Grendel II chamber

[bwaites]

So it sounds like the GII is no worse or better than the Grendel chamber, and similar to LBC. So why all the uproar? If it was "I bought a barrel expecting X chamber and received Y" I get that.

Other than that, i dont see the issue. Am I missing something?

The 6.5 caliber has a huge range of bullets available, all the way from 85 grain varmint bullets to 160 grain round nose bullets. AR's are almost unique in that they can be extremely accurate, but are gas operated. To find a chamber that would allow the tolerances necessary for semi-auto action (or even full auto!) and still be extremely accurate was the challenge. Bill Alexander ran into accuracy issues trying to make a wide variety of bullets work, until it was suggested that some of the older military chambers had a compound throat and seemed to shoot a variety of bullets well. That compound throat angle apparently centered the bullet, allowing improved accuracy from a chamber that was otherwise tolerant of the necessities of gas operation. The compound throat was developed for the Grendel and by all accounts solved the problem that they had run into with that wide range of bullets. At one point I was able to shoot every factory load, from 90 grain varmint bullets to 130 grain hunting bullets, into sub MOA groups from my first Grendel. That is extremely rare, and led me to believe that Alexander had indeed succeeded. Others have found similar results.

I was able to shoot 2 different handloads into .25 MOA groups with that same barrel. My current 28" Grendel will shoot the 107 Sierra into sub .25 MOA groups, with my best 5 shot group at .18 inches. It will shoot the 123 Factory Amax load sub MOA all the way out to 1000 yards. In fact, I actually shot that rifle in an F Class match at 1000 yards when my usual F Open rifle's barrel dumped on me. On a very windy day, I was the only F Class shooter (in a small field, admittedly) with X's.

You will find very few, if any, traditional chambers that will shoot bullets of such wide range in weight that well.

Given my choice, I would always pick the SAAMI chamber in a gas gun. 2nd choice would be the LBC chamber, which has proven to be accurate with more than one bullet, though it was designed around the 123 Sierra and 123 Amax. The tighter neck (.295) most likely allows for better centering of the bullet in the bore. I actually just finished running a test on a 16" barrel in that chamber and it shot the 123 AMAX well. The last I would choose would be the GII, because it gives away the tighter neck AND the centering effect of the compound throat. Comparing the 3, the I can't find a single advantage in comparison to the other 2.

[ThatRandomGuy]

So it sounds like the GII is no worse or better than the Grendel chamber, and similar to LBC. So why all the uproar? If it was "I bought a barrel expecting X chamber and received Y" I get that.

Other than that, i dont see the issue. Am I missing something?

As for the actual chamber, I believe bwaites said it best.

For the uproar, it was because a company was putting out non-SAAMI spec barrels, still calling them Grendels, and continued to even after it was shown in several cases they were not. These barrels caused issues with factory ammo (especially the 120ish grain it seemed). Said company blamed the ammo manufacture, and offered to "scrape" the barrels to a wider chamber to accept all types without issue. That scraped chamber is (to my understanding) what they now call the Grendel II. So it was basically people ordered X chamber, got Y as you said, with the main furor being how the situation was put off on others instead of accepted and fixed to the standard originally desired.

[Drifter]

...the main furor being how the situation was put off on others instead of accepted and fixed to the standard originally desired.

Yep.

[babaganoush]

Given my choice, I would always pick the SAAMI chamber in a gas gun. 2nd choice would be the LBC chamber, which has proven to be accurate with more than one bullet, though it was designed around the 123 Sierra and 123 Amax. The tighter neck (.295) most likely allows for better centering of the bullet in the bore. I actually just finished running a test on a 16" barrel in that chamber and it shot the 123 AMAX well. The last I would choose would be the GII, because it gives away the tighter neck AND the centering effect of the compound throat. Comparing the 3, the I can't find a single advantage in comparison to the other 2.

I agree, for the most part, Bill. Where the Grendel opted for a compound throat to keep (all) bullets better aligned to the bore, the LBC went to a slightly tighter throat to aid in bullet alignment. This reminded me of something I read in the not too distant past.

The throat of a rifle barrel is often an overlooked part of the chamber. The throat, however, is very important, especially as related to accuracy. The bullet engages the rifling in the throat. It's critical that the bullet make the transition from case neck to rifling without losing its axial alignment. It's possible for a bullet that is concentric with the bore while in the case neck to enter the barrel misaligned because of a sloppy throat. An oversized throat can allow the bullet to become distorted or canted as it enters the rifling. As a result the bullet will not be spinning around its center of form and has yaw while still in the barrel. When the bullet leaves the muzzle it will yaw even more, causing greater dispersion on the target than would otherwise be seen.

This information, not surprisingly, is found on one of the country's most respected barrel maker's site, Lilja Precision.

http://www.riflebarrels.com/articles/50calibre/throats_50_bmg.htm

While written in the context of the 50, the fundamentals are the same.

Where I disagree with you is on the cause/effect relationship between the chamber and case neck. While I acknowledge your use of the words "most likely", I believe that without the Grendel's compound throat, it is more likely the case shoulders which provide bore alignment. The tighter throat will allow less deformation or off-axis movement on the part of the bullet.

The other benefit to the LBC's tighter neck is that the brass is worked less during resizing, though not a concern to those who shoot factory ammo, exclusively.

So, either way you look at it, the LBC has the potential to be more accurate than a similar chamber with a sloppier neck, the Grendel and its compound throat not withstanding.

[cory]

So it sounds like the GII is no worse or better than the Grendel chamber, and similar to LBC. So why all the uproar? If it was "I bought a barrel expecting X chamber and received Y" I get that.

Other than that, i dont see the issue. Am I missing something?

To put it simply, a company was producing non SAAMI barrels and advertising them as SAAMI spec Grendels.

Now for the kicker. It was found that some of these barrels were potentially catastrophically hazardous to the user. When the company became aware of this, they denied all fault and blamed the ammunition manufacturers. (Hell if the POTUS can just blame someone else then why can't they?)

Per MIL-STD-882E
Catastrophic: Could result in one or more of the following: death, permanent total disability, irreversible significant environmental impact, or monetary loss equal to or exceeding $10M.

[tango29]

Good deal, wave, and that's what it's all about! Hope the rest can finally move on as well.

John

Amen to that. It is getting old. We as group have in my estimation proffered at least 1000
posts on this topic and all we have done is agreed to do disagree. My suggestion is to only
deal with ethical companies that supply exactly what you ordered and are expecting.


Let the buyer beware.


Lets hope people can move forward and discuss other more interesting aspects of the Grendel. We have beat this topic to death. May I suggest the moderator lock any
current and future posts that refer to the bad throats. This topic is making me throw up.




Just my .02 worth

[NugginFutz]

Lock this thread! Lock this thread! Attica! Attica!

[tango29]

Lock this thread! Lock this thread! Attica! Attica!

10-4 Good buddy.

[LR1955]

OK Guys:

Enough of this one for now. I will see Bill Waites tonight and if he wants to unlock the thread, he can.

LR1955