308 vs 6.5 Grendel vs 6.8 SPC

Howdy,

I vote for the .308. It passes the WalMart test, currently in the USA supply system, and has enough off the shelf loadings to be confusing! Though the Grendel and the SPC are interesting, they both have small followings. There are 100's of good cartridges that didn't make it, 5mm Browning, .284 Win, .41AE just to name a few. Unless your into "exotics", stay mainstream and enjoy it for years to come.

Of the three, I only own 6.8 SPC for whitetail deer within 200 yards. I chose it because, at the time, it was more reliable in AR15's with standard ejection ports, than 6.5 Grendel. Now, it is a toss-up, depending on the use. For either the Grendel or SPC, I would stick with AR15. The Grendel does have the edge in range, and you can get similar bullet weights for both, so cost is the big detractor with Grendel. However, .308 is a good all-around chambering, plentiful ammo, lots of firearms choices, good ballistics at ranges, etc. AR10, SCAR, M1A; all comes down to personal ergonomics.

Just my opinion, but it sounds like you want one rifle to do everything, which is going to be a compromised package. Is there any chance of buying two rifles; a hunting rifle in 308 and a battle rifle in 223?

For what the DPMS costs you could get a Colt 6920 with aimpoint clone and decent bolt action with 2-7x scope.

What is "long range, rapid fire defense"? What are you "defending" against? Are you handloading or limited to purchasing commercially loaded ammo?

I own both a .308 AR and a 6.8 SPC AR-15. The .308 is nowhere near "lightweight". I handload for both. If I didn't handload, I'd go with the .308 GII DPMS. If I handloaded, I'd look seriously into both the 6.5 and 6.8 options. The 6.5 seems to have a better option of commercially loaded "match" ammo, but the 6.8 has a lot of great hunting ammo options. Good luck.

The 6.5 Grendel is a junk caliber. They break either bolt lugs or extractors depending on whether you have the type 1 mis-design or the type 2 mis-design.

6.8 SPC is somewhat better in terms of reliability and has better terminal ballistics, but is limited at long range.

.308 gives you the best long range performance potential of the 3, the best terminal ballistics for both hunting and anti-personnel, the most testing from a reliability standpoint, and the best ammo availability.

This one's not even close.

.308 gives you the best long range performance potential of the 3, the best terminal ballistics for both hunting and anti-personnel, the most testing from a reliability standpoint, and the best ammo availability.

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.308 ammo is also less expensive at a given quality/performance level, despite using more metal. And there is no milsurp 6.5 or 6.8 that I know of.

I like the idea of the larger calibers in an AR15, but none of them seem to fully make sense if .308 is an option, except for 6.8 SPC in limited instances where weight and size is critical and cost doesn't matter much.

I've got a few 308 ARs and now because of ostioprosis I'm wanting something with softer recoil but longer reach than 223 ... Legal hunting caliber is a bonus so I'm looking at the 260 Remington and 6.5 Creedmore ... Leaning to the Creedmore ... While there is a small selection of 260 on the shelves and zero Creedmore, the 6.5 Creedmore has better ballistics and I'll be loading for it so that is mostly irrelevant

This one's not even close.

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Yeah, unless you want a smaller rifle than an AR10 with less recoil...

For a factory ammo available caliber in the lightweight AR-15 platform you have the "king of the woods" in the .30 Remington AR. For energy (what it takes to ethically kill game) it is the best there is for the AR-15 platform it beats 6.8 and 6.5 Grendel all the way to 300 yards.

For a handloader it gets even better for the 30 Rem AR as you can duplicate the .300 Savage ballistics and it nips at the heels of 308 factory ammo. But as a handloader I like different calibers so I have a wildcat called the 7mm Valkyrie it duplicates 7-08 factory ammo in same length barrels.

If weight doesn't bother you much and readily available ammo is needed then the clear answer is .308 Winchester

Huntolive said:

"The 6.5 Grendel is a junk caliber. They break either bolt lugs or extractors depending on whether you have the type 1 mis-design or the type 2 mis-design."

How many of you agree w/ this statement? Why, why not, and based on what data?

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The 5.56 AR already is at the hairy edge of breaking bolts - that's why we've got bolts in special steels, MPI, etc. The 6.5 Grendel has about 30% more bolt thrust than the 5.56 due to much larger case diameter AND removes material from the bolt in two dimensions to fit the bigger case head. There's simply no way it can work, and experience has shown that to be true. This is the "type 1" mis-design.

The type 2 mis-design adds back steel to the bolt, and to make space thins out the extractor. With predictable results.

The AR design was simply not made with extra space. Stoner scaled it down to fit the cartridge. Things like 6x45 work fine, because they use the .223 case head. But I wouldn't really recommend going much bigger. 6.8 SPC is marginal.

There was a bolt thrust issue if you load it to the full 50-60ksi the brass is rated for (and which most smaller-case cartridges in the AR operate at), but a combination of 9130 bolts and backing off on the pressures to around 40ksi or so seems to have alleviated the issue from what I've been able to determine from my research. Same issues as when WSSM's were first put out there; handloaders, giddy with the possibility to duplicate much larger cartridges' performance from a short action, found they were exceeding bolt thrust allowables, and had to back off somewhat.

The fact still remains that with Grendel a handloader gets a wide variety of bullets for a wide variety of purposes (except practice, since I don't know if there's a cheap 6.5 FMJ out there), excellent ballistics mimicking 7.62 NATO out to 800yds or so (and better than 7.62 past that point), and plenty of terminal performance for anything that isn't armored or hiding behind cover out to the same distance. Obviously 7.62 hits harder, it has like twice the powder and half again as much bullet mass, but the rifles that can fire it are typically pushing ten pounds with any kind of full length barrel, and are at a minimum two inches longer apart from that for the extra action length. 7.62 also makes a ton of noise (I gather Grendel is no picnic, though) and a lot more recoil than the smaller round.

If 308 is a consideration, 6.5 Creedmore makes a lot more sense if you're hell bent on going with a longer length action, since it really does get better performance in almost all areas. 6.5 Grendel has similar advantages over same-length rounds in the AR platform, retaining down range accuracy & ballistic performance with a heavy-for-caliber bullet. 6.8SPC is so much more similar to Grendel than these other cartridges mentioned, that you should see them as identical (really, the only difference is that you won't find as many long-ogive match bullets for SPC since there's no room for their length, and that 6.8 barrels are apparently is much better/cheaper supply for the moment)

Grendel also requires proprietary mags, don't forget. They're like 12$ and available, so it's not too bad unless you need them & aren't able to find any during a panic, or whatever.

There's simply no way it can work, and experience has shown that to be true. This is the "type 1" mis-design.

The type 2 mis-design adds back steel to the bolt, and to make space thins out the extractor. With predictable results."
And yet, the caliber works great for a lot of satisfied shooters. BTW, the 'type 2' or whatever was due to LWRC trying to imitate the barrel/bolt setup using standard 7.62x39 AR bolts when the Grendel set were in short supply. The reason this wasn't done originally is because, as you say, the extractor hook geometry is wrong the case it was based on, the 220 Russian, which apparently has a thicker rim than x39 (so dropping the bolt face back allows a standard x39 extractor to seat in the groove). There was also some tweaking to the chamber leade, to 'soften' the transition for the bullet as it is swaged down, which had the effect of markedly reducing peak pressure/bolt thrust (also contributing to more acceptable bolt longevity)

"The AR design was simply not made with extra space"
Agreed. But sadly, because of the AR's dominance on the market, otherwise excellent cartridge designs like Grendel are forced to make due with what is available. Same reason the 50 Beowulf has a goofy rebated case head so it can use the same bolt as the Grendel (AA didn't want to pay to have two different bolt produced/developed). Personally, I've been waiting for someone to make an AR15-length upper that uses AR10 barrel & bolt components, but an AR15-diameter carrier, which would far more than enough margin to contain full-on nuclear Grendel loads that truly do approach 6.5x55 Swede (this being the dragon chased until bolts broke in the first place)

TCB

6.5 Grendel

The gun will be lighter, there are a zillion aftermarket goodies for AR-15s, and it should shoot flatter than a 6.8

It will not preform as well as the .308 but should be good enough to kill deer and hogs, probably out to about 300 or 400 yards. I don't know about 800. You can hit paper / steel at 800 no problem but you've only got maybe 500 foot-pounds of energy left at that range that's pretty iffy for deer if you ask me.

I'm attaching a chart showing bullet drop, wind drift (5mph wind at 90 degree angle), and energy, for .223 vs 6.5 Gren. This is assuming you're shooting 55g .223 and 123gr 6.5

The 6.5 should be much better in terms of both energy and wind drift than the .223

Also "light weight" and "800 yards" are pretty much mutually exclusive

Maybe get a heavy barrel with fluting to reduce weight?

.260 will not work in an AR-15 but should work in an AR-10 just fine. It's basically a .308 case with 6.5mm bullets

I might be a bit of an outlier in this crowd, but I think that given your requirements, the 6.8 SPC makes the most sense.

I've never had a 6.5 G, but I've had a 6.8 AR-15, and a .308 M&P-10. While there are lighter AR-10 style rifles out these days (the M&P-10 is one of them) you will always be able to buy or build a lighter, shorter, handier AR-15 pattern rifle than you will an AR-10 style rifle, everything is just a little bigger on the AR-10.

Any of your choices would, at least for me, be solid 200 yd to 250 yd hunting rifles, for anything further than that I'd rather have a bolt gun. At those ranges (which cover a large portion of deer or hog hunting), the differences between the 6.5 and 6.8 are really negligible, to the point of not having an impact on real hunting scenarios.

The advantages I see for the 6.8 over the 6.5 is the much wider availability of ammunition, from more manufacturers (17 loads from 5 manufacturers for the 6.8, and 5 loads from 2 manufacturers for the 6.5 on Midway). The 6.8 is also well supported by upper manufacturers, with decent uppers or barrels available from several companies (although the 6.5 is getting a little better on this front). Lastly, there aren't any systemic issues with 6.8 bolts, which there may or may not be with current production 6.5 G bolts (depends on who you listen to).

If I was going to get another AR carbine for woods type hunting, it would probably be another 16" or 18" slender barreled 6.8 SPC built out to be lightweight and handy. Easy to carry around, fast follow ups, not much recoil and I can verify that a 110gr Accubond at 2,660 fps turns out the lights out on deer very quickly.

AR10 in .260 sounds perfect.

I would add pocket carry to your list of features

6.8 spc is great and getting better still. Meets criteria listed well.

.277 Wolverine (6.8x39mm), which produces 6.8 SPC performance from a 5.56 case. Uses 5.56 magazines and bolt. Only need a barrel (and reloading dies).

Shawn Dodson said:

.277 Wolverine (6.8x39mm), which produces 6.8 SPC performance from a 5.56 case. Uses 5.56 magazines and bolt. Only need a barrel (and reloading dies).

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Let's not get crazy now. The 277WLV does not produce the same performance as a 6.8 SPC.