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.280 AI controversy explained ...

 
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  #99  
Old 08-15-2013, 03:55 PM
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Re: .280 AI controversy explained ...

Quote:
Originally Posted by woods View Post
Here's a one-liner, if there are 2 different go gauges, then how can they have the same headspace?
The datum line is at a different point on the guage thus the length is different because your measuring at two different points on the angle.

How does the guy in the video end up with the same head space using the two different guages??
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  #100  
Old 08-15-2013, 07:09 PM
Edd Edd is offline
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Re: .280 AI controversy explained ...

Quote:
Originally Posted by yawn View Post
That's great , So you have an answer to my questions in post 74 then? Because so far every time I ask them everyone clams up.
Ill even put the link up again.
https://gunsmithtalk.wordpress.com/2...eadspace-test/
Post the specs of whatever you have a question about and your question and I'll answer it.
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  #101  
Old 08-15-2013, 09:14 PM
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Re: .280 AI controversy explained ...

Quote:
Originally Posted by Edd View Post
Post the specs of whatever you have a question about and your question and I'll answer it.

Iv seen enough spec sheets thanks and the change of datum theory that argues against it. I'm far more interested in actual physical tests and anyone with an understanding of go/nogo gauges will realize that what they showed is actually impossible if there is a .014 difference between the two. So my question is how do they get that result? If they are wrong then how so?
Also worth considering they actually set out to prove their original post but ended up having to do a complete U turn with what they found.
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  #102  
Old 08-16-2013, 10:20 AM
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Re: .280 AI controversy explained ...

Quote:
Originally Posted by woods View Post
Here's a one-liner, if there are 2 different go gauges, then how can they have the same headspace?
<G>!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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  #103  
Old 08-16-2013, 08:06 PM
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Re: .280 AI controversy explained ...

Quote:
Quote:
Originally Posted by woods
Here's a one-liner, if there are 2 different go gauges, then how can they have the same headspace?
Quote:
Originally Posted by Trickymissfit View Post
<G>!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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  #104  
Old 08-16-2013, 10:16 PM
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Re: .280 AI controversy explained ...

I think he means why would they make two sets of gauges if they both give the same measurement? Which is a fair question.
Possible answers might be ; they are actually different? OR for the opposing team: the new sammi spec had different measurements from a different datum and was never actually checked against the older version just assumed to be different?
As I see it the only way to be 100% sure is to try the two different sets in one chamber which seems to have been done by gunsmith talk. But I could easily be missing something here so I'm remaining open minded.
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  #105  
Old 06-03-2014, 08:41 PM
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Re: .280 AI controversy explained ...

I just read all of that...and I don't see what is so confusing.

Quote:
Well, when you check the drawings from SAAMI and the Traditional drawings for the Ackley Improved you find that indeed there is a numerical difference between the two drawings of .014″. The problem stems from reamer makers applying a datum line to the Traditional Ackley drawing at the .375″ diameter on the shoulder, this is not where the datum line is on a traditional Ackley.

The drawing calls for a 40 degree shoulder, but the datum measurement is based on the traditional 17 degree gauge. In other words the systems of measuring are mixed. Ackley used the junction of the neck and shoulder to headspace his Improved chamber, not the datum line along the shoulder.

Hence we end up with a headspace length of 2.1542″ on the Traditional drawing. I measured this length on my cutaway chamber and guess what, that is the length to the junction of the neck and shoulder. Thus headspace matches the drawings correctly.

The 40 degree SAAMI gauges are made to the industry standard, datum line method. So the drawings are correct, the datum line is at the .375″ diameter along the shoulder. The length called out for this gauge is 2.140″, which appears to be .014″ shorter than the Traditional design.

What we have is two different methods of measurement. However they achieve the exact same result.
There are two reamers, gauges, etc because some makers are measuring to a different spot...the neck/shoulder junction or the .375 datum line...Ackely used the neck/shoulder junction...SAAMI uses the .375 datum line...the datum line (down on the shoulder) is .014" closer to the head of the case than the neck/shoulder junction.


That could be all wrong...but thats what I get out of reading all this stuff...I don't have a 280AI just yet (very soon, with a Nosler chamber)
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