Why do SAAMI cartridge drawings contain TWO drawings?

[JimGnitecki]

Why do SAAMI cartridge drawings contain TWO drawings? Here is an example (the 6.5 Creedmoor SAAMI cartridge drawing set):



The one difference obvious to me is that the bullet is not shown in the second drawing. But there are other differences that I do not understand.

For example:
In the top drawing, the base to top of neck dimension is 1.920" -.020"
In the bottom drawing that "apparently" same measurement is shown as 1.925", which would appear to contradict the 1.920" -.020" in the top drawing.

Can someone who understands the SAAMI drawing specs provide some clarifications?

Jim G

 

[Sefuller5741]

I think the second drawing might be the chamber?

 

[Blue68f100]

The second is the chamber spec.

 

[JimGnitecki]

Ah, thank-you both! That makes sense.

Jim G

 

[DocRock]

^^^^^^

One for cartridge; one for chamber.

 

[Mark_Mark]

one for earth and one for mars! yes, different atmosphere pressures

 

[JimGnitecki]

Yes, what stopped me from even thinking about the 2nd drawing being for the CHAMBER is that SAAMI calls the whole drawing set a "CARTRIDGE" specification!

Jim G

 

[edwardware]

Why do SAAMI cartridge drawings contain TWO drawings?

They don't. The second drawing is a chamber, not a cartridge.

 

[higgite]

Yes, what stopped me from even thinking about the 2nd drawing being for the CHAMBER is that SAAMI calls the whole drawing set a "CARTRIDGE" specification!

Jim G

Note on the lower right side of drawing where it says "CHAMBER". That's a clue.

 

[alfsauve]

For cartridge dimensions they give the max size with a negative tolerance. And for the chamber the minimum size with the positive tolerance.

 

[shoobe01]

Note on the lower right side of drawing where it says "CHAMBER". That's a clue.

And even right above where it says the 6.5 Creedmore "Maximum Cartridge / Minimum Chamber" as a title for the whole thing. Slash: both.

It's all in there, you just need to know how to read dense engineering drawings.

 

[NMexJim]

It's labeled right on the drawing - Cartridge upper drawing and Chamber lower drawing.

 

[JimGnitecki]

For cartridge dimensions they give the max size with a negative tolerance. And for the chamber the minimum size with the positive tolerance.

That makes sense! That ensures that a cartridge made to maximum spec will always fit inside a minimum spec chamber. Makes the specs and tolerances understandable.

Jim G