This -><- close to choosing 6.8 SPC vs 6.5 grendel

[grizzman]

From what I have read, the 6.5 Grendel out performs the .308 once you get past 600 yards. Flatter shooting and retains more energy than the .308 after 600. 0-600 the .308 is superior.

This might be the case with the 6.5 Creedmoor (depending on bullets and velocity, but not the little Grendel.

[caporider]

This might be the case with the 6.5 Creedmoor (depending on bullets and velocity, but not the little Grendel.

Exactly, depends on bullets and MV.

My 20" Howa Mini Action 6.5G bolt gun shoots 123gr SSTs at 2500fps. 4.4 mils of drop at 600 yards.

I had a 20" SR25 that shot 175gr SMKs at 2550fps, 4.7 mils of drop at 600 yards.

I can actually use a .308 BDC on my 16" 6.5G AR15 and be pretty darned close.

Yeah, Grendel doesn't use mongo 175-185gr bullets, but if you're shooting paper the round is plenty capable when compared to .308. Inside of, say, 400 yards, Grendel even manages to kill animals humanely (I know, seems impossible).

[Red*Lion]

This might be the case with the 6.5 Creedmoor (depending on bullets and velocity, but not the little Grendel.

Of course the Creedmore out does both, but the Grendel out does the .308 pretty clearly starting around 400 yards.

6.5 Grendel bullets usually retain their velocity much better than .308 bullets, extending the practical range that game may be taken. The Grendel projectile starts out much slower than .308 at the muzzle, yet is traveling substantially faster than .308 at 1000 meters. The result? The window in which Grendel bullets perform correctly is greater than the .308 window. This is because hunting bullets fail to perform well when their velocities are higher or lower than the velocity at which they were designed to perform (expand, fragment). A particular bullet design will perform well at both closer and farther ranges from a 6.5 Grendel than from a .308.

https://shwat.com/308-vs-6-5-grendel/

While it may not be a concern in the case of short-range shooting, this coefficient must be looked into if one is going for the long-range. This coefficient depends on the shape, size, weight, and velocity of the bullet. Hence, in short ranges, .308 has a higher ballistic coefficient as compared to the Grendel, but in longer ranges, the Grendel has an upper hand.

https://www.thenewsurvivalist.com/6-5-grendel-vs-308/

Distance
As mentioned earlier, a 308 requires a longer barrel to gain the required velocity for expansion for longer range hunting. The 6.5 Grendel has a big advantage in modern powders and cartridge design. It is quite efficient from a short barrel, gaining its speed rapidly.

But looking at their muzzle velocity, the team noticed that the Grendel is a little bit slower when shot at a distance of one hundred yards than the 308 or 6.5 Creedmoor. However, the velocity of the Grendel starts catching up at 200 and 300 yards. And at 400 and 500 yards shot, the Grendel surpasses the 308 in speed. This result is going to continue with further distance energy.

Ballistic Terminal
Ballistic terminal is probably one of the most notable differences between the 6.5 Grendel and 308. The size of the two bullets is pretty different and apparent. And because of their size difference, their sectional density differs, too.

For those who don’t know well, sectional density affects terminal ballistics. The 6.5 Grendel has a long and thin cartridge. When a cartridge is lighter and smaller, it penetrates your target better.

bullet exploding
After testing both cartridges for ballistics for the first time, the team found out that the velocity of both bullets is almost the same. But because 6.5 Grendel is more aerodynamic, this is where the Grendel takes another win against the 308 Winchester, which has a lower sectional density.

https://lundestudio.com/6-5-grendel-vs-308/

[grizzman]

Of course the Creedmore out does both, but the Grendel out does the .308 pretty clearly starting around 400 yards.

I, and my Sierra Infinity External Ballistics program, completely disagree. With typical bullets and identical barrel lengths, the Grendel is inferior....and I own one.

Here's a 168 grain A-Max at 2700 fps (from a 24" barrel) and a 123 grain A-Max at 2575 fps (also from a 24" barrel). At no point between 10 and 1000 yards does the Grendel have more velocity, more kinetic energy, or less drop. The Grendel does really well considering the powder capacity and overall length.

[IMG][/IMG]

[caporider]

I, and my Sierra Infinity External Ballistics program, completely disagree. With typical bullets and identical barrel lengths, the Grendel is inferior....and I own one.

Here's a 168 grain A-Max at 2700 fps (from a 24" barrel) and a 123 grain A-Max at 2575 fps (also from a 24" barrel). At no point between 10 and 1000 yards does the Grendel have more velocity, more kinetic energy, or less drop. The Grendel does really well considering the powder capacity and overall length.

[IMG][/IMG]

Are those MVs you've seen out of rifles you've shot...? Also wondering if you're comparing factory loads or hand loads.

[grizzman]

The muzzle velocities I mentioned came from QuickLOAD, and are some max loads I quickly worked up.

I used Varget for the above 2700 fps number, since that's what my saved load had as the powder. It should actually be possible to approach or surpass 2800 fps with CFE223 driving the 168 grain A-Maxes. I chose BL-C2 as the Grendel's powder, since QuickLOAD shows it to deliver as much or more velocity as 8208, H322, and Varget.

My Grendel only has an 18" tube (since it's an AR), and I've only begun load development for it. My 308s are 20", 22", and 26".

[win&legend]

All the classic "exterior ballistics" debate and the assumption that exterior ballistics is a good predictor of terminal performance or practical application. Bigger bullets leave bigger holes and smaller bullets don't always expand...lets not forget that velocity and the resulting Kinetic Energy mean very little if the bullet just zips through the target body doing too little damage and wasting most of it's paper punching KE smacking into some rock, tree or wall behind the target. Without a CNS or vital organ hit, at the ranges people are debating here often mean a week or two in the hospital....or an animal that runs off miles before it dies, or in some cases doesn't die at all and lives the left of its life maimed. An enemy combatant taking a lung or limb hit from what is now basically a low velocity small diameter FMJ....ouch but he'll most likely live with reasonable medical attention from his friends.

At the ranges 6.5 G or 6.8 SPC can achieve fragmentation or expansion velocities, they are nearly identical. Why do you think the Military is actively pursuing the NGSW project with a specification for a 6.8mm bullet? No it's not the 6.8 SPC. But they are using the data from all of the testing of 5.56 loads and development of 6.8 SPC to base that requirement on and applying it as a more effective replacement for 7.62x51mm. They can maintain most of it's terminal performance while improving it's exterior ballistic performance, making it easier to shoot at the limits of it's effective range. A better compromise than the currently available 6.5 Creedmoor vs. 7.62x51mm (aka hot .308) and from shorter barrels either existing solution can manage. Like one contender, the .270 Sig Fury, manages 3000 FPS from a 130gr 6.8mm bullet from just a 16" barrel. 5.56 isn't going anywhere any time soon. With improved 5.56 ammunition and the massive logistics of existing infrastructure (both US and NATO), it's staying despite it's limits.

Kinetic Energy Transfer - Penetration Depth Bare 10pct Gelatin.png

Kinetic Energy Transfer - Penetration Depth Auto Glass 10pct Gelatin.png

Kinetic Energy Transfer - Penetration Depth Car Door 10pct Gelatin.png

6.8 SPC is basically akin to a .270 Short, however you look at it. Slightly lighter bullets, lower velocity, but nearly identical terminal performance at ranges where fragmentation or expansion still occur. Chop off 300 yards from .270 Winchester and you have 6.8 SPC. I have zero issues with 6.5mm projectiles and cartridges, they are absolutely lethal and outperform 5.56, but I am going to accept what the US Military found as valid after very extensive data sets, both real world occurrence and ballistics testing. Some calibers perform better on average over a broad range of conditions, close, mid, barrier, nor barrier, system reliability, ammo capacity etc. are all factors.

They found 6mm and 6.5mm gave up too much terminal performance at closer ranges for very little gain in exterior ballistics at ranges any of the intermediate test cartridges were practically usable (500 to 600 yards max). So regardless of weather or not you can shoot 6.5 Grendel out to 800 to 1,000 yards, it's moving so slow, has too much drop / drift and too little KE at those ranges to be useful at killing things in the real world, making it a paper puncher at those ranges. From 0-500 yards, it's still effective even if not the most ideal at closer ranges for military applications. When people brag about this cartridge or that cartridge shooting some ridiculous range...they always seem to neglect those facts.

They also neglect that they can only accomplish that under bench rest conditions. Try using a .338 Lapua at 1,000 yards, then use the 6.5 Grendel out in field conditions, a .338 is going to fare far better even though both "can shoot that far"! Right tool for job, but some tools need to be broadly usable, even if they aren't the best at any one thing. 6.8 SPC best fits that bill for AR-15 frame sizes even though on paper it's not the best at any one specific thing compared to ever other cartridge we've discussed. It may not have been adopted for cost / logistics reasons (neither were 6.5 G or .300 BO), but it does not negate it's practical performance advantages over 5.56 NATO in small frame AR-15 applications. That's my story and I'm sticking to it, so is the US Military.

[caporider]

Try using a .338 Lapua at 1,000 yards, then use the 6.5 Grendel out in field conditions. I'll take the .338 thank you! That's my story and I'm sticking to it.

It's so much easier to see trace and splash with my 6.5 Grendel vs .338LM -- unless you're willing to live with the tradeoffs that come with a large muzzle brake. I personally hate muzzle brakes.

Yeah, if you're a legit military sniper you need something bigger than 6.5 Grendel. Police snipers would be just fine with Grendel, probably better off than with .308 in the vast majority of circumstances.

As for the military 6.8 round, that is spec'd to go nearly 3,000fps out of a 16" barrel, so there is some very new technologies being fielded in trials and the ammo, when available to civilians, will be very expensive to start. I personally am curious about these developments, but I'll be shooting my Grendels in the meantime instead of holding my breath...

[Disciple]

At the ranges 6.5 G or 6.8 SPC can achieve fragmentation or expansion velocities, they are nearly identical.

I wish there had been only one 6.X AR cartridge, perhaps half way between these. The market adoption would likely have been greater than both combined. I wouldn't care if it used a 0.264 or 0.277 bullet. Any substantial difference in ballistic or terminal performance is due to the construction and weights of bullets chosen rather than to the 5% difference in diameter. Visually this is all the difference there is between them.

[Beerswimmer]

I wanted to make a hunting AR and chose the 6.5G because of the cheap Wolf at the time. I could blast/train with it for cheap. That was my only reason since they are nearly identical at hunting ranges. If Wolf made 6.8 instead I would have gone with it instead.