Why can’t we get good dies!

Skimbleshanks

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The answer to the question "why cant we get dies based on SAAMI min spec?" comes down to something called GDT. Geometric Dimensioning and Tolerancing. It is a system where all your + dimensions and all your - dimensions must be compatable. Believe it or not but depending on the datum measured from, a +/- .010" hole sometimes needs to be over, +/- .010". Working from min dimensions, and expecting everyone who cuts chambers, dies, or makes brass to be on the exact same page, and for tooling to never wear, Is kinda like asking for a unicorn.

That is a VERY rough explanation, and no I don't want to go grab that textbook or delve deeper into it. When I finished that class I was very happy.

TLDR: Go look up GDT.
 

Tiny Tim

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The answer to the question "why cant we get dies based on SAAMI min spec?" comes down to something called GDT. Geometric Dimensioning and Tolerancing. It is a system where all your + dimensions and all your - dimensions must be compatable. Believe it or not but depending on the datum measured from, a +/- .010" hole sometimes needs to be over, +/- .010". Working from min dimensions, and expecting everyone who cuts chambers, dies, or makes brass to be on the exact same page, and for tooling to never wear, Is kinda like asking for a unicorn.

That is a VERY rough explanation, and no I don't want to go grab that textbook or delve deeper into it. When I finished that class I was very happy.

TLDR: Go look up GDT.
Great explanation. Most rifle manufacturers assemble things to work, as do die manufacturers. We often fail to see a greater overall picture of business and how it works. Most of these manufacturers are just that, production oriented manufacturers rather than custom shops. While this may be a "common" problem for some, it doesn't affect the vast majority of shooters and reloaders, as evidenced by the responses in this post. If we make something to either the min or max of a spec, we can't assume every other manufacturer will do the same thing to the same end of the tolerance. Thanks for the explanation.
 

Alex Wheeler

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This is usually more of an issue for well built rifles. In a factory rifle or sloppy custom rifle, the chambers will typically be wallowed out. Reamers will cut oversized chambers when the setup is not perfect. In that case the oversized dies work with the oversized cases from the over sized chambers. But if your gunsmith is producing chambers that measure what the reamer measures, like he should be, then you will struggle at times to find a good die.
 

milo-2

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These mis-matches, clickers, can be tough at times to decipher also. Not everyone is measuring cases head to toe after firing, add in not having the reamer specs as a guide.
One of the first thoughts is over pressure, which can be far from the case, if the case has adhered to the chamber wall, when you lift the bolt, case isn't turning with the bolt, and scrapes brass, now your bolt face has a buildup on it. That is magnified if the bolt face is coated with cerakote, so every consecutive shot the case head is marred up some, so we assume hot load.
Or in some cases, we point fingers at primary extraction, and all actions are not created equal in that department.
 

Stiltsville

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OMG spit coffee all over my keyboard !

You really think cases turn with the bolt lifting ? Got some videos ?

Read up on the Walther G3.
 

del2les

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Through the decades, when we wanted custom dies with very close tolerances to better fit our custom chambers, we simply sent 2-3 fired cases to the die manufacturer with our stated desires. Over the decades, RCBS and others have made several of these for us. Most, if not all, of my old BR dies were customs.

Standard off-the-shelf factory dies usually have loser tolerances to cover a wider range of chamber dimensions, but even then, there are ways to make "most" of these dies perform better. YMMV
 

crazyhorse

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Empty barrels always make the most noise
Obviously opinions aren't in short supply for this guy. He's been a member for less than a month and already over 300 comments. There's another forum he should check out where all the "snipers" hide and seem to enjoy negativity and frequent arguments.
 

eshorebwhntr

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OMG spit coffee all over my keyboard !

You really think cases turn with the bolt lifting ? Got some videos ?

Read up on the Walther G3.
How would a once fired case like the one pictured get these marks without rotating in the chamber during extraction?

0615201404a.jpg
 

Rhovee

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Pretty easy experiment. Color a case body and shoulder with sharpie. Insert and run the bolt open and closed a bunch of times. You will see where it’s getting marked up by the chamber if you haven’t sized the case.

Or remover the bolt and hold a case against the bolt face with ejector and extractor working against each other to hold case straight. Try and spin the case while holding it straight.

Or how would stiff bolt lift be present if the extractor didn’t grab the case head at all?
 

nvschütze

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I had Ben Syring of Hornady Manufacturing design four forming dies and two reloading die sets for my two mildcats. I'll have him design the dies for my next project. Dave Manson will make the reamer and headspace gauges. Lee Precision will make the trimming mandrel.
 

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eshorebwhntr

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Chamber marks from the reamer.....
I guess I assumed if that was true and they were imprinted like that, as opposed to scraping from rotating during extraction, that the scoring on the case would be present all the way up the case wall.
 
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