What happened to the 6.8SPC

HappyCamper · Sep 16, 2019

More than happy to add another caliber to support once it is easily and economically supported. Why add a specialty caliber when there are more than enough to do 99% of what you need. For the fun of it? To play around with it? Sure, just don't kid yourself that's it's a go to round unless it's relatively widespread.

Speed3 · Sep 16, 2019

What advantage does this have over say 308? Less drop?

holesonpaper · Sep 16, 2019

Speed3 said:
What advantage does this have over say 308? Less drop?

The 6.8 SPC is really an attempt to upgrade the 5.56 (deliver more energy in the AR-15 platform) but has nothing (except weight and size) over the .308 (AR-10 platform).

John from MD · Sep 16, 2019

Speed3 said:
What advantage does this have over say 308? Less drop?

Less recoil.

Biggfoot44 · Sep 16, 2019

The advantage over a .308win , is that 6.8SPC is uses in an AR-15 platform .

From a .mil viewpoint , the 6.8 is more suited for beltfed .

There is a potentially significant niche for AR-15 caliber significantly larger than .22 , powerful enough for Bambi , and meaningfully flatter shooting than 7.62x39 .

A few years ago ( just before the most recent ammo shortage ) , the 6.8SPC and 6.5G were equally poised to become that cartridge . My prediction was that the first one that had ammo commonly available on Wal Mart shelves would be the commonly used cal, and the other a niche trivia question .

Were these two the only contenders for the role ? Nah . Among the many :

6x45 ( once chambered by, and mildly promoted by Oly Arms )
Entire boatload of 6mm wildcat & small maker proprietary ctgs intended for long range target shooting .
.25 Copperhead ( wildcat)
.25 Sharps
.277 Wolverine
Various 7mm wildcats .

lazarus · Sep 16, 2019

6.5 Grendel is pretty close to 168gr .308 ballistics, but obviously way less recoil. Less energy too, but they’ve got roughly similar bullet drop and wind drift.

As a comparison, out of a 20” barrel a spicy 5.56 has 1300ft-lbs. a spicy 6.5 grendel is 1700. A hot .308 is 2600ft-lbs. 6.5G is certainly closer to 5.56 than .308, but it’s a lot hotter than 5.56 still. Or 300BO which tops out around 1400. 6.8SPC can hit about 1800ft-lbs, but it’s a fatter, less aerodynamic bullet. So generally it’s got less energy than 6.5 grendel by 300yds and significantly more drop by 500.

Happy...depends on what you mean as go to. I can legitimately hunt deer with 6.5 grendel. I can also shoot to 1000yds with the same rifle. It’s mild enough my kid can shoot it fine. It chambers in my AR-15. I can find high quality ammo for less than $1 a round.

Bass pro and cabelas both (usually) stock it. I think the most common ads I get in my email for AR parts are 1) 5.56/.223 barrels, uppers and rifles, 2) .308 AR-10 uppers and rifles, 3) 6.5 grendel barrels, uppers and rifles.

4th are 300BO stuff and a distant 5th is 6.8SPC and 224 Valkyrie.

erwos · Sep 17, 2019

lazarus said:
4th are 300BO stuff and a distant 5th is 6.8SPC and 224 Valkyrie.

224 Valk was almost DOA to begin with. Lot of marketing hype helped prop it up initially, but then everyone looked at the data and was like "so it's 5.56, with a slightly bigger case?" Not exactly a compelling sales pitch. (If we're spitballing cooler stuff, I think the possibility of chopping 308 down and then necking it to 224 in an OAL that could fit in an AR magazine well with Valk-weight bullets might have some interesting merits as a long-range play. Probably would need custom mags to make it feed reliably, unfortunately.)

The thing I am definitely most excited about these days is the possibility of cheap steel-cased subsonic 7.62x39 imports. THAT would be a game changer for that caliber. Just gotta wait for K-VAR's exclusivity agreement to expire.

John from MD · Sep 17, 2019

erwos said:
(If we're spitballing cooler stuff, I think the possibility of chopping 308 down and then necking it to 224 in an OAL that could fit in an AR magazine well with Valk-weight bullets might have some interesting merits as a long-range play.

That kind of cartridge would be super overbore leading to burned out leads in less than half a .223 barrel life. If used for hunting, it would probably work well. If used for frequent target shooting it would get expensive.

erwos · Sep 17, 2019

John from MD said:
That kind of cartridge would be super overbore leading to burned out leads in less than half a .223 barrel life. If used for hunting, it would probably work well. If used for frequent target shooting it would get expensive.

Two points:
1. You'd be cutting it down pretty far in order to make AR mag OALs. I don't think it would necessarily be as hot as you might imagine.
2. Replacing AR barrels is cheap compared to replacing bolt gun barrels.

Another way you could play it is to neck it to like 6.5 or 6.8 - maybe like a shortened version of 270 Redding. Depends on what you're trying to get out of it.

John from MD · Sep 17, 2019

erwos said:
Two points:
1. You'd be cutting it down pretty far in order to make AR mag OALs. I don't think it would necessarily be as hot as you might imagine.
2. Replacing AR barrels is cheap compared to replacing bolt gun barrels.

Another way you could play it is to neck it to like 6.5 or 6.8 - maybe like a shortened version of 270 Redding. Depends on what you're trying to get out of it.

1 Possibly. I was envisioning a .308 receiver and not a .223 sized.

2. True, assuming multiple manufacturers picked up on it. If you only have the high dollar places like Lilja, White Oak and Krieger, they are still going to be expensive.

lazarus · Sep 17, 2019

erwos said:
224 Valk was almost DOA to begin with. Lot of marketing hype helped prop it up initially, but then everyone looked at the data and was like "so it's 5.56, with a slightly bigger case?" Not exactly a compelling sales pitch. (If we're spitballing cooler stuff, I think the possibility of chopping 308 down and then necking it to 224 in an OAL that could fit in an AR magazine well with Valk-weight bullets might have some interesting merits as a long-range play. Probably would need custom mags to make it feed reliably, unfortunately.)

The thing I am definitely most excited about these days is the possibility of cheap steel-cased subsonic 7.62x39 imports. THAT would be a game changer for that caliber. Just gotta wait for K-VAR's exclusivity agreement to expire.

I am intrigued by 7.62x39 subsonic. PPU makes some that’s 170 something grains. I’ve heard mixed things. I’d be curious if it would cycle my SKS. Even without a can that would probably be a lot quieter and certainly less recoil. Good way to get my oldest shooting centerfire.

danb · Sep 17, 2019

7.62x39 subsonic is not cheap to shoot though. One would think it would be easy to find, like 300blk subsonic, but at a lower price point - but its really not. Seems like a specialty product.

danb · Sep 17, 2019

and to add: if you are going subsonic ... just go 147 gr 9mm in an AR platform. its subsonic too, and has about 75% of the energy of a 200 gr 30 caliber subsonic.

erwos · Sep 17, 2019

danb said:
7.62x39 subsonic is not cheap to shoot though. One would think it would be easy to find, like 300blk subsonic, but at a lower price point - but its really not. Seems like a specialty product.

It's expensive because K-VAR has an exclusivity agreement. The stuff is extremely cheap in Russia, and could be imported here at very favorable prices.

alucard0822 · Sep 17, 2019

danb said:
and to add: if you are going subsonic ... just go 147 gr 9mm in an AR platform. its subsonic too, and has about 75% of the energy of a 200 gr 30 caliber subsonic.

300BO ends up about double the energy once you get around 200 yards, much flatter shooting subsonic vs subsonic too. Can hit steel plates at 200 with my 9mm PCC, but it's nowhere near practical or consistent at that range, 300BO can ring it all day, or load supersonic ammo and hit plates twice that far.

danb · Sep 17, 2019

erwos said:
It's expensive because K-VAR has an exclusivity agreement. The stuff is extremely cheap in Russia, and could be imported here at very favorable prices.

exclusive? Engel and Atomic (and I think a few others) sell it.

danb · Sep 17, 2019

alucard0822 said:
300BO ends up about double the energy once you get around 200 yards, much flatter shooting subsonic vs subsonic too. Can hit steel plates at 200 with my 9mm PCC, but it's nowhere near practical or consistent at that range, 300BO can ring it all day, or load supersonic ammo and hit plates twice that far.

Sort of yes/no. All depends what bullets you are comparing. http://www.shooterscalculator.com/ballistic-trajectory-chart.php

It will depend on the bullet, specifically, the ballistic coefficient. Given the same initial speed and same drag both trajectories are identical, because physics.

For subsonics, the bullet matters (specifically, the ballistic coefficient). The Hornady 147gr XTP Flexlock bullet has a BC of .212, while the Hornady 110gr VMAX 300 blk has a BC of .29. The velocity difference will be 809 vs 881 fps, so the 9mm will have 65% of the energy. I can no doubt find examples where the 9mm is "flatter" than 300 blk if I choose the "right" low drag 9mm and "wrong" high drag 300blk.

Its all a drag!

I can hit 200yd steel no problem with my 9mm AR, if I choose something other than say cheap Blazer.

erwos · Sep 17, 2019

danb said:
exclusive? Engel and Atomic (and I think a few others) sell it.

They're not selling the Russian imports.

danb · Sep 17, 2019

erwos said:
They're not selling the Russian imports.

I see what you mean. Yeah, the russian imported subsonic does not appear to be russian imported prices!

alucard0822 · Sep 17, 2019

danb said:
Sort of yes/no. All depends what bullets you are comparing. http://www.shooterscalculator.com/ballistic-trajectory-chart.php

It will depend on the bullet, specifically, the ballistic coefficient. Given the same initial speed and same drag both trajectories are identical, because physics.

For subsonics, the bullet matters (specifically, the ballistic coefficient). The Hornady 147gr XTP Flexlock bullet has a BC of .212, while the Hornady 110gr VMAX 300 blk has a BC of .29. The velocity difference will be 809 vs 881 fps, so the 9mm will have 65% of the energy. I can no doubt find examples where the 9mm is "flatter" than 300 blk if I choose the "right" low drag 9mm and "wrong" high drag 300blk.

Its all a drag!

I can hit 200yd steel no problem with my 9mm AR, if I choose something other than say cheap Blazer.

thing is nobody loads the 110 in subsonic, and most are around 1000fps in 300BO, most any sub load is going to be 200+gr with .600 or better BC. At 300 yards a 147gr 9mm@1KFPS has lost almost 1/2 it's energy and around 750fps, a 300BO at the same muzzle velocity and distance has only lost about 75FPS compared to the muzzle velocity.

What happened to the 6.8SPC

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