partial resize?


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BGD
December 28, 2012, 10:26 PM
What is the best way to just bump the shoulder back .001? Can it be done with a standard full length sizer die?

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gamestalker
December 29, 2012, 01:14 AM
Yes, the shoulder can be pushed back effectively and a FL die is designed to do just that. How far down you adjust the die will determine how far the shoulder is pushed back. The fact that a FL die also resizes the case body isn't going to be an issue as it will help to ensure clean chambering rounds.

GS

BGD
December 29, 2012, 02:43 AM
Thanks,
I thought it was a good idea to partial size to not work the brass as much. Just wasn't sure if It could be done with a full length sizer or if there was a special die needed.

Centurian22
December 29, 2012, 03:54 AM
I'm curious about this as well. I have lee dies and I was trying to adjust my FL sizing die for .308 to just bump the shoulder by marking the case neck and shoulder with sharpie then screwing it in a little at a time. I found that when the mark indicated contact with the shoulder, there was almost no distance left to screw in farther (die was almost touching the shell holder). I suppose this could be due to the brass only being once fired.

Bart B.
December 29, 2012, 12:35 PM
Folks wanting to set fired case shoulders should get a gauge to measure case headspace; distance from case head to shoulder reference. Measure a fired case then again after full length sizing. Adjust the die up or down to have it set the shoulder back no more than .002".

RCBS, Hornady and others make such tools; example the RCBS Precision Mic.

Note the amount of spring your press has plus the amount and type of lube you put on the case will result in different shoulder set back for a given position of the die. A 2 to3 thousandths spread is typical. Some case lubes are better than others in this matter; I use a 50-50 mix of STP engine treatement and Hoppe's No. 9 bore cleaner, then tumble deprimed cleaned cases in a foam line can on a Thumblers Tumbler. Sized case headspace spread is typically well under .002".

homatok
December 29, 2012, 01:38 PM
Centurian22---The position of your die (as noted) is more likely related to a die that has been produced close to SAAMI minimum specifications.

Bart B.
December 29, 2012, 02:12 PM
homatak, there are no SAAMI specs on reloading dies. The die companies all set their own specs. And a few thousandths spread from the die's bottom to the shoulder headspace reference is the norm with all the same die type and cartridge from a given company.

For example, I've got 6 RCBS standard full length .308 Win. sizing dies. None of them let their bottoms touch the shell holder when a GO headspace gauge is in the shell holder, ram at the top of its stroke and the die set so it touches the gauge's shoulder. Full length sizing a case in any one die so set does not set the shoulder back far enough to let it chamber in barrel's with SAAMI spec chambers at the same dimension of the gauge plus .0005"; 1.6305".

GLOOB
December 29, 2012, 03:14 PM
I'm curious about this as well. I have lee dies and I was trying to adjust my FL sizing die for .308 to just bump the shoulder by marking the case neck and shoulder with sharpie then screwing it in a little at a time. I found that when the mark indicated contact with the shoulder, there was almost no distance left to screw in farther (die was almost touching the shell holder). I suppose this could be due to the brass only being once fired.
It may be your rifle has a tight chamber and/or your die doesn't size quite to the min with those cases. W/e, it's a good thing. Your brass is going to last a long time, even if you FLR.

Blue68f100
December 29, 2012, 07:11 PM
Foster makes a special die to neck size and bump the shoulder back.

http://www.forsterproducts.com/store.asp?pid=27654

Walkalong
December 29, 2012, 08:09 PM
Folks wanting to set fired case shoulders should get a gauge to measure case headspace; distance from case head to shoulder reference. Measure a fired case then again after full length sizing. Adjust the die up or down to have it set the shoulder back no more than .002".

RCBS, Hornady and others make such tools; example the RCBS Precision Mic.

Note the amount of spring your press has plus the amount and type of lube you put on the case will result in different shoulder set back for a given position of the die. A 2 to3 thousandths spread is typical. Some case lubes are better than others in this matter; I use a 50-50 mix of STP engine treatement and Hoppe's No. 9 bore cleaner, then tumble deprimed cleaned cases in a foam line can on a Thumblers Tumbler. Sized case headspace spread is typically well under .002".
This.

Trying to size to the nearest .001 consistently is a bit optimistic. On my home made log book where I record the shoulder measurement, I either write down the spread, or the average, and mark it as such. Not to mention the brass does not fully fill the chamber on the first firing, nor the second usually.

Walkalong
December 29, 2012, 08:12 PM
Foster makes a special die to neck size and bump the shoulder back.I just bought one of those (http://www.thehighroad.org/attachment.php?attachmentid=176290&d=1355794205) to try in .308, and it seems to work very well. Not much to go on yet though.

homatok
December 30, 2012, 02:30 PM
Poor choice of wording on my part! Gloob expressed what I was thinking at the time!

Centurian22
December 31, 2012, 06:00 AM
Thanks for the input and replies. Gloob, hope you're right about my brass life, that will be nice.

sage5907
December 31, 2012, 02:17 PM
I use a RCBS precision micrometer that was mentioned by Bart B. With this micrometer you take a case that is fire formed to your rifle chamber and then slowly screw the resizing die down until it pushes the shouder back about .002. .002 is more realistic than .001 because of the spring back in each separate case and other factors that cause the cases to measure differently after they have been sized. Remember that new cases may be as much as .006 shorter than your chamber and it may take more than one firing before they expand to the full length of your chamber.

fguffey
January 15, 2013, 01:50 PM
I fire a case, when I fire a case it gets hammered, my hammered cases have no memory of what they were before I fired them. My cases are full grown after firing them the first time. I have fired 8mm57 ammo in an 8mm/06 chamber, when ejected the case took on the appearance of an 8mm/06 without a neck and short shoulder. 308 Ws have been fired in 30/06 chambers, same thing, the 308 W case, when ejected had no neck and only a hint of a shoulder, I could have placed the cases in a safe place and waited, no amount of spring back, jump back or snap back was going to allow those cases to recover.

“partial resize?

--------------------------------------------------------------------------------

What is the best way to just bump the shoulder back .001? Can it be done with a standard full length sizer die?”

The best way is to understand the dynamics of sizing, the case is tapered, the case is round, means nothing to a reloader but a taper that is round is a cone, the body of the chamber is a cone, the case body is a cone, the case body of the die is a cone, the answer to your question is ‘YES’, I can use a full length sizer die to place the shoulder where I want it, ‘NO’ I can not bump it because of the cone, when I size a case I use lube, lube reduces case resistance to sizing, when sizing the first part of the case that hits the die is the neck, then the case body, after the case body contacts the die the shoulder of the case contacts the shoulder of the die. When the shoulder of the case comes in contact with the die the case is not full length sized as in raising the ram until the full length sizer die comes in contact with the shell holder..

The case is not full length sized until the die contacts the shell holder, if I want to know how much of the case that did not get sized I measure the gap between the top of the shell holder and bottom of the die before lowering the ram ‘BECAUSE’ the only thing that is preventing the die to shell holder contact is the case. Back to cases not being full grown, multi firing of a case work hardens the case and increases resistance to sizing, then there is the Shadow Factor, Who knows what happens to the action then it is hammered with thousands of pounds of pressure, my opinion, getting hit with 50,000 psi is no buggy ride, then there is stretch and flexibility of metal, and memory, metal that is hard and does not flex brakes.

I understand the tough part of sizing comes when the reloader attempts to return the case to minimum length/full length size. With my 30/06 type cases that is at least .005” I do not insist on full length sizing therefore I do not insist on screwing the die down to the shell holder with the ram up then screw the die down an additional 1/4 or .017”, depending it I am using fractional turns of the die or degrees converted to thousandths. Either way I would need to verify, I use the verifying tool, the feeler gage, the companion to the press, the feeler gage to verify, so, instead of making all the wild guestimates of a turn in fractions and or degree converted to thousandths, I go straight to the verifying tool, the feeler gage.

I can not move the shoulder .001” without moving the cone of the die back, moving the cone of the die back (down) sizes the case body, there is no other way to but it, the bump die can not bump the shoulder with out case body support, no, it is not bumping, it is sizing, there is the cone, the cone is created when the sides are tapered and the the taper is round. I have 270 cases, I have 30/06 sizing dies, If I choose I can use the 30/06 sizer die to size a 270 Winchester die, seems to me It could be said I turned a 30/06 sizing die into a 270 Winchester bump die, then there is the 308 W sizer die being used on the 7MM08 case to bump??? again, if the shoulder is being bumped the case body must be supported or the shoulder case body juncture will expand.

I do not over work (abuse) my press, I do not insist the die contact the shell holder at the top of the ram travel.

F. Guffey

fguffey
January 15, 2013, 02:05 PM
“Remember that new cases may be as much as .006 shorter than your chamber”

I remember two measurements, one is case length as in the .006” you refer to, then there is the other dimension/measurement, that is the one that is taken from the bolt face to the shoulder of the chamber, then there is the other measurement, the one taken from the case head to the shoulder of the case. I am a multi task-er, keeping up with all three does not drive me to the curb.

Cases shorten when fired for different reasons, I have never experienced a case shortening (getting shorter) from the head of the case to the shoulder, I have experience cases shortening .040”, one of those twilight zone things, the case lengthened from the head of the case to the shoulder and at the same time the neck got shorter, same thing happened to Hatcher, he did not scribe his case, back to never, I have never had a case to shorten between the head of the case to the shoulder and that makes the statement about firing 4 times to full grow a case put in in the category of “Once upon a time” or “You are not going to believe this...” or “Listen-up men”, like the stories of the Brothers Grimm and Mother Goose, it just did not happen.

F. Guffey

fguffey
January 15, 2013, 02:25 PM
Again, the recommendation from reloading forms goes something like this “Purchase a head space gage’, always left out is the head space gage is a transfer, it is a standard, a reloader can remove the sizer ball/primer punch assemble to check the ability of a full length sizer die to restore a case to minimum length/full length size, depending on the die the 30/06 full length sizer die should be .005” shorter from the deck of the shell holder to the shoulder of the of the die, THAT IS GO-GAGE LENGTH and the reason for the gap.

It is not necessary to install the die and shell holder, just simply stack them with the gage installed in the shell holder then measure the gap between the top of the shell holder and bottom of the die, PROBLEM? Most go-gages will not fit a shell holder, back to no problem instead of using a #3 shell holder for the 30/06 family of cases use a 300 Win Mag #4 shell holder, reminder, the deck height of the shell holder is .125”, meaning it would not matter which shell holder was used.

“then measure the gap between the top of the shell holder and bottom of the die” with a feeler gage, the companion tool to the press, the feeler gage. And when the case does not get stuffed into the die when the ram is raised the amount of case that does not get sized can be measured with a feeler gage, the gap between the die and top of the shell holder.

F. Guffey

greyling22
January 15, 2013, 02:36 PM
centurion, my bolt action 223 has a tight chamber and my lee dies don't quite resize enough for it. The bolt is pretty hard to close. Factory ammo drops right in. My cases are dragging back by the case head.

I talked to a guy at lee and what I understood of what he said was that most factory ammo is loaded small enough that it will fit the tightest samii chamber. Possibly even slightly outside samii specs on the small side. Regardless, he said that if I mailed them the sizing die, a fired case from my chamber, and a unfired factory round that they would tinker with my die until my cases went in smoothly. I haven't done it yet because well, my brass isn't getting worked as much and lee is backed up.

fguffey
January 15, 2013, 02:40 PM
Forgive/forgot: Back to the “Purchase a head space gage”, always left out, the go-gage is a standard, the go-gage is a transfer, the Wilson case gage can be checked for accuracy. simply drop the head space gage into the Wilson case gage and measure go-gage head protrusion, again, use a straight edge, or a pocket rule or a height gage or a dial caliper with all in one height gage built in or a flat surface like a set up table and the companion tool to the press, the feeler gage. With the Wilson case gage supported by the go-gage measure the gap between the flat surface/set up table and Wilson gage. remember the Wilson case gage uses a datum, not a shoulder, the datum has a radius.

I need a datum I make it, if I do not know the datum I make one up. or, I use a used one.

F. Guffey

fguffey
January 15, 2013, 02:56 PM
Grayline, I measure the length of new ammo from the head of the case to the shoulder because I am a reloader, if new, factory, store purchased ammo chambers I need to know the distance/length of the case from the head of the case to the shoulder for comparison, if my sized cases will not chamber I need to know why and I need to know the difference in length between my new ammo that would chamber and my resized cases. I have been told I am the only reloader that measure new ammo that will chamber.

If I talk to a technical person that blames someone else I ask to talk the other technical person.

I size cases for short chamber, I size cases for long chambers, the spread in thousands for the 30/06 family of cartridges is .028 thousands from –.012 to +.016” as in .012” shorter than a minimum length sized, new, over the counter factory load to .016” longer than minimum length.

I jack up the case off the deck of the shell holder with a feeler gage, I also use a feeler gage to determine if the die made it down to the shell holder, again, if the die is not contacting the top of the shell holder, the case whipped the press, I have presses that have a guarantee, they will not flex, to use one I am forced to remove another press to make room.

F. Guffey

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