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Redding Competition Shellholder / Whidden Die / Zero Press

scyzer

Looking for some help.

I’ve been chasing my tail a bit trying to minimise headspace variation when bumping back the shoulders of my brass.

With my Whidden FL Click-Adjust sizing die and my old Co-Ax press, I often found I was getting +/- 1 thou variation in headspace with a reasonable percentage of cases exhibited +/- 2 thou (ie a 4 thou range).

I anneal with my AMP every firing. My batched Lapua brass is all neck turned and exhibit low and the same number of firings.

Pre-sizing, the brass measures a very very consistent headspace measurement (within 0.5 thou).

I chalked this up to potential variations in lubrication of the brass and potential deflection issues with the floating nature of the coax press and die system.

Since then, my very lovely fiancée got me a Zero Press and I’ve tried to subscribe to the die/shellholder contact philosophy using Redding Competition Shellholders.

I’ve set up the die with the ram of the press in the upper most position having screwed the die down all the way until contact is made. With the ram lowered a touch, I turned the die in a further 1/4 turn. With the ram and shell holder pressing against the die again (with some pressure), I’ve locked the die rings down.

Without any brass in the shell holder, I can consistently get no gap contact between the shell holder and the die. However, the first issue I encountered is that once brass is inserted, even with significant pressure, there is a slight gap between the die and the shellholder. I can see light through this gap.

Before trying to diagnose the headspace issue further - is there a reason why the gap exists? If it is an issue - what’s the next step in diagnosing the problem?

Thanks!
 
how does the brass measure in the new setup? it may be alright
 
I have setups with .004 clearance, another that sizes perfectly at .007 and yet another with measured excessive cam over that now uses a reduced shell holder under .125, non require comp shell holders. I stopped trying to use razor thin margins when setting headspace and my rifle is happier as well as myself.
 
Last edited:
I use an old.sloppy RCBS partner for 6ppc loads. I do use some cam-over. I always double bump for spring back. I have another partner that I use for other loads and am waiting for it to wear a little more before moving to benchrest loads
 
When we force a case into a die, the most repeatable baseline is when the shell plate contacts the die. There is no law that says you have to, but it is a way to investigate a baseline for the sizing process that eliminates the largest possible contributor to variations.

For practical discussion, when the shell plate hits the die, there is no variation in the position of the process. That places the forced strain to what we would call a zero variation or less than what you could measure between the tools.

It isn’t impossible to set up a process that has a gap between the shell holder and die yet yields sizing that stays within control, but that requires the stiffness of the press linkages to be very high so that the scatter in the friction and cold working doesn’t end up creating scatter in the results.

Clearly there have been lots of very accomplished shooters who don’t make hard contact between the shell plate and die in their sizing process.

You should look for issues like the ones that have been mentioned above where something like a decapping stem prevents the die from controlling the process Or if the brass hasn’t finished fully flowing to the chamber and die.

If you want to try a good baseline to see the potential of your brass, lube, and dies, then I suggest you close down on the incremental shell holders and see what results, then decide on how to go forward. I have used both methods, but the easy button is hard contact to the shell holder if you want to see the repeatability potential of your tools and brass.

Leaving a gap requires higher technique and discipline compared to a positive mechanical stop for the ram or the shell holder. YMMV

Merry Christmas and Happy New Year!
Go JWST!
 
RegionRat said:
When we force a case into a die, the most repeatable baseline is when the shell plate contacts the die. There is no law that says you have to, but it is a way to investigate a baseline for the sizing process that eliminates the largest possible contributor to variations.

For practical discussion, when the shell plate hits the die, there is no variation in the position of the process. That places the forced strain to what we would call a zero variation or less than what you could measure between the tools.

It isn’t impossible to set up a process that has a gap between the shell holder and die yet yields sizing that stays within control, but that requires the stiffness of the press linkages to be very high so that the scatter in the friction and cold working doesn’t end up creating scatter in the results.

Clearly there have been lots of very accomplished shooters who don’t make hard contact between the shell plate and die in their sizing process.

You should look for issues like the ones that have been mentioned above where something like a decapping stem prevents the die from controlling the process Or if the brass hasn’t finished fully flowing to the chamber and die.

If you want to try a good baseline to see the potential of your brass, lube, and dies, then I suggest you close down on the incremental shell holders and see what results, then decide on how to go forward. I have used both methods, but the easy button is hard contact to the shell holder if you want to see the repeatability potential of your tools and brass.

Leaving a gap requires higher technique and discipline compared to a positive mechanical stop for the ram or the shell holder. YMMV

Merry Christmas and Happy New Year!
Go JWST!
Click to expand...
Last time i checked a case bump with a die hitting the shellholder it was .008 bump. Ive seen them bump .012 with some shellholders. I agree its the most consistent but if you cant use it then its no good
 
243winxb said:
It is an issue. Cam over on my RCBS press takes care of this.

No cam over? Lube with RCBS 2 on a pad. Push harder. Or turn die down more.

Maybe Read the die Instructions again?

Flex in the press?View attachment 1302032
Click to expand...

I do feel the cam over - but for some reason it just won’t get rid of the gap. I will double check for flex in the setup given I have it mounted using a inline fab quick change plate. Perhaps I didn’t torque the bolts down hard enough.
 
Dusty Stevens said:
I cant imagine your headspace is correct with your die bumping 1/4 turn. Throw the die instructions away and study around here how to setup a die for proper bump and headspace
Click to expand...

Thanks - I’ve tried to use the Redding Competition Shellholders and die contact in lieu of the other approach where you dial in bump based on rotating the die in and out and leaving a certain gap to achieve the right bump.

Clearly im doing something wrong though…
 
RegionRat said:
When we force a case into a die, the most repeatable baseline is when the shell plate contacts the die. There is no law that says you have to, but it is a way to investigate a baseline for the sizing process that eliminates the largest possible contributor to variations.

For practical discussion, when the shell plate hits the die, there is no variation in the position of the process. That places the forced strain to what we would call a zero variation or less than what you could measure between the tools.

It isn’t impossible to set up a process that has a gap between the shell holder and die yet yields sizing that stays within control, but that requires the stiffness of the press linkages to be very high so that the scatter in the friction and cold working doesn’t end up creating scatter in the results.

Clearly there have been lots of very accomplished shooters who don’t make hard contact between the shell plate and die in their sizing process.

You should look for issues like the ones that have been mentioned above where something like a decapping stem prevents the die from controlling the process Or if the brass hasn’t finished fully flowing to the chamber and die.

If you want to try a good baseline to see the potential of your brass, lube, and dies, then I suggest you close down on the incremental shell holders and see what results, then decide on how to go forward. I have used both methods, but the easy button is hard contact to the shell holder if you want to see the repeatability potential of your tools and brass.

Leaving a gap requires higher technique and discipline compared to a positive mechanical stop for the ram or the shell holder. YMMV

Merry Christmas and Happy New Year!
Go JWST!
Click to expand...

Thanks - with the 0.008” shellholder, on average I’m achieving a 0.003” bump. I need 0.002” to feel nil resistance on bolt closure (as measured using my stripped bolt and rifle) which is important to me given the use case of this rifle (PRS comp - can’t break position to close a bolt forcefully).

I decap in a separate process. 3 firings on the brass now. Given the consistency in the headspace measurement Im quite confident they’ve hit full flow.

As for the die still not touching, I’ll try again to see if it’s a flex issue (which I’m doubting). Is there any chance it’s a concentricity issue with the centre of the die and centre of the shellholder not being aligned? I can see that leading to a gap as no amount of force would be able to force the remainder of the base of the brass body into two places at once.

Best way to check for this?

And Merry Christmas to all!
 
fatelvis said:
No matter how you are sizing, or what dies or press you are using, count three seconds when your brass is fully inside the die sizing it. Some called that dwell time. It helps minimize the variations.
Click to expand...
Three seconds is good but I use 7 sec dwell and I never have this issue. But my press is a cam over design and I think the zero is a hard stop correct?
 
I bump my sholders .003 and I like .003 clearence in my necks. I use an old Harrels varibase die and screw the bottom bushing out enough for a bump with just a little cam over and I use a little blue locktite to keep the bushing from turning. A small base Redding type S, is just right for my Hall "B" rail. I use the redding shell holders for the same effect. After several reloadings the sholder bump is down to .001 or less. By then its time for new brass. Not saying this is best, just saying what works for me. I get consistent results with smooth chambering rounds and have no hassle at the bench
 
Correct me if I’m wrong but following the wheeler stripped bolt method I believe it is recommended to bump .002 from the point of no resistance bolt drop.
 
scyzer said:
I do feel the cam over - but for some reason it just won’t get rid of the gap. I will double check for flex in the setup given I have it mounted using a inline fab quick change plate. Perhaps I didn’t torque the bolts down hard enough
Click to expand...

scyzer said:
.......I’ve tried to use the Redding Competition Shellholders and die contact in lieu of the other approach where you dial in bump based on rotating the die in and out and leaving a certain gap to achieve the right bump.
Click to expand...
However, with your new press you have not reached firm contact between the shellholder and the die while sizing, and there is still a gap.

Have you measured the gap with a feeler gauge? Is it consistent case to case?

scyzer said:
.........As for the die still not touching, I’ll try again to see if it’s a flex issue (which I’m doubting).......
Click to expand...
Echoing what others have said. I think you need to keep turning the die in, until the gap is gone, when the press cams over.

Another possibility is to turn the die in at least one more turn so that firm contact is reached before the press cams over.
 
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