02-14-2014, 04:28 PM
woohoo Wrote:This is a description by Sputnik in post #17-" By looking into the chamber, it appears they scraped/removed all or part of the compound throat as I see a small "ring" around the throat just before the lands begin; where it looks like it was removed or slightly "bored out""
This is your reply-
Sputnik,
From all that has been said, it appears that your velocities and especially your pressures will most likely be in line with the norms expected of factory ammunition.
The ring you observed is troubling in that there is no feature described in the SAAMI drawing that would evoke a feature like that. Furthermore, I am told that the way to fix a tight chamber is to run a finishing reamer through it. That operation should not produce the ring you describe.
Regarding accuracy, you probably will find acceptable woodland hunting accuracy with some bullets. Chances are the rifle will like one or two a lot more than others.
We know from Chapter 8 of Volume 1 of the Grendel Reloading handbook that the compound throat was developed to accommodate a variety of bullet styles while maintaining good accuracy in an AR.
We also know from both public and private statements that several, more conventional, throat designs were tried during the early development. Some of these provided excellent accuracy with some bullets, but not so good accuracy with others. Some of these earlier designs look a lot like the "alternative" chambers floated by others, including the chamber suggested as being the one Satern is now advocating and selling.
Bottom line, e caveat emptor.
Compare your scraped Satern throat with the one in your PF Neptune V. They should look alike. If not, at least one of them is not a Grendel chamber. What you conclude is worth bothering with is up to you, but folks need to know who produces barrels that meet the standards and who does not.
Now what I said JA, is yes there will be a "ring". It will not be as long as a .264LBC "ring"(freebore) but there will be one there.
... and my comment about now highlighted in bold green type tells us we are in agreement that comparing chambers and throats is a good thing to do.
Should he discover a difference, then safety and performance considerations suggest follow-up action is needed.
If they appear the same, then I will stand corrected and we will need to work out how to discuss these differences of interpretation and description.