Brass Lengthening in FL Sizing Die

[David Christian]

All,
I am having a frustrating issue reloading and was hoping someone here could give me a little help.

Right now I am doing load development and barrel break in for a new rifle, and have fired my first 100 pieces of Lapua brass once.
After decapping and tumbling them, I'm running into issues resizing.

I'm trying to full length resize and bump my shoulder back ~.002", which seems simple enough.
My resizing die is a Redding S series, full length sizer. It has a neck bushing and the mandrel is removed.

After resizing, cases are consistently measuring .004-.005" LONGER than when they started, which seems impossible.
This is measured on a set of Starrett calipers that I know to be accurate, using a shoulder bump gauge that measures at mid shoulder - not OACL.

My press is a Forster Coax, and the die is as far down as is physically possible while still being able to cam over the press; it takes some noticeable effort. I can't lower it any further.

The die is also leaving a weird ring or distortion about mid-shoulder on the resized cases, which is easier to see in person but I did include a photo.

Needless to say this is perplexing. I feel like my dies, press, and method are 'good', and my measuring devices are telling me the truth, I just cannot see how this is occurring.
The resized cases will chamber, which also seems strange.

First photo is 1x fired, untrimmed brass - just decapped and cleaned. 2nd is after resizing, 3rd is the distortion the die is leaving on the shoulder. View attachment 1561741View attachment 1561742View attachment 1561743

**I am not using WD40 as lube, the can is just in the background. Imperial sizing wax, used as directed.

Does the sized brass chamber?

 

[rlporter507]

Not sized enough to set the shoulder back, that could be the weird ring you see, its just starting to move brass there. I've had to take a few thousands off many shell holders to get the set back I wanted. Post 8. Easy on a lathe, but takes longer with sand paper on a flat surface. Also could be the expander ball pulling the shoulder out caused by to small a bushing or not enough lube.

 

[Kracken McGraw]

I don’t know how it does it but using the Redding competition shell holders, I have had it lengthen before sizing it down when dropping to the lower number shell holders.

 

[David Christian]

I don’t know how it does it but using the Redding competition shell holders, I have had it lengthen before sizing it down when dropping to the lower number shell holders.

That is exactly what happens every time you resize brass. The body is squeezed in, which lengthens the overall case before the shoulder is compressed and pushed back.

I am waiting to hear back from the OP on if his sized brass will chamber. If not, shaving the die or shell holder will be needed.

 

[Will Henry]

Virtually all "stretching" of brass occurs during the full length sizing operation. It is unavoidable. The amount of elongation will be dependent on the dimensions of the chamber, the dimensions of die, and to a lesser extent, the shape of the case.
If a new piece of brass is fired in a chamber with zero head clearance, the brass will expand outwards until it contacts the chamber wall. When it does this, the length of the brass will often shorten up a little bit. Again, the amount of change in dimensions will be dependent on the difference in dimensions between the chamber and the cartridge. When this piece of brass is then shoved into a FL sizing die, the brass which stretched out does not get put back to where it came from. Instead, as the circumference is reduced the case lengthens. Now, I'm not saying all of the brass squirts forward, but a significant portion of it does. Upon firing again, the cycle is repeated.
The shape of the case, mostly the shoulder angle, can help to put the brass back where it came from, but not a lot.
In a solid front locking action, in a rifle with minimal head clearance, brass stretch from firing is essentially zero. If the case is neck sized, the neck will lengthen. Again, the amount of stretch is entirely dependent on the amount of sizing. With no sizing, the case does not lengthen. By the way, collet dies do better in this regard. WH

 

[savageshooter86]

the OP isn’t saying the OAL of case is growing like
some comments are trying to correct for or explain. His shoulder measurement is. So I believe the die isn’t set up properly and isn’t down far enough to push shoulders back like he is wanting. I have seen this before when I initially set up a FL die. They got longer until die was set to contact shoulder and bump them back

 

[Will Henry]

Yes, with a FL die, the shoulder does move ahead until contact is made. Again, this has a lot to do with case and chamber dimensions in relation to die dimensions. The amount of body taper can also play a part. I can size 2/3 of the neck before the body gets sized much in my 30/40 Krag. I can't do this with the 308 Norma. My 6.5CM allows for partial sizing because the chamber and die dimensions are very compatible. WH

 

[Walt Krafft]

OP has not been back to see any responses to his problem.

 

[gunsandgunsmithing]

As others have said, the case gets longer in the die UNTIL the die comes into contact with the shoulder, then starting to bump the shoulder back. That's normal but you'll likely need to remove some material from either the bottom of the die or the top of the shell holder to fix it. You can try running it down a bit further to see if you gain any sizing first...a little more cam over. Another option is simply deepen the chamber a few thou. Dead on minimum go gauge chambers actually cause more problems than they have ever cured. A couple of thou over a go gauge is usually enough and is still within spec, between a go and a no go.

 

[243winxb]

My press is a Forster Coax

No shell holder.

OP - Last seen Thursday at 10:18 PM

 

[gunsandgunsmithing]

No shell holder.

Same deal, but it'll need to either come from the die or the chamber, then.

 

[3498D]

I appreciate everyone's replies, I've been super busy with work and projects on the house.
Unfortunately I haven't had a lot of time to get back to the reloading bench, or get a response put together here.

I've read everything that was contributed, and I think put together a plan based on all the information.

To answer a few pertinent questions - yes, a 1x fired case (zero trimming or resizing done to it) will still chamber, and fairly easily. Perhaps not quite as easy of a bolt throw as a brand new case, but not even close to a herculean effort.
Additionally, 1x fired case necks are tight enough to accept a bullet without any resizing. Essentially I believe I could take one of these cases and after tumbling it, chamfer the mouth prime/dump powder/seat a bullet and it would fit the chamber with zero additional work.

The reason I am trying to push back the shoulder is truthfully because...that's the done thing? A lot of people more experienced and successful than me in the shooting sports include it as part of their process, so I am as well. I've never heard anyone suggest that resizing with a ~.002 shoulder bump not be done with each firing.

It seems like my chamber is cut/headspaced in such a way that it might take a few firings before the brass is long enough for the die to actually engage the shoulder and put it back.
The diagram someone shared makes sense for why the measurement at the shoulder would be getting longer if the die isn't engaging at the right point.

Some people have asked and some have correctly pointed out - the die cannot be engaged any further in my press, it's as far down as it can go. If necessary I could shave off a few thousandths from the end of the die, but I will hold off on that for now.

JFrank said that I should put the calipers away and reload/shoot until the brass NEEDS to be resized to fit the chamber, and at this point it seems like sound advice unless someone disagrees.
If I shoot to the point that it won't chamber, but the die still won't bump the shoulder properly, then I can look into modifying the die if necessary.

Finally - cartridge is 6.5x47L, in a Borden action. Jim did the barrel chambering so I feel like all of that is done to top quality standards and isn't the issue.

Thank you again everyone.

 

[Sandstorm]

Yep..fire them again and then resize as required...Im on the same page with Jim
as long as they chamber without effort.

 

[rlporter507]

I would take some off the shell holder instead of the die first. its hard to get all the burrs off the die and it will scratch up the brass pretty good. watch at about 26 minutes in

 

[3498D]

I would take some off the shell holder instead of the die first. its hard to get all the burrs off the die and it will scratch up the brass pretty good. watch at about 26 minutes in

The Forster co-ax does not have the usual removable shell holders like a rock chucker; it's two spring loaded sliding plates that come together to hold a wide variety of cartridge sizes. I have never looked at them to see how crucial their thickness is to the function of the system since modifying them never crossed my mind.
However, making any alterations whether it be the die or the press/shellholder is not something I intend to do unless it's a last resort.

 

[Webster]

You must be using a mandrel. Make sure the brass length is measured AFTER using the mandrel. The length shrinks several thou after the mandrel. I can't see anything in the picture to worry about.

Always wondered if a mandrel pushes the shoulder slightly concave when sizing the neck. Seems that if you push hard with a mandrel the weakest part would be to push the shoulder a little concave. The body shoulder junction should be strong and resist movement?

 

[Bill K]

Try sizing without the expander on the shaft, or take it out. Could be so tight it is pulled the neck up when you lower the ram, since you said you feel hard pull back.

 

[CJ6]

Try sizing without the expander on the shaft, or take it out. Could be so tight it is pulled the neck up when you lower the ram, since you said you feel hard pull back.

The reason I went to bushing dies with no expander.

 

[Dolomite]

If your die doesn't match your chamber it maybe oversizing the body and the SBJ. example I tried a redding FL bushing die and it sized the SBJ smaller than a whidden die by about .002, which makes the brass grow in OAL. If you are using a standard FL die it sizes the brass even smaller which contributes to the OAL growth.

If your die closely matches the chamber after so many firings the body and the SBJ should only be sized down about .001-.002 max which contributes to minimum sizing and less brass growth. Brass should last longer with minimum sizing unless you are hot rodding the case.

 

[barefooter56]

All,
I am having a frustrating issue reloading and was hoping someone here could give me a little help.

Right now I am doing load development and barrel break in for a new rifle, and have fired my first 100 pieces of Lapua brass once.
After decapping and tumbling them, I'm running into issues resizing.

I'm trying to full length resize and bump my shoulder back ~.002", which seems simple enough.
My resizing die is a Redding S series, full length sizer. It has a neck bushing and the mandrel is removed.

After resizing, cases are consistently measuring .004-.005" LONGER than when they started, which seems impossible.
This is measured on a set of Starrett calipers that I know to be accurate, using a shoulder bump gauge that measures at mid shoulder - not OACL.

My press is a Forster Coax, and the die is as far down as is physically possible while still being able to cam over the press; it takes some noticeable effort. I can't lower it any further.

The die is also leaving a weird ring or distortion about mid-shoulder on the resized cases, which is easier to see in person but I did include a photo.

Needless to say this is perplexing. I feel like my dies, press, and method are 'good', and my measuring devices are telling me the truth, I just cannot see how this is occurring.
The resized cases will chamber, which also seems strange.

First photo is 1x fired, untrimmed brass - just decapped and cleaned. 2nd is after resizing, 3rd is the distortion the die is leaving on the shoulder. View attachment 1561741View attachment 1561742View attachment 1561743

**I am not using WD40 as lube, the can is just in the background. Imperial sizing wax, used as directed.

Dies and chambers all have a specification range per SAAMI. If your chamber is to the SMALL END of these specs. And your FL DIE is to the LARGE END of these specs this can happen. The only fix is to either adjust the FL DIE to a " cam over" situation. OR have .001 to .002 OF THE BASE OF THE DIE REMOVED. BY A GUNSMITH. However, this can also happen due to the brass being not completely fire formed to the chamber ! To properly set up the die I suggest you fire a cartridge case to the point where it either will not chamber or chambers hard using a stripped bolt ( no ejector or firing pin) and ADJUST THE DIE DOWN SLOWLY UNTIL THE ROUND CHAMBERS MEASURING THE SHOULDER DATUM LINE TO CARTRIDGE CASE BASE AT EACH STEP. General rule of thumb is: TARGET RIFLES .001-.002 bump, HUNTING RIFLES .002 TO .003, and SEMI -AUTO, LEVER ACTION AND PUMP ACTION RIFLES .003-.005.