What performance gain from an additional 10,000 or 15,000 psi?

[Fess]

The high-pressure cases being used in the NGSW trials made me wonder what would happen if a high-pressure variant of the Grendel were developed. I know that it would not work (not for long, at least) in current AR15's, but that is not the point. A beefier weapon would be needed, but that has been done before.
I have followed the cartridge since its introduction and know that Bill Alexander said that the Lapua brass has a "web designed for 58,000 psi" which is fine since the operating pressure is set low for good bolt life in an AR15. There are probably a number of reasons why a high-pressure Grendel is a bad idea, but my question is simply a "What If."

I wonder if someone could run a quick simulation in QuickLoad or the like?
Thanks.

[A5BLASTER]

100 to 200 fps increase.

Cut your barrels life span in half

Cases get more expensive and don't last as long

Pripretory just about everything from bolt material too barrel material and surface treatments.

Might be worth it.

Not in my book but I wouldn't stand in the way of the community having what they want.

[mel]

10k more would basically just be a 6.5 creedmoor at that point wouldnt it

[A5BLASTER]

10k more would basically just be a 6.5 creedmoor at that point wouldnt it

Yep.

[Happy2Shoot]

I thought the weak link was the ar15 sized bolt not the brass. If you want high pressure you would need something like the CMMG Mutant. I believe it has a larger bolt.

[A5BLASTER]

I thought the weak link was the ar15 sized bolt not the brass. If you want high pressure you would need something like the CMMG Mutant. I believe it has a larger bolt.

And a longer magwell to allow for a mag that allows 2.400 coal min, so one could get enough powder in the case to get it too 62k.

[Gtscotty]

10k more would basically just be a 6.5 creedmoor at that point wouldnt it

Nope, the Creedmoor is already loaded to the 62ksi that represents 10ksi higher than the Grendel, and it has far more powder capacity, and far less oal restriction. When I was playing around with Quickload after the .277 Fury announcement, I mocked up a high pressure Grendel to see what a rev'd out version would do. The gains weren't as much as you'd guess because with the volume limitations of the tiny case, you just couldn't fit enough of most of the good powders in to get great velocities with the really high pressures. Still, I think with some powders you could theoretically get close to lower end Creedmoor loads at like 90ksi-100ksi, roughly the same pressures as the .mil version of the .277 Fury, and nearly twice the pressure of the Grendel.

[lazyengineer]

Nope, the Creedmoor is already loaded to the 62ksi that represents 10ksi higher than the Grendel, and it has far more powder capacity, and far less oal restriction. When I was playing around with Quickload after the .277 Fury announcement, I mocked up a high pressure Grendel to see what a rev'd out version would do. The gains weren't as much as you'd guess because with the volume limitations of the tiny case, you just couldn't fit enough of most of the good powders in to get great velocities with the really high pressures. Still, I think with some powders you could theoretically get close to lower end Creedmoor loads at like 90ksi-100ksi, roughly the same pressures as the .mil version of the .277 Fury, and nearly twice the pressure of the Grendel.

Yea that makes sense.

[kmon]

Yup, we generally keep the Grendel to about 50,000 PSI and Some do load to the 52,800 max Grendel pressure. Boltaction some guys load to 58,000 or 60,000 and get up to about 200fps more but at the cost of less brass and barrel life. I thought about that and if I want more speed in the 264 diameter bullets I just pickup the 6.5-284 or 264 WM.


To me he Grendel itself is a great cartridge that fits it's niche very well, enough gun for a lot of my hunting and target uses with very low recoil.

I no longer have the place to shoot 800+ yards when ever I want to, that lease got sold. Now having 300 yards as my max range anywhere close and hunting wise 225 yards is my longest possible shot and most are less than 100 yards. I so not see a need for this one and several of the guns I own

[Klem]

Fess,

You will rattle your fragile AR15 to pieces. Maybe not on the first shot but whatever parts life you had, it's going to be less.

The Grendel already represents the max limit for an AR15 so why push it even further? And for what?

[Fess]

Fess,

You will rattle your fragile AR15 to pieces. Maybe not on the first shot but whatever parts life you had, it's going to be less.

The Grendel already represents the max limit for an AR15 so why push it even further? And for what?

I mainly wanted to see the tradeoff between pressure and velocity. 10K psi would get it around Creedmoor pressure, but with less powder. I wondered how much difference the lower capacity would make.

I figured that at a minimum, the bolt and barrel extension would need to be stronger, like with the CMMG mutant or Colt CK901. Weight would start to go up, of course. It's not the silliest idea, though. Remember the Olympic Arms "sorta-AR15's" that shot the WSSM cartridges?

[Klem]

Quickload says, using a 123SST you'll get an extra 125fps for the extra 10K lbs. You might need to choose a faster powder to be able to get enough in for the extra 10K and not exceed 103% which is when it starts to get seriously compressed.

There will be some guys here who are already loading above 52K lbs and either don't know it, or have an idea but think it's worth it.

[Fess]

Thanks.

Seeing the threads about bulged cases over the years, it is clear that some people have managed to accidentally get loads over 60,000 psi. :eek: The problem is that they didn't know the exact pressure.

I remember a discussion with someone on the forum about a group of people complaining about broken bolts. He said that the problem was that those guys were determined to load to over 60K, yet shocked that their AR's couldn't handle it.

[LRRPF52]

The benefits of 6.5 Grendel come from a combination of:

Lower working pressure
Mild muzzle blast
Low recoil
Substantial projectile weights
Excellent chamber and barrel life
Fits in the AR15
Excellent brass life
Low recoil and mild muzzle blast make it pleasant and easy to see what you're shooting throughout the shot. This is really the best thing about it, combined with projectile weights that do more work on-target.


Just changing the working pressure even into magnum territory of 65,000psi takes away all of those things.

AR15 barrel extension teeth aren't strong enough for more than 55,000psi with fatter cartridges than 5.56x45, so you need a new design (larger) to harness anything bigger than that or use expensive exotic alloys like AerMet.

Once you jump to a 60,000psi Grendel and projectiles 120gr and higher, sight picture management starts to get away from you. It will still be more manageable than a .308 Win, but not as pussycat as a Grendel. 80,000psi would have some significant initial recoil impulse and make sight picture like a .308 or worse.

Would need exotic alloy$ for barrel liner$ like machine-gun$.

The CT ammo has me the most interested since it reduces ammunition bulk in the COL dimensions.

None of us will be reloading for any of this, so this is best left for the Military topics forum.