Lyman's Data Discrepancy...what does your book say?

U

UncleLoodis

New member
Hello!

I have reloaded pistol for a long time, and am now starting to reload rifle cartridges. My friend and I were discussing data from Lyman's 49th edition, specifically dimensions of the .308 Winchester cartridge. We found that even though we both have the same edition, the given data differs between our two books.

Given dimension from bottom of case to top of shoulder (where neck starts) is 1.675". My buddy's book shows 1.712". Both 'test component' cases were Remington.

So I called another buddy, who also has the 49th version. His dimension info matches mine, 1.675".

I also have a Hornady reloading manual; it's dimension is 1.711", using Hornady cases.

So which dimension is correct: 1.675", 1.711", 1.712" ??

I took an unfired Starline case and measured with my calipers (eyeballed it) and it appears that the 1.711" or 1.712" dimension is correct, as the 1.675" dimension lands around the middle of the shoulder.

What say you? Do you have a 49th Edition...if so, what does it say for this dimension? How important is this dimension and/or discrepancy?

Thanks in advance,

Uncle Loodis
 
When in doubt, just look at the SAAMI drawings. Looking up facts always beats opinions about them.

Go here. At the top is a blue link to cartridge and chamber drawings. Click on that, and from the drop-down list, select Rifle. You'll then get a download of the drawings in PDF format. In Acrobat reader, hold down the Ctrl key and press F. The Find window will come up. Write "308 Winchester" in it (without the quotation marks) and then keep clicking on the Next button below and on the right side of it until the drawing shows up.

What you will find when you get there is the SAAMI dimension is 1.7116". It's a reference dimension, meaning it's not a specification but an FYI number. It is to the neck and shoulder intercept, but the real cases have a radiused corner, so you won't find it with your caliper exactly. If you look right above it you will see the headspace dimension is 1.634" with a tolerance of -0.007". The 1.7116" number will correspond to the maximum and will also be pushed back -0.007 when tolerances are included, so a range of 1.7046-1.7116" is what you would get, and most new brass is on the shorter end of that range.
 
SAAMI Spec is 1.7116" (and my SAAMI Ref p112 doesn't have a range)

My Lyman 3rd Ed Cast says 1.711
My Lyman 4th Ed Cast says 1.675

Lyman 48th says 1.711
Lyman 49th says 1.675

Duuuuuuhhh...??
 
Thanks!

Thank you Unclenick for that great information! Since typing my post, I found that I have the 4th printing of the 49th Edition, and my friend with the accurate info has the 10th printing. So somewhere along the line, Lyman's corrected their book.

Again, that is a great reference link. I appreciate the info! Thank you! :)

U.L.
 
I can confirm both Mehavey's sets of numbers in my copies, too. Editorial error. I looked through all the current SAAMI drawings to see where it might have come from. My first thought had been the 308 Marlin Express, but it's too short. The closest is the 338 Federal, for which the range is 1.6750"-1.6757", but it's the larger number that's given, as it's the critical fit dimension. So, I don't know. Whoever put it there was looking at a wildcat drawing or something.

Glad to know they fixed it. Probably had a lot of folks like us writing them.
 
From now on, I think I'll just go to the SAMMI specs instead of anyone's book. What's interesting is that I Googled quite a few combinations of words including "Lyman's", "discrepancy", "typo"...etc., and never found anything. Then I thought, "What am I doing? I should just go to TFL and I'll get some good info!" And I did.
 
MeMyself&I said:
SAAMI Spec is 1.7116" (and my SAAMI Ref p112 doesn't have a range)

My Lyman 3rd Ed Cast says 1.711
My Lyman 4th Ed Cast says 1.675

Lyman 48th says 1.711
Lyman 49th says 1.675
Click to expand...
That that I will add...

Lyman 50th says 1.712 (which is true SAAMI Spec)
 
It's the reference number rounded up at the LSB. The SAAMI drawing says 1.7116", but most folks won't be able to measure that last decimal place. If you look at the CIP drawing, which does use that number as a defining specification (CIP doesn't use a shoulder datum), they give the maximum as 43.48 mm (1.7118"), with the difference due to the last hundredth of a millimeter of the metric conversion not hitting the last digit exactly.
 
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