chamber and die dimentions

[mrjdasr]

try to keep this generic and not step on toes
i have a drawing i down loaded from ammo guide for a.260 Rem
i assume the dim on that drwg are saami for the case and that the chamber dim will be slightly larger
particular the shoulder dim of .454 on the brass. my fired brass measures .456
am i correct with this thinking???? more to follow when this is resolved

 

[retired]

go down load the chamber drawing for SAAMI.
specs are specs, what was used on your chamber can be any where in the spec.
a nice what to chamber is to buy dies from a company that buys their die reamers from a known reamer maker, then buy a chamber reamer that follows the die reamer.

try to keep this generic and not step on toes
i have a drawing i down loaded from ammo guide for a.260 Rem
i assume the dim on that drwg are saami for the case and that the chamber dim will be slightly larger
particular the shoulder dim of .454 on the brass. my fired brass measures .456
am i correct with this thinking???? more to follow when this is resolved

 

[dcali]

There are two saami specs - one for the case and one for the chamber. You can access them for free on the saami website. That will tell you what you want to know.

 

[Bart B.]

a nice what to chamber is to buy dies from a company that buys their die reamers from a known reamer maker, then buy a chamber reamer that follows the die reamer.

Are you saying the die chamber and barrel chamber dimensions be the same?

If so, then the die's headspace with a standard shell holder will be that of a GO headspace gauge for the barrel chamber. Sizing die chamber headspace is typically. 004" to .005" less. And die chamber body diameters have to be smaller than barrel chambers else fired case body diameters won't get sized down. If you want to full length size fired cases to make them as straight as possible.

 

[riflewoman]

Are you saying the die chamber and barrel chamber dimensions be the same?

If so, then the die's headspace with a standard shell holder will be that of a GO headspace gauge for the barrel chamber. Sizing die chamber headspace is typically. 004" to .005" less. And die chamber body diameters have to be smaller than barrel chambers else fired case body diameters won't get sized down. If you want to full length size fired cases to make them as straight as possible.

No. The die specs should be a little bit smaller than the minimum chamber. But they probably won’t be smaller than the max cartridge.

Also don’t forget that there is an elastic spring back. Maybe as much as .002.

 

[KMart]

Is your chamber a custom chamber or a factory chamber?

If it is a factory chamber, what brand is the rifle?

 

[Bart B.]

The die specs should be a little bit smaller than the minimum chamber. But they probably won’t be smaller than the max cartridge.

All my FL sizing die chamber's are smaller than maximum cartridge SAAMI specs. Otherwise, they couldn't size fired cases down to specs or smaller. The 3 die companies I discussed this with say their FL dies size cases down to near SAAMI minimum to ensure they will chamber easily in minimum spec chambers. Therefore, those die chamber's are smaller than most new cases.

Have you ever dropped a new, minimum spec no-neck case into a stripped full length sizing die? If it doesn't go in all the way, it's fatter than the die chamber.

 

[243winxb]

i have a drawing i down loaded from ammo guide for a.260 Rem
i assume the dim on that drwg are saami for the case and that the chamber dim will be slightly larger
particular the shoulder dim of .454 on the brass. my fired brass measures .456
am i correct with this thinking????

Yes correct, but there are tolerances. .XXX" +/-

http://www.saami.org/specifications_and_information/index.cfm

 

[retired]

no . i am saying the die will size to fit the chamber.
minimal sizing required and the brass will last a long time.

Are you saying the die chamber and barrel chamber dimensions be the same?

If so, then the die's headspace with a standard shell holder will be that of a GO headspace gauge for the barrel chamber. Sizing die chamber headspace is typically. 004" to .005" less. And die chamber body diameters have to be smaller than barrel chambers else fired case body diameters won't get sized down. If you want to full length size fired cases to make them as straight as possible.

 

[mrjdasr]

try to keep this generic and not step on toes
i have a drawing i down loaded from ammo guide for a.260 Rem
i assume the dim on that drwg are saami for the case and that the chamber dim will be slightly larger
particular the shoulder dim of .454 on the brass. my fired brass measures .456
am i correct with this thinking???? more to follow when this is resolved

down loaded saami rifle files my ptg reamer is spot on
now to see if i can get a straight answer from manufacturers on a sizing die that will size to .454 shoulder dia
sending a die back to one maker after a minor disagreement
thanks for the replys

 

[Bart B.]

Why a .454" case shoulder diameter?

A little clearance from case to chamber there ensures the case shoulder will center perfectly in the chamber shoulder when fired. Especially if the case is a bit out of round. Few cases are perfectly round.

 

[ireload2]

Pay close attention to the individual SAAMI drawings.

1. The cartridge drawing is always for a maximum cartridge
If you look at the cartridge drawing you will find tolerances that always are plus nothing and minus something. That means the cartridge is not allowed to be larger but it is permitted to be smaller than the drawing dimensions. That is called MMC or Maximum Material Condition for the cartridge.

2. The chamber is always shown with minus nothing and plus something tolerances. So the chamber can get bigger but not smaller than the drawing by the amount of the tolerances.. Again the SAAMI drawing depicts the MMC of the chamber.

The biggest cartridge is by design supposed to fit the smallest chamber- always.....


The size of the loading die is dependent on the internal intellectual property of the die maker. It is whatever they think is best to produce cases sized to fit a SAAMI chamber.

Shooters for the most part are not really interested in the size of the die but in the size of the cases that come out of it.

 

[mrjdasr]

Pay close attention to the individual SAAMI drawings.

1. The cartridge drawing is always for a maximum cartridge
If you look at the cartridge drawing you will find tolerances that always are plus nothing and minus something. That means the cartridge is not allowed to be larger but it is permitted to be smaller than the drawing dimensions. That is called MMC or Maximum Material Condition for the cartridge.

2. The chamber is always shown with minus nothing and plus something tolerances. So the chamber can get bigger but not smaller than the drawing by the amount of the tolerances.. Again the SAAMI drawing depicts the MMC of the chamber.

The biggest cartridge is by design supposed to fit the smallest chamber- always.....


The size of the loading die is dependent on the internal intellectual property of the die maker. It is whatever they think is best to produce cases sized to fit a SAAMI chamber.

Shooters for the most part are not really interested in the size of the die but in the size of the cases that come out of it.

i am dealing with a brand new chamber in a brand new Bartlein barrel[ reamer by PTG] a fired case from this barrel has a .456 shoulder diameter. i am simply trying to find a resizing die that will give me a shoulder diameter of.454[the nominal diameter for a .260 Rem]
so far i got one from a manufacterer that gave me a .450 diameter. thats a lot of excess working on expensive brass
that die is going back where it came from dont want to go the custom die route if i can avoid it

 

[gunsandgunsmithing]

i am dealing with a brand new chamber in a brand new Bartlein barrel[ reamer by PTG] a fired case from this barrel has a .456 shoulder diameter. i am simply trying to find a resizing die that will give me a shoulder diameter of.454[the nominal diameter for a .260 Rem]
so far i got one from a manufacterer that gave me a .450 diameter. thats a lot of excess working on expensive brass
that die is going back where it came from dont want to go the custom die route if i can avoid it

I was going to say, most custom resize reamers are about .003" smaller than the chambering reamer. With springback, this typically yields a case that is about .0015 smaller at the shoulder and about .0005-.0006" smaller at the base.

I'd call PTG and talk to Dave himself. They make most of the reamers for most of the die makers. He may be able to tell you whose die to use with your reamer, for best fit.

Hope this helps,--Mike

 

[243winxb]

a resizing die that will give me a shoulder diameter of.454[the nominal diameter for a .260 Rem]

See the -.008" on the SAAMI cartridge drawing? I think this gives a tolerances of .454" maximum and .446" minimum??

 

[243winxb]

When using a FL bushing die , i want some clearence in the case body at the shoulder.
The clearence at the shoulder lets the case neck align correctly.

I only size 1/2 of the neck. The unsized part centers the round in the factory chamber.

At least, this is my thinking. If the bushing sizes all of the neck that it can, accuracy is not as good.

 

[mrjdasr]

When using a FL bushing die , i want some clearence in the case body at the shoulder.
The clearence at the shoulder lets the case neck align correctly.

I only size 1/2 of the neck. The unsized part centers the round in the factory chamber.

At least, this is my thinking. If the bushing sizes all of the neck that it can, accuracy is not as good.

 

[ireload2]

You need to realize that all normal manufacturing operations are aimed at the safe side of the tolerances. That is the direction that produces the highest probability of the brass fitting the chamber. The die company will get more field returns from larger die interiors than from smaller die interiors.
Some brands of dies are larger than others. From my experience 1960s Lyman dies are terribly tight on the body diameters.
Right now you are just hunting for a random over size die. I have done that and it is not a very good way to get what you want.
You can lap a die out or get a custom die made.
There is a chance that a trim die might have the dimensions you want. I have 2 trim dies that size the case some but they are larger than a FL sizing die.
You might check with RCBS, Hornady anf CH/4D engineering personnel.
.

i am dealing with a brand new chamber in a brand new Bartlein barrel[ reamer by PTG] a fired case from this barrel has a .456 shoulder diameter. i am simply trying to find a resizing die that will give me a shoulder diameter of.454[the nominal diameter for a .260 Rem]
so far i got one from a manufacterer that gave me a .450 diameter. thats a lot of excess working on expensive brass
that die is going back where it came from dont want to go the custom die route if i can avoid it

 

[Bart B.]

There are some misconceptions in this thread. I think they're based on how some think bullets are positioned in the chamber when rimless bottleneck cartridges are fired.

Once you realize that 243 Win, 260 Rem and 7-08 Rem straight cartridges will center their necks and bullets perfectly in a 308 Win chamber when fired, you may also learn that all commercial cartridge spinners do not align rounds to the dial indicator in the same way.

And a cartridge with a given neck-bullet axis angle to the case shoulder-body axis will show different runout values across all commercial spinners and their setup.

And any sizing die that does not keep the case body and shoulder in perfect alignment with its neck while sizing cannot be relied on to have good case neck-bullet alignment with its shoulder and body after it's out of the die.

 

[Alex Wheeler]

Its about impossible to measure the shoulder diam of the case at its smallest point, which is the number on the print. You almost always measure it a couple thou bigger just to get the mic on there. I doubt you will find a die manufacturer that will guarantee a resized case number. I have had good luck with redding s-dies for the most part, if they over size your shoulder send some fired cases to whidden for a custom die. Your shoulder measurements are really only good for comparative purposes. Unless your measuring on an optical comp.