JASmith Wrote: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.

Walter Wrote:Bjorn. Mark was sure that the throat was short. Mark has alot to do and I do think he would put the time in to document the problem. He did ask me " if I thought Steve Saturn did not know the chamber is short". There is no reason to do the casting, they are short. I think everyone knows that.

Soyben. Marks reamer is made off the AA print. I think the liberty barrel reamer is made wrong. I would go with Mark and be sure your barrel is fixed correctly. After talking with him I am sure mine will be fixed correctly.

JASmith Wrote:Why don't you re-check the SAAMI drawing? I just did and could not find the feature you describe. The 0.5 degree reduction in diameter from .2644" to .2677" starts at 1.5478" and ends at1.7025" for a run of 0.1277 inches. That should not produce a 'ring-like' appearance. k.

woohoo Wrote:I don't need to recheck it, I've known what it looks like for 5-6 years.

Quote:IF any part of the throat is .264 or larger there will be NO lands. The groove in the barrel is .264. If the reamer removes material .264 or larger it will remove all of the lands making a smooth bore...freebore.

Quote:Your numbers are wrong, the area where the lands slope a .5 degrees starts at .2644 and they get taller to .2617. Notice the .2644", that is larger than .264 and will remove all of the lands.

JASmith Wrote:With all the respect owed to a well-known and respected gunsmith, this comment suggests that one may have lost the desire to learn new things.

Based on looking at and reading the drawings, I concur with your observation:





I was truly hard-pressed as to why you could say my numbers are wrong when yours agree with my memory and those on the drawing -- until I re-read my post and realized I had misstyped! BTW, tapering out from .2644 to .2677 and then starting a 1.5 degree slope down to bore diameter would create an interesting picture! Many thanks for calling my attention to the error. I have just corrected the typographical error.

I am still hard pressed to find a feature in the drawing that would evoke the appearance of a ring "just before where the lands start" as described in post #17.

I will concede that the observer may have confused the neck-freebore transition with where the lands start, which would explain the differences and why we don't seem to be on the same page in this discussion.

woohoo Wrote:I look down about 70 barrels a day on average. I'm sorry you are confused about what would look like a ring. Let this guy shoot his barrel and see how it shoots before you worry the s*** out of him by not knowing what would look like a ring and what would not. If you don't understand that a reamer larger than the bore would remove ALL of the lands you'll need to find someone that has more time than me to explain it to you.

JASmith Wrote:Are you deliberately misrepresenting my comments?

This guy should be worried given that the operation was described as a "scraping" rather than retouching with a finishing reamer.

Add to that his observation of an unexpected feature that cannot be be explained by the SAAMI drawings, and he should be worried.

Yes, someone who looks down 70+ barrels a day and has developed a reputation for excellent workmanship should understand this.

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.