Dipping my toe into the Grendel waters and kinda baffled by some of the fps/speeds I see reported by reloaders on the forums.  The group sizes are always fantastic, but the speeds are not as fast as I would expect running 85-90gr stuff. 

Are guys simply going for the smallest groupings possible in exchange for velocity? 

What's some of the faster fps one can expect from a 16" barrel? 

The lower muzzle velocity is not an issue because of the heavier bullet weight and high bullet ballistic coefficient.  From what I've read the 123gr bullets are optimum for the caliber.  My Grendel has the same POI whether I'm shooting Hornady 123gr or Wolf 100gr, and in both cases the trajectory is flatter than 5.56. At 300 yards, the Hornady still has 1000+ ft/lbs of energy, which is 300+ ft/lbs more energy than the trusty 30-30.  I don't shoot at game past 300 yards because of the significant potential for non-fatal wounding.

IMO, Hornady Black ELD Match and SST ammo rock, and Wolf steel's not bad for plinking.  I'm keeping my eyes open for some brass Wolf Gold to show up on the market again.

6.5 G isn't fast, it is efficient.
Too many get hung up on velocity. It carries its energy and effectiveness for a long way.
Speeds from a 16 inch will be slower than longer barrels, obviously, if I could load a pic from the computer, I have a ballistic chart for 16 in barrels. I found it on the internet, so look around there.
Found it, but I don't know who or when these were published, so a grain of salt may need to be added.

2550 from my 18" barrel with 123gr sst factory loads.

I reload using Alexander Arms brass (Lapua), Remington 7.5 primers, 26.0 grains of VihtaVuori N530 and 107 grain Sierra Match Kings seated at 2.2550". Velocity is 2600 fps from my 24" barrel. Much slower from my 18".

I completely ignore online accounts of high velocity loads for 6.5 Grendel or 6.8SPC. There is an entire online community that believes that they are somehow special, their rifle is special and that the laws of God and Nature do not apply to them.

If you want to go faster buy a bigger caliber.

Any quality reloading manual will list reasonable maximum velocities for any given cartridge. Pay attention to the barrel length used because it makes a big difference between what is safe and what is not.

I would feel comfortable running 90 or 95 grain 6.5 bullets up to 2700fps+. Heavier 123 grain bullets around 2450fps.

7.62x39mm and 6.5 Grendel share the same case head size which needs a bolt face very close to .450". 6.8SPC is closer to .428". 5.56mm is around .380". They all are using identical bolts other than the metal removed to make clearance for the larger diameter case heads. This weakens the bolt and pushing pressure upwards of 50,000 psi for any of the larger cases will stress an already weakened part.

Ideally a mid-sized AR frame should be developed to accommodate these larger calibers using longer overall lengths in the magazine and a beefier bolt. Something half way between an AR10 and the AR15. Instead, for expediencies sake and to allow AR owners the option of more powerful ammo, engineers shoe horned these rounds into the AR frame. I don't push it and am perfectly happy with the accuracy and increased performance as is. Others don't want to leave well enough alone.

90gr TNT Federal factory is pretty fast at the muzzle, 3000fps from a 24".

It does 2890-2905fps from my 17.6" barrel.

By 275yds, the 123gr Hornady ELD-M has caught up with the 90gr TNT for speed, but it has more energy from the muzzle on out, and way less wind drift.

What you start to see is that muzzle velocity is not the be-all/end-all in desired performance, unless you care more about bragging rights for mv and shoot things very close to the muzzle, using projectiles that are dependent on high impact speed for performance.

6.5 Grendel is the balancing point of having a lightweight, low recoil, but high retained energy on-target for such a small package.

I learned to look farther down the flight path at the numbers long ago, and the mv isn't as important to me as the BC is because of that.

With higher BC, you can exceed the speed and retained energy of other loads that shoot 300-400fps faster at the muzzle, even by 275yds, like the example mentioned above.

For those that have a hard time staying focused on big walls of text, when you hear the impact on steel, you know all you need to.

That 90gr TNT load will still flatten my 12" steel poppers at 300yds, whereas 5.56 even with a 77gr just makes a little "dink" noise at best.

With the 123gr bullets, it's a lot easier to hit in the wind, with more retained energy for effects on target.