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6.5 grendel has the most potential

I remember when that steel core ammo was cheap

Quoted: I own a 6.8 a 762x39 (762 Russian) and 300 Whisper. Between the 3, they have different applications for my uses. The 300 Whisper is fantastic subsonic with a can. Check out www.quarterbore.com for the dedicated 300 Whisper forums. FYI the 300 Whisper is also know as 300/221 fireball. Barrels and kits can be had from Noveske Rifleworks ( I have this barrel and love it), Del-ton (sponsor of this site) and model 1 sales, also you can buy a rifle from SSK Industries the designer of the 300 Whisper round. JD Jones is a legend. As for the 6.8 and 762x39 they are both accurate in AR's. Dont snuff out the 762x39 because of the AK platform, Model 1 sales and DPMS have 762x49 AR offerings and word is Armalite is coming out with one. The 762x39 reviews in AR variants section have been getting rave reviews for accuracy and function... As for the 6.8: Almost every MAJOR AR mfg and custom shop makes an AR in 6.8 so that says something... Off the top, Remington, Ruger, RRA, Bushmaster, DPMS, HK, LWRC, Barrett, MSTN, DENNY/GTS, the ACR is said to be offered in 6.8 later, Stag, Noveske, and more. Cans from ACC, Surefire and someone else I am blanking on. Ammo from Silver State Armory, Hornady (tap and non tap) and Remington. As to "more potential" thats a subjective term, treat it accordingly... Penetrating power, hmm a 762x39 steel core would be my best guess... hard to find these days though.

I happen to have 500 rds of this.

are 16" barrels just as accurat as the 20" ??

The .458 SOCOM has around the same ballistics as a .45-70.

An upper in .458 SOCOM would be my choice.

Quoted: The .458 SOCOM has around the same ballistics as a .45-70. An upper in .458 SOCOM would be my choice.

If I wanted a heavy hitter, I'd get this too.

However the OP said he didn't want big bore .  I think I have seen some guy punching groups at 800 yards with a .458 though, so OP, don't discredit this round just yet.

6.5 followed closely by 6.8.

Quoted: of the standard AR's that use the 5.56 lower, which caliber has the most punch? 7.62x39 6.5 grendel 6.8 SPC 300 fireball 5.56 in whatever grain. now I know you can get the big bores but they don't fly very far. so of the above calibers, which round has the most penatrating power?

6.5 Grendel for long range or,

50 Beowulf - for CQB

Cheers,

Sakic #19

Out of all the ones the OP listed.  6.5 Grendal would be my choice.  As a reloader, there is a far better bullet selection.

what is the cost of .458 per round? or .50 Beowolf ??

of the ones you listed the 6.5,but if your after proven power an AR10 in .308 is with out a doubt you best option .

Grendel FTW. I wish AA was quicker in licensing their great product to other sources. The only hindrance of the potential of this round is the speed in which they grant others the rights to produce their products.

Double edged sword that cuts both ways I understand, but AA seems to be shooting theirselves in their own foot on marketing.

Quoted: of the ones you listed the 6.5,but if your after proven power an AR10 in .308 is with out a doubt you best option .

Then again, in that platform, the 6.5 Creedmore is like a Grendel with a shot of adrenalin. Perfect for really long range (as if the 1200 meters a Grendel can give you isn't enough!).
Overall, I'd say the Grendel. A 123 Scenar load will give you 1200 meters worth of supersonic flight and depending the barrel and make of the upper and ammo, you can get 1/2 MOA.
Up close (less than 300 meters) the Grendel isn't much special... maybe an underachiever if you compare the KE of the 6.8, 7.62x39 and .308 but the further out you go, the better it performs (in comparison). It outperforms the .30 after 800m!
6.8 is a damn good cartridge but you have to be in the upper-middle income bracket to use it. $1+ a round... Jeez, get the Russians or Serbs to make it bulk for Christs sake! It's an AWESOME round out to 300m but for the price, I'll stick with the next best thing...
7.62x39... old faithful. Ammo choices between devastating (Glaser) to nasty (Norma/Win "hunting" rounds) to "still affordable" (surplus and Ruski). Now that CProducts put out a damn good hicap, the AR platform (XCR, ACR/Masada SCAR if they do it) is now blessed with this proven round. Also, the innacuracies of the AK are now moot with the AR platform... hell, I'm getting 1.5MOA with Wolf!
5.45 (called the .21 Ghengis in some circles) is also promising... I've had a SW upper on order for 6 months now (fuckin SW slackers... send it already!). 7N6 is a NASTY round and is cheap as hell (for the moment). There's also a good supply of commercial make in bullets from 50g to 70g.
.300 Whisper is pretty damn awesome but EXPENSIVE and you HAVE to be a reloader. Also, the REAL application of this round is for suppressed weapons... something 96% of us here are not privy to.
The pistol calibers are fun... I love my 9mm but that's not the question here.
The artillery rounds are also out from what I gather. The .458 SOCOM and .450 Bushmaster are sweet but the .50 Beowulf is a monster within 200 meters.
Anyway....
Traditional 5.56 isn't bad... the key is the right bullet. For light, unarmored targets (human) the 55g M193 is awesome against those targets. M855 (SS109) was designed to be shot through the SAW at light armored targets... hence, it under performs against those above mentioned "soft" human targets. Mk262 Mod 0/Mod 1 is awesome against soft targets and is excellent at long ranges. Frangible... close range against soft targets... devastating if not sickening!
Point being, just as the 5.56 seems to be "bullet specific" so are the other calibers and your needs should dictate what you go with.
Medium (300-600m) to long range (out to 1000m) target and hunting with the ability to stop a target dead in its tracks at close range (100m or less)... 6.5 Grendel seems to be the best all around for that app.
Close to intermediate range (CQB out to 300m), hunting and defense... 6.8 if you got the money... 7.62x39 if you're on a budget or like to practice a lot (like I do).
5.45x39 is a decent defense round (excellent against light armored targets with 7N6) like the 5.56 but cheaper to shoot.
5.56 I would put in a "versatile" category where the bullet and load depend on the application. Varmint=35-50g, defense=Glaser/frangible/55 or 75g ball, target=68-77g HP, light armor=62gM855... etc

Hope all this helped... back to my beer

Great write-up EricX.

Quoted: I remember when that steel core ammo was cheap

I remember when Nixon was President,draft beer was a dime and smokes were $1 for 3 packs

Yeah, and people would drink it 24/7 because it was so cheap.  

the budget is always  a consideration. so I am looking to get the best bang for the buck.

I have a "very decent" supply of 7.62x39 but only one gun that shoots it, SKS.

I also have a "very decent" supply of 5.56 and 3 platforms that shoot that, AR's.

I have a stripped lower that is begging to be built up.

Hence my question.

I could start a new caliber in 6.? but I most likely would be limited to just a hunting supply of ammo. under 500 rounds.

kinda makes it hard to stock up for the Obamanation rule.

As for 5.45 vs 223, the 5.45 was designed to tumble unlike the 223 so for FMJ you get alot more damage to the target.  Plus the bullet curves in tissue/gel.  I dont know how it would compare to hp and such, but for military rounds the 5.45 seems to be better.

5.56 mm round in .55 grain is designed to tumble and fragment after short penetration in soft tissue, in the neighborhood of ~ 4 inches penetration.  This drops off as the distance increases between firing and target impact.  The 5.45 has a slight advantage in same bullet weights, since the bullets will be a little longer due to the reduced diameter of the bullet.  Longer bullets tumble quicker on impact.  

If by "punch" you mean the capability of defeating cover, then the 6.5 has the highest sectional density, and will defeat barriers somewhat better than the others listed.

Quoted: what is the cost of .458 per round? or .50 Beowolf ??

Depends if you reload.

Not many companies make factory ammo for those two.

But if you reload, you'll have to find .50 ammo and Beowulf brass to load the Beowulf.  For .458 you'll have to resize .50 AE brass and find .458 bullets.  I think the latter would be easier and cheaper.

The one that hits the target in an appropriate area so as to cause immediate incapacitation.