BUSHING DIES: have I understood the workflow correctly

[tikkathreebarrels]

I'm about to start using bushing dies for the first time though I have years' of experience of the non-bushing type. I want to be sure I've got the workflow clear in my mind.
This is what my Sinclair catalogue says on the Redding page about "Determining Redding Bushing Size":

"The proper bushing size can be easily determined by measuring the outside neck diameter of your loaded cartridges with a precision micrometer or dial caliper . Then, simply subtract .001" from the cartridge that has the smallest average neck diameter. This diameter bushing will generally size case necks just enough to create the proper press fit for the bullet."

Question 1: the mandrel which carries the decapping pin is smaller diameter than the case neck which tells me that the mandrel is not designed to support the inside of the case neck whilst it is being compressed by the die but is there simply as a carrier for the decapping pin. Beyond that it plays no part in the resiizing process: yes?

Question 2: Is it more worthwhile to take the measurement on new cases or on cases which have been fired through the rifle?

Bearing in mind that this is a factory rifle with a factory chamber, I don't expect to be dealing with a "tight neck" chamber where clearances between chamber and case neck are critical.

Question 3: The instruction reprinted above in italics: it doesn't seem to acknowledge that the "loaded rifle cartridge" could have been loaded with more or less neck tension in the first place. So, if we're starting from a random place, surely all the bushing die is doing is creating repeatability of that randomly acheived neck tension.

 

[see it shoot it]

I'm about to start using bushing dies for the first time though I have years' of experience of the non-bushing type. I want to be sure I've got the workflow clear in my mind.
This is what my Sinclair catalogue says on the Redding page about "Determining Redding Bushing Size":

"The proper bushing size can be easily determined by measuring the outside neck diameter of your loaded cartridges with a precision micrometer or dial caliper . Then, simply subtract .001" from the cartridge that has the smallest average neck diameter. This diameter bushing will generally size case necks just enough to create the proper press fit for the bullet."

Question 1: the mandrel which carries the decapping pin is smaller diameter than the case neck which tells me that the mandrel is not designed to support the inside of the case neck whilst it is being compressed by the die but is there simply as a carrier for the decapping pin. Beyond that it plays no part in the resiizing process: yes?

this is true,I remove my pin as I prefer to remove the primer using a different die

Question 2: Is it more worthwhile to take the measurement on new cases or on cases which have been fired through the rifle?
in my experience of using these dies for many years measure the wall thickness of your cases get the average the double it and add the bullet dia then subtract 2 thou


Bearing in mind that this is a factory rifle with a factory chamber, I don't expect to be dealing with a "tight neck" chamber where clearances between chamber and case neck are critical.

Question 3: The instruction reprinted above in italics: it doesn't seem to acknowledge that the "loaded rifle cartridge" could have been loaded with more or less neck tension in the first place. So, if we're starting from a random place, surely all the bushing die is doing is creating repeatability of that randomly acheived neck tension.

yes it will be repeatable on all your brass once you have found the most suitable bushing size,

 

[jcampbellsmith]

This is an interesting article relating to your questions and worth a read.

http://riflemansjournal.blogspot.co.uk/2009/10/reloading-neck-tension.html

At present I don't use the expander ball when using a bushing die, however as in many of these questions, there are different opinions on what's best. I've ended up with a set of about a dozen different bushings in order to deal with different brands of brass and different chamber sizes.

I use a decapping die to deprime the cases, then clean them, then resize and trim, before a final clean.

Regards

​JCS

 

[Selous]

Is the idea behind removing the decap ping pin from the size die to reduce working the neck or to improve concentricity?

 

[Ronin]

Decap rod only does that - no re working of the brass internally.

Selecting bushing for a factory chamber measure the diameter of fired brass.

This will give you an indication of how large the chamber is (at the neck)

Measure the inside diameter of the brass too

You can then work out what bushing to buy

Example - Factory 308

Fired brass at neck measures .343"

Inside neck Diameter (fired) - .310"

Bullet dimeter - .308"

So to get a slip fit - i.e.; zero neck tension, you would need to resize the brass .002"

To get .002" tension you would need to resize the brass .004"

Therefore using the original outside diameter of the fired brass (.343") and take away .004" will give a bushing diameter of .339" to give .002" neck tension on resized brass.

This method works for me in factory chambered rifles, where I use bushing dies, it wont overwork the brass or create an unsightly and heavily swaged case neck around the seated bullet (as one sees in some factory die sets)


Hope that helps

 

[Ronin]

Simon,

​Yes,

easier to have separate decap die and remove the internal mandrel on the die - its not necessary and overworks the brass

 

[tikkathreebarrels]

This is an interesting article relating to your questions and worth a read.

http://riflemansjournal.blogspot.co.uk/2009/10/reloading-neck-tension.html

At present I don't use the expander ball when using a bushing die, however as in many of these questions, there are different opinions on what's best. I've ended up with a set of about a dozen different bushings in order to deal with different brands of brass and different chamber sizes.

I use a decapping die to deprime the cases, then clean them, then resize and trim, before a final clean.

Regards

​JCS

Thanks for the link: I'll have a good read.

Decap rod only does that - no re working of the brass internally.

Selecting bushing for a factory chamber measure the diameter of fired brass.

This will give you an indication of how large the chamber is (at the neck)

Measure the inside diameter of the brass too

You can then work out what bushing to buy

Example - Factory 308

Fired brass at neck measures .343"

Inside neck Diameter (fired) - .310"

Bullet dimeter - .308"

So to get a slip fit - i.e.; zero neck tension, you would need to resize the brass .002"

To get .002" tension you would need to resize the brass .004"

Therefore using the original outside diameter of the fired brass (.343") and take away .004" will give a bushing diameter of .339" to give .002" neck tension on resized brass.

This method works for me in factory chambered rifles, where I use bushing dies, it wont overwork the brass or create an unsightly and heavily swaged case neck around the seated bullet (as one sees in some factory die sets)


Hope that helps

So bearing in mind that 7mm WSM isn't exactly on every RFD's shelves I need to knock up some "safe" unmeasured neck rounds, shoot 'em and then measure up for optimal bushing?

yes it will be repeatable on all your brass once you have found the most suitable bushing size,

Suitable. Oh yes, that's what I'm looking for.

 

[Ronin]

In essence yes

I shoot a variety of 7 WSM's......

Ive got numerous bushings too - let me know what size you work out, I may have it spare

Ive also made my own bushings, thats an option if you cant find what you want off the shelf here, though they are available in 7-10 days from Sinclair international

 

[Milligan]

I'm about to start using bushing dies for the first time though I have years' of experience of the non-bushing type. I want to be sure I've got the workflow clear in my mind.
This is what my Sinclair catalogue says on the Redding page about "Determining Redding Bushing Size":

"The proper bushing size can be easily determined by measuring the outside neck diameter of your loaded cartridges with a precision micrometer or dial caliper . Then, simply subtract .001" from the cartridge that has the smallest average neck diameter. This diameter bushing will generally size case necks just enough to create the proper press fit for the bullet."
Individual results may vary. Redding stated 2 thou, then changed to 1.

Question 1: the mandrel which carries the decapping pin is smaller diameter than the case neck which tells me that the mandrel is not designed to support the inside of the case neck whilst it is being compressed by the die but is there simply as a carrier for the decapping pin. Beyond that it plays no part in the resiizing process: yes?
Correct, serves no purpose. I think Redding bushing dies come with an expander ball and a decapping holder.

Question 2: Is it more worthwhile to take the measurement on new cases or on cases which have been fired through the rifle?
Measure loaded rounds and subtract from that. 1 thou is a starting point, I found 2 thou worked better in my .260.
Also, brass thickness varies from manufacturer to manufacturer so expect to have to have a number of bushings when dealing with multiple makes.

Bearing in mind that this is a factory rifle with a factory chamber, I don't expect to be dealing with a "tight neck" chamber where clearances between chamber and case neck are critical.

Question 3: The instruction reprinted above in italics: it doesn't seem to acknowledge that the "loaded rifle cartridge" could have been loaded with more or less neck tension in the first place. So, if we're starting from a random place, surely all the bushing die is doing is creating repeatability of that randomly acheived neck tension.
Doesn't matter what tension you started with, the OD of the brass loaded is a function of the bullet and the neck wall thickness.

Enjoy bushings...

 

[Ronin]

Theyre simple.


​

 

[Whitebeard]

Threebarrels,
Unless you are loading extremely high quality brass which has very consistant neck thickness such as Lapua, RWS or Norma, bushing dies will not give you consistant neck tension unless you neck turn, even with the above brass inconsistancies can occur without neck turning.

Ian.

 

[jay 22]

Threebarrels,
Unless you are loading extremely high quality brass which has very consistant neck thickness such as Lapua, RWS or Norma, bushing dies will not give you consistant neck tension unless you neck turn, even with the above brass inconsistancies can occur without neck turning.

Ian.

yup i agree. when i had a 17 rem fireball built i was close to buying a bushing die from the usa. but with the poor remmy brass the only option for that calibre. it wasn't worth the bother

 

[tikkathreebarrels]

Threebarrels,
Unless you are loading extremely high quality brass which has very consistant neck thickness such as Lapua, RWS or Norma, bushing dies will not give you consistant neck tension unless you neck turn, even with the above brass inconsistancies can occur without neck turning.

Ian.

yup i agree. when i had a 17 rem fireball built i was close to buying a bushing die from the usa. but with the poor remmy brass the only option for that calibre. it wasn't worth the bother

You guys: you're nicely summing up my initial thoughts. I've inherited this gear with the rifle and the brass. The chambering is new to me but left to my own devices, I'd have gone in a different direction with the dies. Whether 7mm WSM is a long term commitment for is is way too early to tell but bearing in mind I'm talking about a factory sporter rifle the matter of squeezing every last bit of accuracy out of the rig is a bit academic: I'll hope to get the best I can out of it without expecting custom rifle benchrest results. Interesting though.

For now then: measure and sort this brass for neck thickness and if it's a bit wild invest in a box of new shiny brass.

 

[bewsher500]

its not just thickness that affects tension
variance in brass hardness is much more significant IMO

when you seat a bullet you are resizing the neck with the bullet.
give or take a thou/hundred thou you will always get a bore 1-2 thou less than the diameter of the bullet if you seat and remove

but work hardened brass will not spring back anything like as well and can cause major issues

​

 

[Muir]

What were you using that performed so badly that you felt compelled to enter into the neck bushing fray?? Or is it a custom build, or a wild cat??~Muir

 

[Whitebeard]

its not just thickness that affects tension
variance in brass hardness is much more significant IMO
​

bewsher, i doubt very much that you will get much brass hardness variences within a batch of the same brass, when all have recieved the same amount of reloading cycles.

Ian.

 

[tikkathreebarrels]

What were you using that performed so badly that you felt compelled to enter into the neck bushing fray?? Or is it a custom build, or a wild cat??~Muir

Who me? I simply bought a used rifle and the various reloading items which the seller was parting company with.

 

[Muir]

Who me? I simply bought a used rifle and the various reloading items which the seller was parting company with.

Got it.~Muir

 

[bewsher500]

bewsher, i doubt very much that you will get much brass hardness variences within a batch of the same brass, when all have recieved the same amount of reloading cycles.

Ian.

you are assuming everyone is shooting batched brass with counted cycles

I bought a suposed batch of "once fired" lapua and had precisely that issue
half of them wouldn't obturate and others were fine, some were inbetween

 

[Whitebeard]

you are assuming everyone is shooting batched brass with counted cycles

I bought a suposed batch of "once fired" lapua and had precisely that issue
half of them wouldn't obturate and others were fine, some were inbetween

I have never and will never buy once fired brass!

Ian.