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.