6.5cm sammi specs vs my actuals

[chadrp]

I'm another reloading newbie and am just curious as to why my numbers are smaller than the sammi specs. I'm measuring with a forster datum tool on the 400 setting and decapped.

New Hornady brass measures 1.53

My once fired factory Hornady measures 1.5360-1.5365

Sammi cartridge specs 1.5438-.007

Sammi chamber specs 1.541-1.551

Thanks!

 

[Supersubes]

Saami specs mean almost NOTHiNG to the handloader. All that matters is your chamber and sizing die. If those two things work together, you’re done.

 

[chadrp]

Yeah, I understand that for reloading measure my stuff and taylor the reload to it.

This is a barrel from the PVA Nucleus preorder that I thought were all cut to sammi specs yet it seems to be slightly smaller?? I'm not complaining just trying to learn and understand headspace numbers and all, I thought it would be a little closer to specs.

 

[chadrp]

Also sorry bout all the extra attachments it kept saying oops ran into problems and now it wont let me delete them lol

 

[Supersubes]

The proof is in the pudding here. Your measuring tool is for comparative measurements, not “gauging”, and the only comparisons you need to be making is between virgin, fired, and sized brass. This topic comes up regularly by the way.


Edit: having a set of go/no-go gauges in this case is nice. They’d provide another comparative measurement using your tools.

 

[chadrp]

The proof is in the pudding here. Your measuring tool is for comparative measurements, not “gauging”, and the only comparisons you need to be making is between virgin, fired, and sized brass. This topic comes up regularly by the way.


Edit: having a set of go/no-go gauges in this case is nice. They’d provide another comparative measurement using your tools.

Yeah, I'm working on reading the forster sizing die question and seeing the same thing... guess something's just arent supposed to make sense lol

Thanks!

 

[A&8's]

Cerrosafe your chamber.

 

[Steel head]

Looks good.
Shoot it.

 

[spife7980]

The short of it is the hornady comparators are exactly that, they compare, they are not an absolute gauge

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[chadrp]

The short of it is the hornady comparators are exactly that, they compare, they are not an absolute gauge

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Thank you for the informative post, I hadn't considered needing to measure an accurate known headspace gauge to know how close your comparator is but that makes sense. Thanks again for the help.

 

[spife7980]

Thank you for the informative post, I hadn't considered needing to measure an accurate known headspace gauge to know how close your comparator is but that makes sense. Thanks again for the help.

Yep, to know exactly you need a known standard.

But to reload accurate ammo you really only need to know fired vs sized in your chamber. Which the hornady/Sinclair comparators do a great job of.

 

[chadrp]

Got it, and now have a better understanding of it. I will get all my measurements written down and put them in my data book.