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woohoo Wrote:Arne was shooting a 6.5 in PPC brass long before Bill but it was more like the 264LBC. It had a .291 neck diameter and typical throat. I had 2 of them. Arne was the first to shoot a 6.5 in a PPC case but it was not a "Grendel"
This is Arne's 6.5 reamer drawing from 1998.
http://i5.photobucket.com/albums/y158/cu...rennan.jpg
ya know, looking at that, it matches closer to what I'm measuring on my Lilja Barrel. Look at my post 271 from http://www.65grendel.com/forum/showthrea...rns/page28 . is that possible to match this reamer measurements? or Close??
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Tedward Wrote:I have an AA barrel in the mail, I will take the measurements as soon as it arrives and be able to compare all of them I have. Even with my findings, it still won't help prove, confirm or make anything right or wrong. Just posting the numbers from each manufacture would be nice for everyone to know what they will get if they buy a barrel from manufacture "X", "Y" or "Z".
Then if they plan to hand load heavy bullets, buy barrel "Y". Load light pills, use barrel "Z" and if you want to use factory ammo, buy barrel "X". It seems there is a big variation in bullet seating depths so once it is identified who makes what, we will see where the line forms and who is going to be back ordered and wait for there desired barrel manufactures product. And $$ will play into that also.
As a "normal" consumer I totally disagree with this. If I order a damn Grendel barrel from a commercial supplier I want a real unmolested Sammi spec grendel that will chamber what it is supposed too, see:factory ammo! If I need some half breed abortion barrel I will pick up the phone, call a barrel maker and have it made to my specific desires and wear the safety liability on my own shoulders.
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jluck Wrote:As a "normal" consumer I totally disagree with this. If I order a damn Grendel barrel from a commercial supplier I want a real unmolested Sammi spec grendel that will chamber what it is supposed too, see:factory ammo! If I need some half breed abortion barrel I will pick up the phone, call a barrel maker and have it made to my specific desires and wear the safety liability on my own shoulders. Yes I agree that if you buy a Grendel, you get a Grendel, it needs to chamber factory ammo safely and correctly. What I'm saying is there are acceptable tolerances that can go to the high side and let people hand load heavier bullets. You might be able to load 140gr projectiles with one manufactures and not the others and still be in the Grendel Spec.
Tedward Wrote:Who cares, stop rolling in the mud. Just thought that was funny, mud, pig  .....but really, we can't keep digging in the crap pile or we can't move forward.
I care. It is a potential safety issue... Higher velocities DO NOT come without higher pressures.
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PigOPs Wrote:I care. It is a potential safety issue... Higher velocities DO NOT come without higher pressures. Do you think talking to XCR will help? Nope, drama
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JASmith Wrote:Bingo!
The lines of the throat are consistent with SAAMI. SAAMI tolerances are -0.00" to +0.002" while PTG uses + - 0.001" for the tolerance. In theory, this would mean that half of the reamers produced would be smaller than the SAAMI spec.
In reality, the propensity to cut tight chambers means that a larger fraction of the throats end up being too tight.
Has anyone pointed this out to PTG?
I don't see where you are getting +-.001 from that drawing, unless you're going off the fraction tolerances. Which when you look closely there isn't a single fractional call out. Since they are all decimals wouldn't they be going off the decimal tolerance at the bottom of the sheet which is -0.000 +0.0004. There is the weird jargon at the very top of the page but as far as a print goes, the bottom section would over ride that.
Print link : http://www.65grendel.com/forum/attachmen...entid=4664
If the chambers were cut to the decimal .0004 tolerances there wouldn't be any problem seating 30 thou past factory ammo spec and the ammo wouldn't have to be mortared out or debulleting problems,etc. that some barrel owners are having.
My barrel seems to be good enough but i don't think people are making stuff up.
I've seen a bughole group shot in a 24 inch AA barrel with 123 A-maxs loaded to 2.29.
I'm sure PTG makes good reamers but something went wrong somewhere.
A factory round shouldn't stick in the barrel.
Adam Lilja Wrote:I don't see where you are getting +-.001 from that drawing, unless you're going off the fraction tolerances. Which when you look closely there isn't a single fractional call out. Since they are all decimals wouldn't they be going off the decimal tolerance at the bottom of the sheet which is -0.000 +0.0004. There is the weird jargon at the very top of the page but as far as a print goes, the bottom section would over ride that.
Adam,
Thanks, you are demonstrating the value of polite discourse to get some of these details thrashed out!
After first admitting that I did not earlier do detailed research on the term "fractional tolerance" I did a more thorough review so I could better respond to your comment.
As near as I can tell from the discussions of "fractional tolerance," there is no standard defining them. Most of the discussion refer to fractions of an inch, e. g. "1/4" "i/8", "1/64", etc.
At this point one takes the dangerous step of assuming that the call-out using a decimal means that the drawing actually means +1/1000" to - 1/1000" with the key question being: "What does the use of a decimal in a fractional call-out imply?"
So, one assumes that, absent a discussion of how tolerances are applied by the reamer maker, we take the most liberal interpretation.
Should you or any other fellow (or sister) forum member have insight that would help clarify, please pipe up with a definitive answer.
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JASmith Wrote:Adam,
Thanks, you are demonstrating the value of polite discourse to get some of these details thrashed out!
After first admitting that I did not earlier do detailed research on the term "fractional tolerance" I did a more thorough review so I could better respond to your comment.
As near as I can tell from the discussions of "fractional tolerance," there is no standard defining them. Most of the discussion refer to fractions of an inch, e. g. "1/4" "i/8", "1/64", etc.
At this point one takes the dangerous step of assuming that the call-out using a decimal means that the drawing actually means +1/1000" to - 1/1000" with the key question being: "What does the use of a decimal in a fractional call-out imply?"
So, one assumes that, absent a discussion of how tolerances are applied by the reamer maker, we take the most liberal interpretation.
Should you or any other fellow (or sister) forum member have insight that would help clarify, please pipe up with a definitive answer.
Well, as a machinist, if I got that drawing on the floor I would use the decimal tolerance call-outs (+0.0004) , unless there was a spot where they were called out in actual fraction form (1/8, 1/4, 1/2) for which I would apply the +-0.001. Don't know if that helps or not.
Also, I'm not saying that the reamers are or are not right or wrong, I'm just saying that the print is right.
Thanks. You have helped highlight the differences between how some engineers and some machinists interpret drawings.
It helps when conversations, preferably face to face, occur to work things out. Even then, we can be reasonably certain that mistakes can happen.
The important thing is informed QC on the finished product and how confusion and errors get resolved.
We all learn a bit each day!
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![[Image: 2eurkok.png]](http://i58.tinypic.com/2eurkok.png)
#FTW
TheEnigma Wrote:
#FTW Question for you. The shape you show above looks like what a button would look like used to rifle a BHW barrel. I looked at one with a borescope. The lands look like they are very very thin like the points of the white part of the shape above.
Is the black part of the shape above the shape of the buttons used to rifle a BHW barrel?
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BHW uses what they call polygonal rifling, hence the abnormal shape.
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BHW uses the .264 LBC, not the 6.5 Grendel. Granted, it was meant as a Grendel clone and does fine with factory rounds, but I want to say there's a throat angle difference. Can't seem to find the Grendel's (LBC is 1 degree I believe), but I did find something interesting. Satern says throat is not part of SAAMI, Bill A. begs to differ: http://www.65grendel.com/forum/archive/i...-3445.html
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Like I said, I knew it was meant as a clone, so they're pretty much the same. But in a discussion based around people calling something that is not a Grendel a Grendel, it seemed a little strange. Still interested how Satern thinks throat is not SAAMI when the maker says it is.
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As far as I know, the .264 LBC was meant to shoot 123 Amax, and shoot it well. And it does just that. SAAMI or not, sub MOA groups don't lie. My buddy has a 24" LBC that holds 3/4 MOA out to 300 or so. I was hooked after the first shot!
TheEnigma Wrote:BHW uses what they call polygonal rifling, hence the abnormal shape. Yes I know but that poly does not look like HK or Glocks poly, it looks opposite. That's what I thought when I saw the skinny lands with the bore scope.
ThatRandomGuy Wrote:BHW uses the .264 LBC, not the 6.5 Grendel. Granted, it was meant as a Grendel clone and does fine with factory rounds, but I want to say there's a throat angle difference. Can't seem to find the Grendel's (LBC is 1 degree I believe), but I did find something interesting. Satern says throat is not part of SAAMI, Bill A. begs to differ: http://www.65grendel.com/forum/archive/i...-3445.html
Check the SAAMI link in this sticky: http://www.65grendel.com/forum/showthrea...l-Drawings
The sticky is at the top of the "6.5 Grendel Ammunition & Reloading" section so it should be easy to find. Clicking on the link above might be easier.
The throat is indeed defined in the SAAMI specification.
You will also find the throat angles on the drawing.
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