Why is 6.8 SPC still a thing when 6.5 Grendel is more and more popular?

[LRRPF52]

This isn't meant to be a touchy subject nor picking on other people's flavors. We can have this discussion as those interested in firearms without those on one side feeling picked on.

As LRRPF52 has shown several times on this forum, 6.5 Grendel >>> 6.8 SPC in every way. From long range precision shooting, to hunting loads, to SBR, to suppressed...etc. I don't know of one thing that the 6.8 offers that the 6.5 also matches and if not exceeds in performance. I don't know in what case one would pick a 6.8 SPC over a 6.5G, if for no other purpose than to be different. If looking strictly at performance, I don't see any case where the 6.8 SPC performs any better.

Because 6.8 SPC actually has case taper for better feeding for automatic combat weapons, unlike the weak 6.5 Grendel with no real taper on the sidewalls.


Not enough case taper 6.5 Grendel (L), Plenty of case taper 5.56 (M), Plenty of case taper 7.62x51 NATO ®-It helps if you don't think about it and just repeat what you've been told by someone else.



Because 6.5 Grendel doesn't have case taper, it can't run full auto.

[video=youtube;QzEHPbd3t3M]https://www.youtube.com/watch?v=QzEHPbd3t3M[/video]

The Grendel fanbois will tell you that there are 10,000 usable bullets for Grendel...most are target bullets and most are too heavy to get decent velocity so they expand properly especially at the yardage where it is claimed to perform better than the 6.8. If you reload the 6.8 can be loaded hotter than the grendel and gain 100-150fps.

I guess I can't count right because every time I add up the hunting bullets for 6.5 Grendel, they far exceed the count of the target bullets. Maybe one day I'll be able to to do basic math....

If you are using a 16" barrel or less,
About 90% of hunting shots are inside 200 yards...and here the 6.8 has more performance.
10% of hunting shots - From 200-300 they are about tied, but if hand loaded the 6.8 can still out-perform at those distances.
1% of hunting shots - Over 300-400, the Grendel pulls ahead unless the 6.8 is hand loaded, in which case they are about tied.
0% of ethical hunting shots on game - Over 400, if you want to hunt, you really should get a different round as neither have great energy and expansion.

Meaning, if you are using a 16" barrel or less...
With factory ammo - The 6.8 is more capable 90% of the time, tied about 9% of the time, and the Grendel is better for 1% of your ethical shots.
With hand loads - The 6.8 is more capable 99% of the time and tied about 1% of your ethical shots.

Prepare for best performance for 99-100% of my ethical shots vs. 0-1% since I didn't want to carry a 20-24" barrel? That decision was easy for me.
I went 6.8, since I carry either a 12.5" pistol or a 16" rifle.


16" 6.5 Grendel, 123gr SST, 2440fps Hornady Mach 2.0 Doppler-based G1 BC of .493 for the first 300yds is used. .462 would be used for 1000yds, and it is much better to use G7 once you get past 600yds anyway. None of that matters because we're talking close range hunting performance anyway, so we use the Mach 2 Hornady doppler data. The stated .510 G1 BC doesn't really change it significantly within 200yds because ToF is so short.

0 2440fps 1626 ft-lbs

25 2397 1569

50 2354 1513

75 2312 1459

100 2270 1407

125 2228 1356

150 2187 1307

175 2147 1259

200 2107 1212

16" 6.8 SPC II Hornady 120gr SST, .400 G1 untested BC, 2460fps mv

0 2460fps 1612ft-lbs

25 2406fps 1543ft-lbs

50 2354 1476

75 2302 1412

100 2250 1349

125 2200 1289

150 2149 1231

175 2100 1175

200 2051 1121

Looks like the 6.8 120gr SST is going 9fps faster at 25yds! (Ignore the energy though, that doesn't matter, and ignore 50yds on out.) See, I told you the 6.8 is where the horsepower is at. If you want 6.5 Grendel, it sucks for punching paper at distance but is ok, you might as well get a 6.5 Creedmoor if you really want to shoot targets, because the 6.5 Grendel is mediocre at best for that, and we already stated a million times how it isn't good for hunting, with its target bullets and heavy barrels, so naturally, the 6.8 SPC II is the most ideal hunting cartridge you can chamber the AR15 for. Just keep repeating that and it will sink in.

That's that lying LRRPffft character cherry-picking data (from Hornady, 6.8forums, and Predator Masters forums) for 6.8 SAAMI, not SPC II! He's a liar! You can hand load the 6.8 SPC II much faster!

120gr Hornady SST- Generic Deer / Hog load
H322 26.5gr 2480fps
2.260" OAL
Rem Brass
Win LG Primers
16" barrel
Groups about 3/4" at 100yds

120gr SST Hornady- Deer / Hog load
2.260" OAL
24gr H4198 2470fps
Rem Brass
Win LG Primers
16" Barrel
Groups 3/4" at 100yds

Wilson Combat Stainless 16" 6.8 SPC II barrel
This is my hunting rifle
Optic- Leupold 2-7x33mm duplex crosshair

120gr Hornady SST's - Deer / Hog Load
loaded to 2.295" OAL
H4198 24gr = 2470fps - 2500fps
Win Large Primers
Rem Brass
Groups 1/2" at 100yds

I pushed 120 SST load dev. up to 28.2 gr. A2200 for 2737 avg. fps from my 20", but it was too hot, with erratic accuracy. 28.0 gr. is max. in my rifle, producing 2687 avg. fps and sub moa accuracy.

Load for my *** 16" Scout SPC II
SSA Brass trimmed to 1.676
CCI 41 primer
27.4 grains of AA2200
120 SST
OAL 2.290
Group Size .691" 3 shot@100yds
Avg Velocity 2481 FPS

6.8 SPC II Chamber, Hand Load, 120gr SST, .400 G1 untested BC, 2500fps
0 2500fps 1665

50 2393 1525

100 2288 1395

150 2187 1274

200 2087 1161


But don't even try to load the 6.5 Grendel faster with CFE223 or LVR, because you will get the same speeds. I hit 2550fps from one of my 16" Grendels without exceeding 50,000psi chamber pressure with the 123gr Hornady AMAX using CFE. If I was really wanting to throw caution to the wind, I would throw up the max charge I shot, but I won't because only a fool would chase those speeds. I didn't see any cratering or flattened primers until 2640fps, so if I only used those metrics as an indication of excessive pressure, I would run straight to the internet, "No pressure signs!" But because we tested the loads with calibrated instrumentation with correctly-placed gauges and many months of testing before drawing conclusions on pressure data, we know where to cut it off at.

Constructor: Who has the fastest, accurate 120gr SST load? Who has it or who can find it? I think there is a 2700fps (20" barrel)load out there. That is something to advertise the performance of the 6.8.

In that thread, they got over 2800fps with a hot load from a 24" 6.8 SPC II BHW polygonal rifled barrel!

If you want performance from the 6.5 Grendel, you need a 20-24" barrel, otherwise it just doesn't do it, and won't expand with the hunting bullets out there meant for .260 Remington.

[COLOR="#0000FF"]Well, I guess I'm headed off to the Equipment Exchange to sell all my Grendels, brass, barrels, weak bolts, mags, etc.

I'm going to step up to the hot rod performance of the 6.8 SPC II! As you can see, it will just give me more horsepower! Look at all that frontal area of the bullet too. It's much larger than the weak and anemic 6.5 Grendel.[/COLOR]