vs 123gr 6.5.

duh.

wash
09-23-2012, 2:51 PM
Who shoots 110 grain .308?

That is a really bizarre comparison which is par for the course with Grendle fans.

Typical .308 would be more like NATO 7.62*51, 150 grain ball or maybe a 168 grain match king.

While Alexander arms did screw up the marketing, that's no excuse for the Grendle but fan boys wear it like a badge.

There is no way in hell that 6.5 Grendle is a reasonable 800 yard hunting cartridge. Hitting paper is a different story but 6.8 SPC can hit paper at 800 yards too.

If that's not enough, magazines. Argue that one.

sunborder
09-23-2012, 4:47 PM
110gr .308 vs 123gr 6.5.

Um, I have no beef in this, since I own neither, but seriously? a 110 grain .308 bullet should be pushing 3300fps, even with published loads. And what bullet is that? 110 grain hornady round nose? Or a spitzer type bullet?

I see where you got that 110 grain Hornady data. That's the 110 grain TAP-FPD data for .308. The .308 above (which I assume is some sort of 150ish grain ball load) is WAY under the ballistics available for TAP in 155 grain or 168 grain, which are more normal loads. BTW, those two hornady loads blow away the grendel info you have up there. muzzle energy is 1160 to 1260 at 500 yards. The only Grendel round on Hornady's website shows 856 ft-lbs at 500 yards. That's not even the same ballpark.

If you have to pick an abnormally light bullet in the .308 to make that comparison work, then there's nothing "typical" about it. Sure, I could load a wiffle ball into an M1 Abrams main gun, and your 6.5 grendel would have better ballistics at 500 yards. So what? Nobody loads wiffle balls in an Abrams main gun.

WOW.

Oh, and it's easy to throw in specious "typical loads" when you don't list specific load data. If you compared apples to apples, your numbers wouldn't look so hot.

3 factors matter for downrange energy/velocity: initial velocity, bullet weight, and ballistic coefficient. It doesn't matter what cartridge it started in if all other things are equal. The thing is, a .308 has better velocity AND bullet weight. The 123gr Amax from the grendel comes out at a BC of .501. The 168gr. V-MAX (Used in the 168 gr TAP) comes in at .475. That's a fairly small difference in BC to overcome a 45 grain weight AND 80fps velocity advantage.

Sonic_mike
09-23-2012, 5:12 PM
I have no dog in this fight but I just can't take wash serious with the tranny Indian he has as his sig picture.

k1dude
09-23-2012, 5:31 PM
So what do you two want me to compare? A 90 gr 6.5 with a 110 gr .308? That's a 20 gr difference. Or maybe you want me to compare a 123 gr 6.5 with a 150 gr .308? That's a 27 gr difference. I know, I know!!! Lets show a super hot loaded 200 gr .308 is superior to a bulk loaded 100 gr 6.5!!! Yeah! That's the ticket! That'll show that idiot k1dude!!!

Get real. I can't believe I have to even explain this to you two. What is this - ballistics 101? Are you two sure you even own guns? You have to compare apples to apples, not apples to oranges. The two closest weights in equal loadings are a 110 gr .308 with a 123 gr 6.5. That's a 13 gr difference. I could get it down to 10 gr, but those loads aren't close enough to compare. Did you know there is no known 150 gr to 200 gr bullets that will fit in a Grendel? So how am I supposed to compare them to 150 gr to 200 gr .308?

I'm done with this argument. No matter how many times I prove you wrong you keep coming back with more BS for me to disprove. It's getting tiresome. Take you combined wisdom over to 65grendel.com and prepare to get spanked with fact.

I had no dog in the fight until about a year ago. I just wanted the best hunting cartridge that I could find for western hunting that fit in an AR-15 platform. So I did a few years of research and finally pulled the trigger on the Grendel. Do the research and leave your bias' at home. You'll come to the same conclusion. Deal with the facts, not your emotions.

I'm done here. Have fun.

The Virus
09-23-2012, 5:33 PM
build a lightweight simple 3 gun style rifle
16"barrel, tubular long hand guard, fixed stock, S3G trigger, 1-4 optic, compensator, featureless build.

k1dude
09-23-2012, 5:42 PM
build a lightweight simple 3 gun style rifle
16"barrel, tubular long hand guard, fixed stock, S3G trigger, 1-4 optic, compensator, featureless build.

That's a good recommendation if the OP shoots competition. But I would ammend your 1-4x to one of the new 1-6x optics that are coming out now - simply for more flexibility. My 1-4x is barely serviceable in the 3-gun "precision rifle" stages. Those targets get awfully small.

wash
09-23-2012, 6:38 PM
Well typical would seem to me a round commonly used in a gun with that chambering.

So a 123 grain Lapua Scenar 6.5 Grendle is typical and a 150 or 168 grain .308 is typical and for argument's sake and since the Grendle gets a Scenar, a typical 6.8 SPC is a Barnes 95 grain TTSX.

If you want to compare, compare those, not an M1 carbine bullet in a .308 case.

I bet you can get 168 grain gold medal match .308 for about the same price as that Grendle ammo and you have a much easier time finding it on the shelf.

wash
09-23-2012, 6:51 PM
My .458 SOCOM is inferior to a .17 HM2 if I have to load a .410 gauge shot cup so the "bullet" weight is almost equal.

0331Marine
09-23-2012, 6:54 PM
5.45X39...PSA has uppers for $269......

sunborder
09-23-2012, 7:23 PM
If you put the same engine in a volkswagon as you do in a porsche, you're not really comparing a VW to a porsche anymore.

That was kind of the point I was making earlier. Your comparison data doesn't pass the smell test. It's so way out of left field that any competent handloader or competition shooter is going to question it. You can twist around what your definition of "typical" is, but that's the sort of sophistry that I wish I heard less of from Washington and Sacramento.

If your original statement read something like "a hot-loaded heavy-for-caliber spitzer bullet in a 6.5grendel cartridge outperforms a mismatched light-for-caliber .30 carbine round-nose bullet in a .308 case," then you might have been half-right (even the bad data you posted isn't conclusive for your argument). As your original statement stands, it's misleading at best, and could--at worst--be seen as dishonest or the mark of someone repeating something they heard somewhere else, but didn't really understand the nuances (and flaws) of. I'm going to give you the benefit of the doubt, but please consider:

What do people shoot in their .308 guns? 150-168 grain bullets.

What do people shoot in their 6.5 Grendel guns? 110-123gr bullets.

And BTW, the Hornady grendel round is NOT a bulk round. That's a match bullet. TAP-FPD rounds actually are a bit SLOWER than max published data, by about 100-150 fps.

*****

Also, enough with the fanboy stuff please. "spanked?" "proved with fact?" Dumping HALF ther pertinent data on a given cartridge and load in a "table" doesn't prove much of anything. This is the sort of sloppy, yet strident writing that gets kids an "F" in my composition classes. If you want to assert things, you must provide ALL the *relevant* facts, make sure they are correct (yours were somewhat close, but not correct, and wrong in a few key areas, according to Hornady's data for loaded ammo available for sale as of today's date), and try to show that you at least are willing to consider an opposing viewpoint without dismissing it out of hand. You may also want to consider that the site you mentioned is not exactly an unbiased source, and the only source you listed that would be relatively unbiased (Hornady) you provided bum (or at least incomplete or out of date) data for.

I think you need to calm down a little and discuss the specific points that were raised (for example, your definition of "typical" doesn't seem to match anyone else's unless they are a hard-core 6.5 fanboy), rather than ad-hominem attacks on people. Nobody called you an idiot. We just questioned your data. Please clarify your data.

I believe that the 6.5 is a serviceable round with a certain niche. I've considered owning one, but I just can't afford an intermediate cartridge upper at this time. 6.8 is also on the list of things I'm looking at for the future.

None of us would want to be shot with any of these.

As for the OP's question: you might want to avoid all of this 6.5/6.8 stuff altogether, unless you like flame wars. Stick with the .22 conversion, or go .300 BLK for a short-range gun.

The Virus
09-23-2012, 7:43 PM
That's a good recommendation if the OP shoots competition. But I would ammend your 1-4x to one of the new 1-6x optics that are coming out now - simply for more flexibility. My 1-4x is barely serviceable in the 3-gun "precision rifle" stages. Those targets get awfully small.

1-6 is great if you have the dough, Im not replacing my 1-4 anytime soon.
Even if he's not shooting competition that build would be a very versatile rifle.

ar15barrels
09-23-2012, 8:40 PM
When Remington submitted 6.8 SPC to SAAMI, they screwed up the throat or something.

Not so.
I was around the 6.8 spc when it was just getting started in 2003 and 2004 and I can tell you how the two chambers really came to be...

So when the cartridge was first released, you could not get ammo from anyone unless Remington law enforcement division would sell it to you.
I still have some of the original pre-production ammo that met the original specs.
Someone ran some tests with this initial ammo including baking it to 130 degrees as that was the spec that they wanted to meet for use in the sandbox.
Well, at 130degrees, you can imagine that pressure were higher than they wanted.
In response, Remington lowered the pressures and the result is a loss of 200fps across the board.
I also have some of the early production ammo and if you search the web enough, you will likely run into my barrel length vs. velocity results from the testing I did during a group buy where I just happened to be testing 15 or so spc barrels all of the same manufacturer of barrel blanks, but in all different finish lengths.

So, while Remington was re-grouping, Silver state armory started up and actually started producing ammo.
The initial silver state ammo used proper 115gr Remington metal cased bullets loaded to the lower performance threshold that was determined to be safer to sell to the public.
Silver state armory was actually the first to have widely available ammo for sale to the public.
Demand was huge of course and as a way to produce a lower cost option, silver state purchased copper clad cast bullets for their cheap ammo.
Now, you need to realize that copper clad cast bullets are generally not used in rifles as the jackets are not strong enough to withstand the 50,000psi and even higher pressure levels that rifle cartridges run at.
Copper clad cast bullets are generally restricted to handgun cartridges and 30 carbine is about the hottest cartridge that can't safely use copper clad cast bullets.

Here is a close-up scaled drawing of a 6.8spc chamber showing the cartridge case, bullet and chamber clearances:
http://ar15barrels.com/tech/68throat.gif

So the issue with jacket strength goes like this: when the pressure builds in the cartridge, the bullet moves forward out of the case into into the throat.
Then pressure increases until the bullet gets pushed into the rifling (we call this obturation).
Now, you have to realize that there is clearance around the case neck of a loaded round.
This is so that the case can expand and release the bullet into the throat and bore.
While the bullet is engraving in the throat, part of the shank is hanging back into the neck of the case.
With a traditional drawn cup and core rifle bullet, the jacket is strong enough to retain its shape while the front half of the bullet engraves.
Then the rest of the bullet continues engraving until it is fully in the rifling and continues its trip down the barrel.
The problem that the copper clad cast bullets had is that the very thin copper plating has no structural strength like a traditional rifle bullet jacket.
So what happened with the copper clad bullets when they start engraving is that the rear half of the bullet would expand in the case neck and also out into the area just forward of the case neck but before the throat.

Here is the resulting ring that's left in the chamber from a bullet failure described above:
http://ar15barrels.com/tech/extreme-bullet-jacket-ring.jpg


Then, as the front of the bullet engraved and the rear part expanded, the rear part got locked into the barrel.
This causes a big pressure spike that then ripped the expanded part of the bullet off the rest of the bullet and drove the rest of the bullet down the barrel, leaving a lead ring in the chamber.
The resulting pressure spike was blowing primers and causing all sorts of problems as evidenced by the case in the picture above.

The solution that silver state came up with was to extend the throat by about 1/10 of an inch.
This extended throat let the whole copper clad cast bullet get into the freeborn BEFORE the front half of the bullet began engraving.
With the bullet fully supported in the throat, it was able to squirt down the barrel without leaving any of it's rear end in the chamber.
Now, when you extend a chamber throat, you effectively create a longer cartridge which means that you will lose performance with ammo that was developed for a shorter "SAAMI" throat.
So, the extended throat of the SPC II actually exists to solve the problem that the inferior bullets created.
The problem with those bullets was so widespread that silver state eventually pulled them off the market.
This did not happen for a few years though and by that time, the SPC II had gained traction and silver state was even offering ammo loaded to two different spec, the higher pressure for use with longer throats and the lower pressure for use in standard SAAMI throats.



The revised 6.8 SPC II chamber (much the same as the original 6.8 SPC before Remington screwed it up) uses ammo loaded with the same dies but can use faster powders because the initial pressure spike is nowhere near as high. That translates to higher velocity with lower chamber pressures.

The pressure is lower in an SPC II chamber because there is more chamber volume when the bullet moves forward more before starting to obturate.
This is much the same trick that weatherby uses to gain hidgher velocity from all of their cartridges.

We're it not for the inappropriate copper clad bullets being used, there never would be a 2nd version of the SPC chamber.

wash
09-23-2012, 9:56 PM
Well all I can say to that is that it doesn't directly contradict what I've heard but it's worded a little differently.

With that said, since the SPC II chamber doesn't seem to negatively impact accuracy and you get a couple hundred fps for free, I don't see how the original chamber wasn't screwed up...

Maybe the SPC II isn't up to "precision rifle" standards but I've seen 5" groups at 500 yards from an SPC II (not mine) which I think is more than good enough for a really good 300 yard semi-automatic hunting rifle.

mike_the_wino
09-24-2012, 10:35 AM
Thanks ar15barrels that was a nice write-up. Learned a lot from it.

mike_the_wino
10-06-2012, 12:31 PM
Long talk with owner of Load X ammo (http://www.loadxammo.com/) on this subject. Just so happens he was looking at the same thing for a client. He was finding some of the same things that wash pointed out: different barrel lengths, bullet weights all being lined up like they were the same. Obviously they are not. Kicked around a few other options but final decision is:
16" 6.8SPC

Thank you all for your input. I appreciate.