AR-Stoner 6.5 Grendel barrel short chambered.

[XcountryRider]

So, this may not be internet hysteria? Maybe steps should be taken to assure this internet hysteria doesn't effect the ongoing 20 in fluted Liberty group barrel buy.

Any comments to my question posed in post number 185, about manually inserting a bolt without the carrier in an uninstalled barrel? Is this a flawed method? If not, then those with barrels awaiting parts can get a clue if their barrel has internet hysteria.

A factory round was never inserted. He is using estimates not actual rounds. Keep the hysteria rolling.

[cory]

A factory round was never inserted. He is using estimates not actual rounds. Keep the hysteria rolling.

Measuring with a Hornady OAL gauge is not an estimate. It may not have tight tolerances, but it's relatively accurate for our needs here.

Manually inserting a round with bolt isn't an estimate. It's a yes/no. Is there lands marks or not.

[XcountryRider]

The barrel isn't even installed on the upper. It's not even broken in or fired.

[LRRPF52]

After talking to Satern yesterday, he also said the Grendel was designed around lighter weight bullets, 108gr to 120gr, so since things have changed in bullet development over the years, the Grendel Chamber and throat haven't.

Also the 120gr GMX has 2 cannelure's so you can seat deep or shallow.
http://www.hornady.com/store/6.5mm-.264-120-gr-GMX/

If they feel the throat might have a little less OAL with the bullet they are testing with, try using the A-max might be better to start with since it doesn't have the cannelure, try a lower grain like some 100 gr and see if that helps the OAL issue. Then check the OAL with the 123gr and if allowable, go to longer heavier bullets.

Again, if someone doesn't hand load and is having issues with factory Hornady ammo, send the barrel in question to Satern with the ammo so they can see the issue.

The Grendel was designed to handle a wide range of projectile weights. Most of the production ammunition has been 120gr or higher, dating back for years.

120gr NBT
129gr SST
130gr Swift Scirocco
123gr Lapua Scenar (This was the main bullet referenced in many of the comparisons against 77gr 5.56 and M118 7.62 NATO dating back at least a decade now.)

Then PPU started cranking out 123gr SP and 120gr MPT loads.

Lighter bullets have been the rare exceptions, not the norm with the Grendel. Only lightweight factory load I can think of is the 90gr TNT, which was discontinued.

As to the GMX, it doesn't have any cannelures, being a solid projectile. It has driving bands, which also help reduce large for weight bearing surface on the monoliths, and this is common with solid copper units. They help keep the start pressure down to a manageable level, which is still higher than cup & core bullets.

[LRRPF52]

The barrel isn't even installed on the upper. It's not even broken in or fired.

The barrel does not need to be installed in the upper to determine maximum allowable COL with a bullet, since the AR15 barrel extension is already installed.

[adrenaline junkie]

The barrel isn't even installed on the upper. It's not even broken in or fired.

this isn't a trigger, or a charging handle being talked about, you don't just "shoot it out" or break it in if its got tolerance problems. that's dangerous and just plain stupid. There's a reason for checking tolerances before firing, no one wants a dangerous situation. Thats a small explosion happening an inch or two from your face....

There may be a bit if hysteria happening until this is researched and measured more, but there's also some burying your head in the sand over this issue as well.

[dmsims21]

I don't think the GMX an TTSX have cannelurs. They are banded solids. The bands are to reduce start pressure and/or reduce fouling.

[Sputnik]

He is using estimates not actual rounds. Keep the hysteria rolling.

And mine? Please comment on post #185. XCR, Nobody is blaming anyone for anything here. All we seek are answers, so we can't discount or avoid the questions.

All I have shot so far in my PF Grendel is 123 Amax and 123 SST. Some Factory some reloads trying to duplicate factory measurements. All I intend to shoot presently, are these type rounds. I want to do it safely and with the confidence something bad should not happen. Is it not ok to try to get questionable issues resolved, without being accused of hysteria? Is that not what we are all about here?

[Tedward]

The Grendel was designed to handle a wide range of projectile weights. Most of the production ammunition has been 120gr or higher, dating back for years.

120gr NBT
129gr SST
130gr Swift Scirocco
123gr Lapua Scenar (This was the main bullet referenced in many of the comparisons against 77gr 5.56 and M118 7.62 NATO dating back at least a decade now.)

Then PPU started cranking out 123gr SP and 120gr MPT loads.

Lighter bullets have been the rare exceptions, not the norm with the Grendel. Only lightweight factory load I can think of is the 90gr TNT, which was discontinued.

As to the GMX, it doesn't have any cannelures, being a solid projectile. It has driving bands, which also help reduce large for weight bearing surface on the monoliths, and this is common with solid copper units. They help keep the start pressure down to a manageable level, which is still higher than cup & core bullets.

OK, I just passed along what was said to me.

As for the rings, bands or what ever they are called, thanks for clearing that up.

[woohoo]

Another way of putting this, is that SAAMI certification gave a standard that both rifle makers and ammunition makers must adhere to for a particular cartridge.

BUT!!. If you look at the SAAMI prints many of them show the max ammo size can be larger than the minimum chamber size. Hornady is producing ammo larger than the minimum chamber size. The go gauge passes but the ammo will not fit in the chamber.
SAAMI, if they ARE the standard setting organization should change their number to correct that. If I was making ammo I would make sure the ammo is .001 under the minimum chamber size or "go"gauge.

Look real close at the SAAMI grendel chamber print, there is no freebore. .2644 to .2617 in .153" directly in front of the case and cone.
The cone is .017" long, after that should be a freebore .264- .2645 in dia. In the Grendel where the normal freebore would start the throat starts, gets smaller from .2644 to .2617 in .153" then changes angle to 1.5 degree.
If any part of the bullet sticking out of the case is .264 dia it will hit the sides of the compound throat. ED-explained below
Edited for more accurate explanation. If we calc out the angle of the .2644-.2617 area the point where that area becomes smaller than the bullet dia is .0226 in front of the cone or 1.5498" from the base. If the dia of any bullet is .264" and in front of 1.5498 it will be jammed into the lands or in this case the compound throat.
After checking the Hornady 123 Amax ammo I'm betting the bullets will scuff in every Grendel chamber not just the Satern chambers. Color the bullets with a sharpie and chamber them.

[JASmith]

BUT!!. If you look at the SAAMI prints many of them show the max ammo size can be larger than the minimum chamber size. Hornady is producing ammo larger than the minimum chamber size. The go gauge passes but the ammo will not fit in the chamber.
SAAMI, if they ARE the standard setting organization should change their number to correct that. If I was making ammo I would make sure the ammo is .001 under the minimum chamber size or "go"gauge.

Look real close at the SAAMI grendel chamber print, there is no freebore. .2644 to .2617 in .153" directly in front of the case and cone.
The cone is .017" long, after that should be a freebore .264- .2645 in dia. In the Grendel where the normal freebore would start the throat starts, gets smaller from .2644 to .2617 in .153" then changes angle to 1.5 degree.
If any part of the bullet sticking out of the case is .264 dia it will hit the sides of the compound throat. ED-explained below
Edited for more accurate explanation. If we calc out the angle of the .2644-.2617 area the point where that area becomes smaller than the bullet dia is .0226 in front of the cone or 1.5498" from the base. If the dia of any bullet is .264" and in front of 1.5498 it will be jammed into the lands or in this case the compound throat.

First, let's confine our discussion to the SAAMI print for the Grendel (http://www.65grendel.com/forum/showthrea...ink-*here*). Please tell us were a maximum cartridge is larger than a minimum chamber.

The "Go Gauge" registers the distance between a specified radius on the shoulder and the bolt face. One can have a solid shank drilled to that dimension and only steel starting at the neck-shoulder junction and the "Go" gauge will fit, but even an empty cartridge will not.

Excellent points about how what is normally described as the freebore. The discussion on page 8 in Volume 1 of the 6.5 Grendel Reloading Handbook tells us why this why this feature exists. The feature is part of the "secret sauce" that balances superb accuracy with reliable function in the AR. The throat configuration also helps explain why some factory ammunition is loaded with a shorter COL than would be suggested by the magazine dimensions.

[JASmith]

I have looked closely at the Grendel throat configuration on several occasions. I have also followed the controversies swirling around it and do have a feel why some believe the Grendel neck should be tighter for accuracy purposes. The taper Woohoo observes is part of why the .300" chamber neck works and allows Grendel shooters to get the superb accuracy we see.

I believe that part of the the reason some reamer makers are at odds with the Grendel spec is that they have not yet taken the time to understand this subtlety and try tweak their reamer to their vision of the "right way" to do things. I will add that the tweaking is reasonable when one is dealing with wildcat cartridges because that is what wildcats are about.

Messing with an industry standard, however, can lead to disaster for all concerned.

This thread is an example.

On the bright side, it appears that Satern is taking a closer look at their chambers and it will be some time before their trouble shoot exercise is completed. We may have reached the point where everyone should take a break, read the pertinent chapters in the handbook, do more research in other sources and do their own analyses. If at that point, we still seem to have issues, let's start a fresh thread!

[woohoo]

First, let's confine our discussion to the SAAMI print for the Grendel (http://www.65grendel.com/forum/showthrea...ink-*here*). Please tell us were a maximum cartridge is larger than a minimum chamber.

The "Go Gauge" registers the distance between a specified radius on the shoulder and the bolt face. One can have a solid shank drilled to that dimension and only steel starting at the neck-shoulder junction and the "Go" gauge will fit, but even an empty cartridge will not.

Excellent points about how what is normally described as the freebore. The discussion on page 8 in Volume 1 of the 6.5 Grendel Reloading Handbook tells us why this why this feature exists. The feature is part of the "secret sauce" that balances superb accuracy with reliable function in the AR. The throat configuration also helps explain why some factory ammunition is loaded with a shorter COL than would be suggested by the magazine dimensions.

Notice I said some...like the 223, 308, 6.8 and several others. The Grendel SAAMI spec is correct. 1.220 is the max ammo size and 1.220 is the min chamber size.

Maybe Hornady and everyone else should load their 123Amax a little shorter to keep it out of the lands. The ammo I have is loaded to 2.252". Using a hole gauge it appears the bullets would scuff or jam the lands in a Grendel chamber.

My 6.5 Banshee chamber from 07 is almost identical to the 264LBC chamber. It has a true freebore .264 in dia .091 long, .103 when combined with the cone length. I can load the 123 Amax to 2.295 and end up .010 off the lands.

Just to be clear about what I am saying, there may not be anything wrong with the Liberty barrels. IMO all bullets except the VLDs need to be loaded to keep them off the lands.

[JASmith]

...The Grendel SAAMI spec is correct. 1.220 is the max ammo size and 1.220 is the min chamber size.

....The ammo I have is loaded to 2.252". Using a hole gauge it appears the bullets would scuff or jam the lands in a Grendel chamber

My 6.5 Banshee chamber from 07 is almost identical to the 264LBC chamber. It has a true freebore .264 in dia .091 long, .103 when combined with the cone length. I can load the 123 Amax to 2.295 and end up .010 off the lands.

Are we looking at the same drawing? The SAAMI drawing in the link (http://www.65grendel.com/forum/showthrea...ink-*here*) has NO max cartridge length shown for the chamber and the cartridge drawing specifies a minimum length of 2.135" and a maximum length of 2.260"

Your ammunition length of 2.52" is within specifications.

6.5 Banshee and .264 LBC? I am reasonably sure that the LBC does not conform to SAAMI spec. If the Banshee refers to a cartridge, then one could not reasonably expect it to conform to the SAAMI standard.

To reiterate post #231, it is time to go back, do our homework, think things through and to give Steve Satern a chance to trouble shoot his sources and processes.

After that, we should start a fresh thread. This one is already too long, too jumbled, and too full of hype for a reasonable person to read through.

[woohoo]

Are we looking at the same drawing? The SAAMI drawing in the link (http://www.65grendel.com/forum/showthrea...ink-*here*) has NO max cartridge length shown for the chamber and the cartridge drawing specifies a minimum length of 2.135" and a maximum length of 2.260"

Your ammunition length of 2.52" is within specifications.

6.5 Banshee and .264 LBC? I am reasonably sure that the LBC does not conform to SAAMI spec. If the Banshee refers to a cartridge, then one could not reasonably expect it to conform to the SAAMI standard.

To reiterate post #231, it is time to go back, do our homework, think things through and to give Steve Satern a chance to trouble shoot his sources and processes.

After that, we should start a fresh thread. This one is already too long, too jumbled, and too full of hype for a reasonable person to read through.

I didn't say anything about 2.25 not being in spec I said it looks like it will jam the lands at that length. Both the 264LBC and 6.5 Banshee were designed before the Grendel was SAAMI so yep I agree neither conform to the SAAMI spec. and both allow loading longer than 2.26"

[JASmith]

I didn't say anything about 2.25 not being in spec I said it looks like it will jam the threads at that length. Both the 264LBC and 6.5 Banshee were designed before the Grendel was SAAMI so yep I agree neither conform to the SAAMI spec. and both allow loading longer than 2.26"

We have lost track of the point of the thread. We know that factory Grendel ammunition works fine in Grendel-stamped barrels. The few exceptions happen when one or both are out of spec.

Next topic?

[LRRPF52]

I just went and double-checked my known AA SAAMI chamber, and a box of 123gr Hornady SST factory ammunition, as well as my 123gr A-MAX hand loads that are at 2.272"-2.275" COL.

With the 123gr SST's, raw COL comes out to 2.232" to 2.240". How much of that is polymer meplat vs. ogive and seating depth variation, who knows.

I blackened my ogive just above the cannelure, dropped a loaded factory 123gr SST in my chamber with the upper receiver oriented vertically, and removed the case. I repeated this several times. I was able to barely detect the slightest hint of engagement with the cone in the Grendel chamber, but we're talking just the ever-so-slightest kiss.

I then grabbed my 123gr A-MAX hand loads that are at 2.272" COL, and there was little, if any forcing cone kiss. We are nowhere near the actual lands, but are at the hand-off point for the forcing cone, where the angle begins. From a physics standpoint, this very slight angle accomplishes a few things.

Regarding pressure, you have a nice transition from the release out of the neck tension, right into a uniform bearing surface, rather than a jump.

For a gas gun with magazine OAL and reliability considerations, the forcing cone makes a lot of sense. One of the biggest complaints you will see with factory gas guns that people are using to chase accuracy, is that there is too much jump to the lands from even the maximum magazine allowable OAL. No such problem with the SAAMI Grendel chamber. Combined with the .300" neck in the chamber, which allows for reliable chambering in even adverse conditions with a gasser, the forcing cone handles a wide range of projectiles well.

The forcing cone also centers the projectile, regardless of how it is oriented in the cartridge & chamber. Most accuracy seekers approach this issue with a tighter neck, but that isn't the best method in a self-loader, as I have learned with my .260 Rem AR10. Only way I can load and shoot factory brass is if I size all the brass before loading. The Grendel is much more forgiving in this regard.

[woohoo]

Most accuracy seekers approach this issue with a tighter neck, but that isn't the best method in a self-loader, as I have learned with my .260 Rem AR10.

No one I know tries to align the bullet on the bore using the neck dia in the chamber. They make the chamber neck smaller so the brass last longer.
They turn necks so the necks are consistent then they make the neck smaller to make the brass last longer.
The freebore is made bullet dia to align the bullets on the bore. That way when using factory ammo all bullets are aligned by the outside full diameter of the bullet. When using the lands to center the bullet the bullets must be loaded very close to the exact location to touch the lands. If they aren't touching the lands the bullet is not centered on the bore.

[Lead Chucker]

I used a 123gn Amax bullet, a dowel rod and 2 rod stops. I measued my Satern chamber from bolt face to where the bullet touched the lands, i got 2.200". I then used the same bullet & did the same with my dads new 16" Stoner barrel. I got 2.188 with it. I have 300+ rounds down mine & 0 down his. Thats .012" difference. Would you send it back or tr it out. I have bern reloading most of my life & have many rifles that have never had a factory round shot through them. I know i can reload for this barrel & after shooting it will smooth out & probably improve the OAL. So would you keep & shoot it or send it back to Midway?

[Tedward]

I just went and double-checked my known AA SAAMI chamber, and a box of 123gr Hornady SST factory ammunition, as well as my 123gr A-MAX hand loads that are at 2.272"-2.275" COL.

With the 123gr SST's, raw COL comes out to 2.232" to 2.240". How much of that is polymer meplat vs. ogive and seating depth variation, who knows.

I blackened my ogive just above the cannelure, dropped a loaded factory 123gr SST in my chamber with the upper receiver oriented vertically, and removed the case. I repeated this several times. I was able to barely detect the slightest hint of engagement with the cone in the Grendel chamber, but we're talking just the ever-so-slightest kiss.

I then grabbed my 123gr A-MAX hand loads that are at 2.272" COL, and there was little, if any forcing cone kiss. We are nowhere near the actual lands, but are at the hand-off point for the forcing cone, where the angle begins. From a physics standpoint, this very slight angle accomplishes a few things.

Regarding pressure, you have a nice transition from the release out of the neck tension, right into a uniform bearing surface, rather than a jump.

For a gas gun with magazine OAL and reliability considerations, the forcing cone makes a lot of sense. One of the biggest complaints you will see with factory gas guns that people are using to chase accuracy, is that there is too much jump to the lands from even the maximum magazine allowable OAL. No such problem with the SAAMI Grendel chamber. Combined with the .300" neck in the chamber, which allows for reliable chambering in even adverse conditions with a gasser, the forcing cone handles a wide range of projectiles well.

The forcing cone also centers the projectile, regardless of how it is oriented in the cartridge & chamber. Most accuracy seekers approach this issue with a tighter neck, but that isn't the best method in a self-loader, as I have learned with my .260 Rem AR10. Only way I can load and shoot factory brass is if I size all the brass before loading. The Grendel is much more forgiving in this regard.

Is that a brand new unfired AA barrel? If not is it possible it was more than a kiss on the first date. After being fired "X' numbers of times your virgin barrel might not be as tight after the first load was let loose. Use the barrel and see how it is. If it wont chamber with factory ammo, send it back for investigation. And no it wont just slip right in the first time, it will need a little finesse or thrust.

As J.A. Smith said, sit back and look at the info. I have looked at the drawing for hours and discussed with many people in depth. Read the numbers of the throat. Right under the case end measurement (.2644) is shows the next measurement of the free-bore ( .2617). That is a smaller number than .264 so it will touch, kiss, a .264 diameter bullet.