Case Tolerance on Sizing Question


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mtod01
December 28, 2008, 10:32 PM
I'm new to reloading.

I was looking at the brass I have been saving to start reloading and picked up a Lee and Hornady Reloading Manuals.

I measured a 45 ACP once fired case.

I found that the once fired case was way off the specs in the books.

So the question that came up was how far off can it be before I toss it.
I could not find any books or web sites that would give me the allowed tolerances for a give case.

Any idea where this information can be found?

Example:
Winchester 45 ACP Target 230.

Length s/b .898 Winchester is .887
Dia. s/b .473 Win is .471
Inside Dia. s/b .451 is .448

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243winxb
December 28, 2008, 11:03 PM
After your case is sized, it should be somewhere close. The measurement you list are within normal range. Click on the 45acp link http://www.stevespages.com/page8d.htm

mtod01
December 28, 2008, 11:15 PM
I like to be some what exact that site does not show any tolerances.

243winxb
December 28, 2008, 11:40 PM
There are to many variables to be exact in reloading. The drawing(link) is to SAAMI specifactions. The reloading dies work within a given +/- tolerance. Bullets are the correct size, .451" jacketed or .452" lead/cast.The expander plug(.449") forms the inside of the case for the bullet. You need to trim brass for length after full length resizing. (45acp rarely needs trimming) The size of the guns chamber tells you if you ammo is with in specification. Too big and ammo will not go in the gun. hope this helps

Dean Williams
December 28, 2008, 11:40 PM
I like to be some what exact that site does not show any tolerances.

You are not going to be able to be "exact" with some cartridge dimensions. There are minimum and maximum dimensions that are within industry standards, but there is not an exact size for something like case length.
For instance, using your 45 ACP cases, the max length is .898", and the trim-to length is .888". Between those dimensions the cartridge should chamber in any factory barrel for that caliber without being too short or too long.

You need to measure the length of your brass after you resize it, and your brass will be out of "spec", as you say, until that step is done. Sizing will put it back to certain accepted dimensions, and in the case of 45 ACP, taper crimping may do a little more.

mtod01
December 28, 2008, 11:43 PM
I think the term exact was the wrong term.

What I should have said is I would like it to be with in tolerances.

But with out knowing what the tolerances are I can't be sure.

243winxb
December 28, 2008, 11:47 PM
hope this link works http://www.stevespages.com/page8d.htm click on the 45 acp, these are the correct tolerances. The loaded ammo should not be larger than this.

mtod01
December 28, 2008, 11:49 PM
Thanks I'm learning.

I think the term exact was the wrong term I should have said I want to be within standard tolerances. But with out knowing what they are I can't be sure.

I would have thought that SAAMI would have the tolerances listed for the standard casing (not die) but I can't find any.

I have worked in Machine shops in the past and we allways had a specification the included +/- tolerances for every design.

mtod01
December 28, 2008, 11:52 PM
Yes the link worked thanks.

It show only the expected demientions there are no +/-.

Like for 45 ACP
Length s/b .898 +/- .010

So I would know that .888 - 908 would work fine.

it only shows .898

243winxb
December 28, 2008, 11:57 PM
SAAMI sells the imformation like the drawings on steves pages. Some you can fine for free on the internet. Like pressures http://www.handloads.com/misc/saami.htm Some times you run into reamer drawings and other stuff. http://www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?p=0&t=1&i=1305&mc_ID=2019 <<< this is a must read, great info.

Dean Williams
December 29, 2008, 12:00 AM
If you want to know what the trim-to length is, which I think is what most of us consider a minimum to trim to once the case is over length, check out Speer or Lyman manuals. I believe they both have this length called out.
My latest Speer is #12, and I think my Lyman is #47. Not the latest, but they show it.

The specs the linked website (above) shows maximum dimensions.

mtod01
December 29, 2008, 12:09 AM
Thanks I guess some of this is terminology.

I looked in my Hornday book and it has that also.

So that brings up another question I have a lot of once fired Winchester and Blazer 45 ACP cases.

I measured several and they seem to come out as follows:

Win length .887
Blazer length .891

This is of course before resizing.

1. Will resizing lengthen the case?
2. if not then both of these cases are under the Case trim length of .893

fireman 9731
December 29, 2008, 12:10 AM
As long as it goes in and out of your die, Im sure it is within tolerances...

Jim Watson
December 29, 2008, 12:32 AM
.45 ACP case length and tolerance per SAAMI is 0.898" + 0, - .010", so the spec range is 0.888" - .898". I have seen not over half a dozen too long and they were all range pickups of the same headstamp, likely out of one off-spec box. I have seen a lot shorter than the official minimum and it makes no difference in my shooting. One advantage of a taper crimp is that it is less critical of case length than a roll.

Maybe if I were a NRA Master wanting the very best at 50 yards, I would be more choosy. But I'm not.

mtod01
December 29, 2008, 12:50 AM
Thanks for the quick replies.

This is good information.

Mike

mtod01
December 29, 2008, 12:52 AM
Jim did you have to buy the SAAMI specs to get that information on the +0 -010 Tolerance?

243winxb
December 29, 2008, 07:48 AM
The maximum case length is a given. The standard is set by SAMMI i think, just a guess:confused: The minimum trim (-.010") length from the maximum is more or less standard for all calibers. There may be a few exceptions when its -.005" . Reloading manuals and case length charts confirm this. I have never had to trim a 45acp case and i have shot 1000's.

243winxb
December 29, 2008, 07:57 AM
CCI Blazer Ammunition combines a non-reloadable aluminum case 1. Will resizing lengthen the case?
2. if not then both of these cases are under the Case trim length of .893 The case should get longer with full length resizing. DO NOT worry about short cases. 45acp rarely need trimming, but always check case length after full length resizing to be SAFE.

Walkalong
December 29, 2008, 08:54 AM
Worrying about nothing.

Like Jim said, you will find very few cases out of spec. I shoot a horrid mix of range brass with excellent results. I never measure the cases. If they feel OK going through the sizer, and the bullets feels OK seating, I shoot them. I do cull Amerc cases.

Jim Watson
December 29, 2008, 09:55 AM
Jim did you have to buy the SAAMI specs to get that information on the +0 -010 Tolerance?

No, I have the NRA Handloading manual, edition of 1981, with SAAMI-ANSI chamber and cartridge drawings in the back. Doubt the standard calibers have changed in 27 years.

Interesting note: They show separate drawings for .45 ACP and .45 Match. The chamber dimensions are the SAME. Remember that when some gunzine ad touts a "minimum match chamber". The spec IS the minimum, all chamber tolerances are plus, cartridge tolerances are minus, to ensure a maximum round will fit a minimum gun.
(Military National Match chamber specs are shorter than commercial.)
[The Match cartridge drawing shows a SWC OAL 1.255" instead of a RN OAL 1.275" maximum. Brass dimensions are the same.]

rcmodel
December 29, 2008, 12:11 PM
Seems the fired case must have been somewhat in spec to become a fired case in the first place!

You can't tell diddly-squat by trying to measure fired cases before they have been resized.
Don't even confuse the issue by trying.

A case fired in a gun with a very loose chamber will get a lot bigger around and shorter.
A case fired in a very tight chamber, not so much, but still some.

Once resized, they all get smaller and longer and back close to spec.

rcmodel

rfwobbly
December 29, 2008, 02:50 PM
You can't tell diddly-squat by trying to measure fired cases before they have been resized. Don't even confuse the issue by trying.

Agreed.

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