Headspace gauge/resizing die question

[338winmag]

ah come on Loader 7.
My statement was to any reader. sincerely
Nothing was purposely meant towards you one bit. Some posts with just the written word but without voice can sound different then its intention.

Please accept my apology and we will move on.

 

[338winmag]

Yup stuff is expensive that is for sure. I just figure out holding off 6-8 stops to fast food in the next two months will mostly pay for the new toy, but I appreciate budgets. I am on one constantly.

 

[338winmag]

Good Points BignGreen.

I think a few words of better instruction would be very beneficial and customer worthy. One die manufacturer CS stated because of legalities, some things cannot be amplified without implication. This topic is brought up often in in-house discussions.

Oh well. Everyone have a great day. I am off to the range.

 

[7 loader]

ah come on Loader 7.
My statement was to any reader. sincerely
Nothing was purposely meant towards you one bit. Some posts with just the written word but without voice can sound different then its intention.

Please accept my apology and we will move on.

Sorry. New born in my house I'm on edge. Going now to reload and help my perspective.

 

[woods]

I have been reloading my own ammo for about 6 years now. I was taught that when setting up the full length sizing die bring the ram up with shell holder to full stroke. Also having a fired cartridge of that caliber I am reloading in the shell holder, thread the die down until it just kisses the shell. Lock down the die.

I purchased some Precision Mics from RCBS that contains the headspace gauge. I never really paid to much attention to this gauges until recently when I was reading how to set up resizing dies and I started to play with them.

I was reloading for my 243 win when I got to thinking about the resizing die. So I took a look at what was going on. According to the instructions with the gauge, a 243 gauge is set at zero for a measurment of 1.6300 inches. When I put a fired unprimed cartridge in the gauge it says that it is between .001 to .0025 under the minimum length. When I run it through the resizing die, the cartridge grows. I measured the case before and after the die and it grows about .002 to .003 inches in length.

I thought the shoulder would be pushed back. But the case gets longer.

Is there something wrong with what I am doing? Do I need to just start over with the resizing die?

Jason

Hey Jason

What you are describing sounds like a perfect illustration of what happens when you do not have the die threaded in quite far enough.

For an illustration let's use some numbers to gauge by

"0" - will be as you described when you raise the ram and adjust the die down until it hits the shell holder

"-3/4" - that is UNTHREADING the die back up off the shell holder 3/4 turn. This is usually the place where the die sizes most of the NECK but the die body has not contacted the CASE BODY

"-1/2" - the die will start to contact the case body at the pressure ring which is just forward of the case head and start to size it to the inside dimensions of the die

"-1/4" - the die sizes more of the case body and when it does it will squeeze the case body like a balloon which will start to push the shoulder up. IOW your case will get longer in the dimension from the case head to the shoulder which will cause the case to start to bind and get a "crush fit". Remember when you fire formed your case, the case expanded to the chamber walls and the "springback" (an inherent property of brass) decreased the size of the case by a miniscule (.001" or less) amount allowing the case to extract. So the case dimension from the case head to the shoulder was very close to the chamber dimensions. Even a small amount of movement forward by the shoulder will then cause the case to bind.

"0" - this is where you set your die at contact with the shell holder. The die has now sized almost the entire case body length and (again squeezing the balloon) has pushed the shoulder forward the most amount causing a noticeable crush fit

"+1/8" - lower the ram and thread the die downwards a very small amount at a time. Like 338winmag said, even a little adjustment will move the shoulder WHEN IT MAKES CONTACT. You are looking for the exact setting where your die will make this initial contact with the shoulder of cases fired in your rifle. It helps to put witness marks on your die and press

"+1/4" - this is where most instructions for typical dies like RCBS Full Length dies say to set your die for "Full Length Resizing". You may not want to set it down that far, just want to find the place where the crush fit disappears. Set your rifle up and chamber the cases after each movement of the die to see if it chambers easier. You want to set the die at the very point where the die contacts the shoulder and pushes it back the minimum amount of .001" or so for a very slight crush fit. I call this Partial Full Lenth Resizing but the terminology used amongst reloaders is not standardized so some may call it something else.

If you push the shoulder back so that it has no contact then that is Full Length Resizing in my feeble mind and if you do it repeatedly then your case life will suffer. Continual expansion to the shoulder and then setting it back more than necessary will cause the case to continually expand forward at the shoulder, grip the chamber walls and then the case head will be pushed back to the bolt face. This rubber-banding will thin and weaken the case at the pressure ring.

 

[CRNA]

Hey Jason

What you are describing sounds like a perfect illustration of what happens when you do not have the die threaded in quite far enough.

For an illustration let's use some numbers to gauge by

"0" - will be as you described when you raise the ram and adjust the die down until it hits the shell holder

"-3/4" - that is UNTHREADING the die back up off the shell holder 3/4 turn. This is usually the place where the die sizes most of the NECK but the die body has not contacted the CASE BODY

"-1/2" - the die will start to contact the case body at the pressure ring which is just forward of the case head and start to size it to the inside dimensions of the die

"-1/4" - the die sizes more of the case body and when it does it will squeeze the case body like a balloon which will start to push the shoulder up. IOW your case will get longer in the dimension from the case head to the shoulder which will cause the case to start to bind and get a "crush fit". Remember when you fire formed your case, the case expanded to the chamber walls and the "springback" (an inherent property of brass) decreased the size of the case by a miniscule (.001" or less) amount allowing the case to extract. So the case dimension from the case head to the shoulder was very close to the chamber dimensions. Even a small amount of movement forward by the shoulder will then cause the case to bind.

"0" - this is where you set your die at contact with the shell holder. The die has now sized almost the entire case body length and (again squeezing the balloon) has pushed the shoulder forward the most amount causing a noticeable crush fit

"+1/8" - lower the ram and thread the die downwards a very small amount at a time. Like 338winmag said, even a little adjustment will move the shoulder WHEN IT MAKES CONTACT. You are looking for the exact setting where your die will make this initial contact with the shoulder of cases fired in your rifle. It helps to put witness marks on your die and press

"+1/4" - this is where most instructions for typical dies like RCBS Full Length dies say to set your die for "Full Length Resizing". You may not want to set it down that far, just want to find the place where the crush fit disappears. Set your rifle up and chamber the cases after each movement of the die to see if it chambers easier. You want to set the die at the very point where the die contacts the shoulder and pushes it back the minimum amount of .001" or so for a very slight crush fit. I call this Partial Full Lenth Resizing but the terminology used amongst reloaders is not standardized so some may call it something else.

If you push the shoulder back so that it has no contact then that is Full Length Resizing in my feeble mind and if you do it repeatedly then your case life will suffer. Continual expansion to the shoulder and then setting it back more than necessary will cause the case to continually expand forward at the shoulder, grip the chamber walls and then the case head will be pushed back to the bolt face. This rubber-banding will thin and weaken the case at the pressure ring.

Woods
Thanks for this explanation. Very easy to understand. Thanks for clearing some of the mud between my ears.
Steve

 

[338winmag]

..as always great explanation woods! I luv his pictures too.
..everyone, just please keep in mind what I mentioned about the touchy-feely-turney. Even though most all these dies are same size threads, my RCBS die takes only about 1/12 - 1/16 of a turn to go from 0 to .0015.

Thanks all
338winmag

 

[boomtube]

"You are right but I tend to follow the directions From the people that designed the equipment first."

"Die directions" are not an end all. They allow noobs who don't have a clue what they're doing to make ammo that will chamber and go BOOM, but no more than that.

Given the normal slight variations in chambers, cases, presses, dies and shell holders there is no way a simplistic set of instructions can possibly explain in simple "1-2-3" steps how to properly set up a FL sizer. Doing it "right , ie, by the factory directions, will almost always make the cases too small so they WILL stretch each time they are fired.

Most bottle neck cartridges have maximum-to-minimum shoulder location variation - headspace - of about 6 thou. A "small" 1/4 turn die adjustment potentially moves case shoulders almost 18 thou, fully equal to three times the permited headspace range. Even a 1/16th turn moves the die 4.5 thou and that's more than enough change to materially affect chambering.



"In my opinion all new comers need no less than 3 books that are well read and allways back up any info from the internet with a book."

The ONLY reason a noob with a single good loading manual needs another one is for working with new cartridges or new powders and that's not a common need. Noobs with multipule manuals are NOT helped with the extras, they WILL instead be confused and lose confidence because the books always give conflicting loading data. I've been reloading since '65 and now have about 30 manuals, added less than one per year. But I only had ONE (Lyman) manual for the first five years and that didn't handicap me a bit. When I finally got my second manual I had enough experience I could intelligently deal with the conflicts.


"Head space guages will not tell you the size of your chamber after all all guns are not the same."

That's certainly true. But everyone should understand that "headspace" only applies to the chamber, not the case. We need to size our cases to match the headspace and that's fairly easy to do. The various case shoulder gages (Sinclair, Hornady, RCBS, Innovative Technoligies) allow us to match our resized cases to match the fired case shoulder location, which will be a few thou less than the actual headspace/chamber size. Actually, real headspace means nothing to a competent handloader who knows how to properly adjust his FL sizer. (And that's NOT according to the directions!)


"And also incipient separations can be caused by more than how you set your die take pressure for one."

Incipient head seperations aren't real seperations. The case stretch lines are simply the preliminary (incipient) signs of an impending real seperation. But, no matter the chamber pressure, if a case actually fits the chamber properly there will be very little stretch with each firing and the neck or body will normally split before a head seperation occurs.

 

[cornchuck]

Thanks for all the info on this subject. I know that I am going to reset all of my resizing dies.

Jason gun)

 

[cornchuck]

Again thanks for all the information that everyone has given in the subject of headspace and setting up resizing dies. I adjusted my resizing die for my .243 win today. Fired cases had resistence and when I bump them back .0002, the bolt closed easier. Now I'm going to have to readjust for my .223 and .30-06.

Jason gun)

 

[boomtube]

"... .0002, ..."

You sure? That's only .2 thousants of an inch! Not many loads would ever notice such a tiny difference!

 

[cornchuck]

Sorry!! Added too many zreo's. It should be .002 inches.

Jason gun)

 

[BountyHunter]

The problem lies in the SAAMI specs which give min and max dimensions for chambers and cartridges and reloaders not understanding what is going on.

Cartridges are always built to go in the minimum chamber and chambers are routinely set to maximum specs to ensure that all cartridges fit.

Most of the die manufacturers also build their dies for the min specs to size everything where it will fit in any chamber again. No concern is given to long case life.

You have .006 normally between a GO and NO GO guage for the caliber and then you have another .009-.010 for the normal FIELD gauge.

It is possible to have up to .015 variance between the chamber shoulder (that is also assuming it was in spec to begin with) and the cartridge shoulder for the virgin cartridge or reloaded cartridge IF you screw the die to the shellholder. That is a bottleneck cartridge and belted cases can have even more variances.

The FL dies are set to squeeze the base back to the minimum normally also and that is the arguement that the NS only advocates jump on.

Problem is that the NS method still requires either to throw the case away after 4-5 reloadings or resize it way back down and work the brass and that leaves brass that varies in body dimensions. Got to resize all brass with the same number of firings and assume that they all grow the same. That rarely happens so uniformity is in reality out the door.

Expander balls tend to drag on the necks lengthening cases and introducing runout where it may not have existed.

IMO two changes by the reloader that easily fix both issues.

1. Get rid of the expanders balls, go to a straight decapper pin in the FL die. All die manufacturers sell them. Buy an expanding mandrel to fit the necks to take out any dents if you need them.

2. Try several dies to get the best fit body (email the mftrs to get their specs for the body) or take $40-50 and have JLC Precision hone your dies or make a custom FL bushing die for ($100) to fit your chamber to give you the .001 body size that along with the .001 shoulder bump gives you a 100% reliable case that will not have case head separation and long life.

BH

 

[338winmag]

Yet another good explanation.