Grendel and 5R Rifling (Haters gonna Hate)

[Ridgerider]

My 24" Satern cut rifled 5R barrel gets normal velocities. So I am leaning toward the tight bore theory to explain the AR Stoner results, not because of the 5R rifling.

Think you will find your Saturn barrel is a cut rifled 5 groove barrel and not 5 R rifling. It will be marked 5R on the barrel if it is.

[rickOshay]

Here's the stamp on my Satern barrel:

[Nukes]

...AR Stoner barrels are the Midwayusa brand and are made by liberty barrels and come with 5R button rifling.

Our Grendel has a Krieger 1-8.5" 5R.

[joker31]

bill saturn i thought the owner of Satern was Steve Satern?

Actually the owner is Deb Satern, Steven's Wife. I know almost everyone at the company, talked to deb last week.

And not all Satern's are marked with the specs, Mine is a custom 1 off and is only marked with Satern and a serial number on underside and 6.5 Grendel 1-8.75 on top But the Machinist Print I have says 1-8.75 5R Cut Rifling.

I was always told that the reason a 5R barrel is a little "Faster" is because the bullet seals a little better due to the unopposed Lands. (Lands are 180deg from grooves, not half land half groove like in 4 twist barrels) at least thats what it said in my Forensics text book, it said that the reason its superior and used by Marksmen is due to the fact that it seals the bullet without deforming the core like conventional rifling. Or something like that. Will look for my text book if anyone really cares. Was a class in Applied Forensic Ballistics. Basically how to recreate the origin of projectiles from very far away. now I guess they use computer models.

[kamrr4437]

Well they are married so both own the company lol. But yes you are correct Deb is the owner. I love there company. They make a fine product. They are good people.

[woohoo]

This conversation has been spread out over a couple threads so i decided to consolidate the conversation. To sum up 5R rifling is providing higher velocities with the grendel. 5R rifling doen't have the 90 degree angles which means higher velocities and less copper fouling.





Hornady 123 Amax measured from my and a friends 24in AR-Stoner barrels has a MV of 2650fps vs 2580fps quoted by Hornady. Out of my 18in AR Stoner i'm getting 2560fps. Thats about what you would expect from a typical Grendel with a 22in barrel.

[video=youtube;49GsxciNPUc]http://www.youtube.com/watch?v=49GsxciNPUc&feature=youtu.be[/video]

One of the main criticisms of the Grendel usually levied by the 6.8SPC crowd is lower MV but as you see the 5R rifling gives the Grendel at least a 80fps boost. Now you can both get good muzzle velocities and long legs and good accuracy. The faster the load the more performance boost you'll notice. When your shooting the lower grain pills like the 100gr and 95gr fast you can see as much a 150fps boost. I've cronyed 3 AR Stoner rifles now with factory Amax and all three are shooting much faster than other Grendels with the same ammo. 6.5mm pills are longer and have larger surface area that contacts the rifling. Therefore 5R rifling is going to benefit the Grendel more so than shorter fatter calibers like the 6.8SPC.

AR Stoner barrels are the Midwayusa brand and are made by liberty barrels and come with 5R button rifling.

What load are you using to push a 123 to 2650fps out of a 16" barrel?
The photo of the button you posted is really a Hybrid 5R like we use. An Obermyer or Rock has a different land shape, angled but different than shown.
On the same page you took that photo from but further down the page-
.
I have not bore scoped a Satern to see if it is like the Obermyer or if it is a Hybrid. There were posts on the old Grendel forum as far back as 2007 showing the velocities possible with 5R barrels but it is more than just the shape. Bore area, groove diameter and land to groove ratio all play a part in accuracy, pressure produced and velocity. Tweaking all of those can get you a barrel that is much faster but not so accurate or super accurate and a little higher pressure, just depends on what is more important to the person designing the button.
Maybe Bill A. can chime in but it looked to me like the less expensive AA barrels may be a 6R. I didn't spend a lot of time with it or video it but through the borescope the lands looked like they had sloped sides.
These are MAX loads in my 264 5R barrel with a .100 freebore. Some of the max loads shoot 1 MOA easy enough if that is good enough to hunt with. To find 1/2 MOA most need to be dropped 1/2 -1 gr.

123AM 2.3 748.. 31.5 2643 CCI450 20" max charge
123AM 2.3 335.. 29.5 2672 CCI450 20" max charge
123AM 2.3 4895 29.5 2650 CCI450 20" max charge
123AM 2.3 530.. 28 2682 CCI450 20" max charge
123AM 2520 31 2660 BR ........20" max charge

[Dan]

Customer service at Satern told me that Steve doesn't do anything but 5R rifling.

[XcountryRider]

What load are you using to push a 123 to 2650fps out of a 16" barrel?
The photo of the button you posted is really a Hybrid 5R like we use. An Obermyer or Rock has a different land shape, angled but different than shown. I have not bore scoped a Satern to see if it is like the Obermyer or if it is a Hybrid. There were posts on the old Grendel forum as far back as 2007 showing the velocities possible with 5R barrels but it is more than just the shape. Bore area, groove diameter and land to groove ratio all play a part in accuracy, pressure produced and velocity. Tweaking all of those can get you a barrel that is much faster but not so accurate or super accurate and a little higher pressure, just depends on what is more important to the person designing the button.
Maybe Bill A. can chime in but it looked to me like the less expensive AA barrels may be a 6R. I didn't spend a lot of time with it or video it but through the borescope the lands looked like they had sloped sides.
These are MAX loads in my 264 5R barrel with a .100 freebore. Some of the max loads shoot 1 MOA easy enough if that is good enough to hunt with. To find 1/2 MOA most need to be dropped 1/2 -1 gr.

123AM 2.3 748.. 31.5 2643 CCI450 20" max charge
123AM 2.3 335.. 29.5 2672 CCI450 20" max charge
123AM 2.3 4895 29.5 2650 CCI450 20" max charge
123AM 2.3 530.. 28 2682 CCI450 20" max charge
123AM 2520 31 2660 BR ........20" max charge

You missed something those are factory Amax out of 24in barrels.

[woohoo]

You missed something those are factory Amax out of 24in barrels.

oh, I thought you said you were getting the same velocity with handloads as they were getting with 6.8 handloads.

[XcountryRider]

oh, I thought you said you were getting the same velocity with handloads as they were getting with 6.8 handloads.

Awe no the 6.8 folks are still beating us at MV just with these AR Stoner/liberty barrels we are doing pretty decent in the MV department with 80 to 100fps more with factory ammo for the 123gr Amax. We can also get handload 140gr pills going at 2450fps as well.

[woohoo]

Awe no the 6.8 folks are still beating us at MV just with these AR Stoner/liberty barrels we are doing pretty decent in the MV department with 80 to 100fps more with factory ammo for the 123gr Amax. We can also get handload 140gr pills going at 2450fps as well.

10-4. I am a 6.8 shooter too.
The numbers I posted above are from my barrels. 1 is a Rock that I have had since 2006, the other is 1 of my 5R button barrels. Those loads are safe with CCI 450 and 41 primers and Lapua cases with the Amax loaded to 2.295" in my barrels. Those loads may not be safe in every barrel. I've been shooting some of them since 2007. They aren't piercing primers or rupturing cases or breaking bolts and I still get 10+ loads out of the cases so I know I'm ok loading and shooting those loads.
They may be too hot for some combinations.

[Tedward]

Actually the owner is Deb Satern, Steven's Wife. I know almost everyone at the company, talked to deb last week.

And not all Satern's are marked with the specs, Mine is a custom 1 off and is only marked with Satern and a serial number on underside and 6.5 Grendel 1-8.75 on top But the Machinist Print I have says 1-8.75 5R Cut Rifling.

I was always told that the reason a 5R barrel is a little "Faster" is because the bullet seals a little better due to the unopposed Lands. (Lands are 180deg from grooves, not half land half groove like in 4 twist barrels) at least thats what it said in my Forensics text book, it said that the reason its superior and used by Marksmen is due to the fact that it seals the bullet without deforming the core like conventional rifling. Or something like that. Will look for my text book if anyone really cares. Was a class in Applied Forensic Ballistics. Basically how to recreate the origin of projectiles from very far away. now I guess they use computer models.

Sounds like what I posted earlier is true about the angle of the land to barrel makes a better seal. I wasn't in class either

I missed a lot here watching the football game, and it sucked, this sounded more entertaining....

[Tedward]

I can't wait for your to get your AR Stoner (US Made) Libery barrel cronyed Tedward. We'll call it the 2650fps club those that have a barrel that can send out a factory 123 Amax at 2650 fps or above

Looks like I have a need to get croyned now more than ever so I'll get it set up with someone who I can borrow one from. Might even have to just break down and buy one....

[joker31]

Customer service at Satern told me that Steve doesn't do anything but 5R rifling.

Yep, their production manager just confirmed it for me too.

As far as the fast and less accurate or accurate and high press, it makes sense, my barrel shows pressure signs with low max loads (29gr of 2520 show press signs when AA says 30.7 is max)

[cory]

Awe no the 6.8 folks are still beating us at MV just with these AR Stoner/liberty barrels we are doing pretty decent in the MV department with 80 to 100fps more with factory ammo for the 123gr Amax. We can also get handload 140gr pills going at 2450fps as well.

By just how much velocity are they beating us? What is 6.8 average velocity for a 130gr projectile from a ~20" barrel?

To do a fair comparison to the Grendel 123gr bullet I believe we need to use a 6.8 130gr bullet.

This is how I came about that.

6.8 Comparison Projectile(gr) = (Grendel Projectile(gr)/6.5(mm))*6.8(mm)

[LRRPF52]

The best comparison is if you can find a factory load from one company, that uses the same bullet construction/type, and same bullet weight. The 6.5 Grendel 123gr SST and 6.8 SPC 120gr SST factory loads are a great comparison from 16" barrels.

Hornady lists 16" 6.5 Grendel velocity from their 14.5" barrel with permanently attached muzzle device, which they used for the 8th Edition Grendel loads. They list 16" MV at 2350fps on their site.

My 16" AA Grendel gets 2460fps with the 123gr factory load. That is the exact same velocity posted for the 120gr SST 6.8 from a 16" barrel.

At the end of the day, you're looking at a .510 BC vs. a .400 BC. Even the 14.5" Grendel fares well against the 18" 6.8 with those BC's.

[woohoo]

By just how much velocity are they beating us? What is 6.8 average velocity for a 130gr projectile from a ~20" barrel?

To do a fair comparison to the Grendel 123gr bullet I believe we need to use a 6.8 130gr bullet.

This is how I came about that.

6.8 Comparison Projectile(gr) = (Grendel Projectile(gr)/6.5(mm))*6.8(mm)

It would be nice to make the numbers look better if you use a heavier bullet in the faster rifle and a lighter one in the slower one but if you use the same weight bullets out of the same length and type barrels both handloaded to max safe levels the 6.8 consistently produces apx 100fps more than the 264/Grendel. Factory ammo pressures are all over the map from 45k psi to 55k PSI but if that is all one shoots then that is what should be compared.
Figure thrust on the bullet to understand why there is some improvement with a larger bore. Area of a .264 bullet VS area of a .277 bullet just like guys here figure thrust on the bolts because the G case is larger dia. The larger dia bore allows the use of faster burning powders, the extra thrust and shorter bullets creating less resistance =more velocity.
I've been shooting both with the same 5R rifling since 2007 side by side using the same method to determine max loads.
Out to 300yds both are very close, after that the higher BCs of the .264 bullets help keep the velocity up making it a better long range target round.

[woohoo]

The best comparison is if you can find a factory load from one company, that uses the same bullet construction/type, and same bullet weight. The 6.5 Grendel 123gr SST and 6.8 SPC 120gr SST factory loads are a great comparison from 16" barrels.

Hornady lists 16" 6.5 Grendel velocity from their 14.5" barrel with permanently attached muzzle device, which they used for the 8th Edition Grendel loads. They list 16" MV at 2350fps on their site.

My 16" AA Grendel gets 2460fps with the 123gr factory load. That is the exact same velocity posted for the 120gr SST 6.8 from a 16" barrel.

At the end of the day, you're looking at a .510 BC vs. a .400 BC. Even the 14.5" Grendel fares well against the 18" 6.8 with those BC's.

So you are comparing your barrel vel to a vel posted by Hornady to be the same? Why not just use the vel posted by Hornady for both cartridges that seems a little more accurate and fair. They post 2350 for a 6.5 -123 SST and 2460 from a 6.8 120 SST both from 16"barrels..

[cory]

It would be nice to make the numbers look better if you use a heavier bullet in the faster rifle and a lighter one in the slower one but if you use the same weight bullets out of the same length and type barrels both handloaded to max safe levels the 6.8 consistently produces apx 100fps more than the 264/Grendel...

Negative. It's not nice it's necessary for a true analysis.

You wouldn't use a 123gr 308 projectile to compare it to the Grendel would you?

For the very reasons you stated you have to take in account projectile diameter with its weight to make a true comparison. The 6.8 is a larger bore rifle compared to the Grendel, so when comparing MV appropriate projectiles should be used.

LRRPF52 as those are the two projectiles Hornady produces for the two chambers it's a good comparison.

However, to compare the ability and potential of the two rifles a linear comparison needs to be made. I'd also suggest that it's done with a variety of comparisons.

i.e. 6.8 vs 6.5
130gr to 123gr
120gr to 115gr
115gr to 110gr

Note: I'm not hear trying to prove the Grendel is superior to the 6.8 in every way under the sun. The 6.8 is a good rifle. I just want to see the correct comparison made.

As long as we're talking in facts and analysis based in mathematics and science I'm happy.

[woohoo]

Negative. It's not nice it's necessary for a true analysis.

You wouldn't use a 123gr 308 projectile to compare it to the Grendel would you?

For the very reasons you stated you have to take in account projectile diameter with its weight to make a true comparison. The 6.8 is a larger bore rifle compared to the Grendel, so when comparing MV appropriate projectiles should be used.

LRRPF52 as those are the two projectiles Hornady produces for the two chambers it's a good comparison.

However, to compare the ability and potential of the two rifles a linear comparison needs to be made. I'd also suggest that it's done with a variety of comparisons.

i.e. 6.8 vs 6.5
130gr to 123gr
120gr to 115gr
115gr to 110gr

Note: I'm not hear trying to prove the Grendel is superior to the 6.8 in every way under the sun. The 6.8 is a good rifle. I just want to see the correct comparison made.

As long as we're talking in facts and analysis based in mathematics and science I'm happy.

I'll bet I can throw cat further than you can throw a cow. Both have 3 letters, start with a C and have 1 vowel, they're similar so lets compare.