Redding Competiton Shellholders in a Forster Co-Ax Press?

[PatMiles]

I understand the advantages of using the Redding Competition Shellholders in a ram type press where the shellholder and the die interaction can be adjusted for repeatable headspace bump due to the camover of the press. As a Co-Ax press does not allow for camover can the same consistant shoulder setback be attained?
A curious mind wants to know.

Here's hoping that all the good folks on the Accurate Shooter Forums have a blessed, Merry Christmas and a happy and prosperous new year!

 

[Mark M.]

I understand the advantages of using the Redding Competition Shellholders in a ram type press where the shellholder and the die interaction can be adjusted for repeatable headspace bump due to the camover of the press. As a Co-Ax press does not allow for camover can the same consistant shoulder setback be attained?
A curious mind wants to know.

Here's hoping that all the good folks on the Accurate Shooter Forums have a blessed, Merry Christmas and a happy and prosperous new year!

Forster offers an adapter for the coax press that allows the use of the traditional shell holder

 

[PatMiles]

Forster offers an adapter for the coax press that allows the use of the traditional shell holder

I have that.
I’m wanting to know opinions if the same repeatable, accurate headspace setback can be attained with the Co-Ax press that does not have a camover capability.

 

[6BRA]

Yes. I would never run a shellholder on a coax. Defeats the purpose of the floating press components. Occasionally .0005 off but rarely. I anneal every firing. AMP.

 

[TTE]

Yes. I would never run a shellholder on a coax. Defeats the purpose of the floating press components. Occasionally .0005 off but rarely. I anneal every firing. AMP.

I agree with this ^^^

However to answer your question, the way I see it you can only pull the handle down so far until it stops. I would imagine that point would be the same with each handle pull. But have not tried it on my Co Ax

 

[PatMiles]

Yes. I would never run a shellholder on a coax. Defeats the purpose of the floating press components. Occasionally .0005 off but rarely. I anneal every firing. AMP.

I bypass this problem by not securing the shellholder by tightening the horizontal setscrew in the adaptor. This allows the shellholder to float in the adaptor.

 

[furrybean]

I’ve made some wear plates with different thicknesses to give varying headspace with hard cam over
Before this I was getting excessive variation in headspace

 

[PatMiles]

I’ve made some wear plates with different thicknesses to give varying headspace with hard cam over
Before this I was getting excessive variation in headspace

How are you getting cam over on your Co-Ax?

 

[DiffEQ]

I have that.
I’m wanting to know opinions if the same repeatable, accurate headspace setback can be attained with the Co-Ax press that does not have a camover capability.

Absolutely.
It makes no sense to me to use a shell holder in a Co-Ax.
You do realize, clamming over does not change the maximum stroke length of the ram?

 

[PatMiles]

Absolutely.
It makes no sense to me to use a shell holder in a Co-Ax.
You do realize, clamming over does not change the maximum stroke length of the ram?

I realize that, but a shell holder provides a positive stop for the "rams" where the spring loaded shell holder does not.

 

[6BRA]

What dies are you running? I've never had to bring the die in contact with plate.The case head is on bottom below the plate.the plate jaws merely loose grip the rim to allow for float. The plate isn't supporting the case head.

 

[PatMiles]

Using a Whidden sizing die with neck bushing.
In trying to get accurate, repeatable shoulder set back the cam over method where the shell holder and the bottom of the die contact each other (thus providing a repeatable POSITIVE stop) has proven to be the most accurate and repeatable method.

 

[PatMiles]

I'll probably have to break out my RCBS press so I can adjust my resizing dies for cam over.

 

[6BRA]

I would have excessive headsoace if I did that. I can maintain .0005 the way the coax sits. Good luck. Even annealed brass on a per case basis may yield .0005. Stubborn cases.
How much variance are you getting, case to case?

 

[PatMiles]

Up to .002". Cases are AMP annealed after every firing. Just going down this rabbit hole to see what amount of effort is required to see if my shoulder set back can be dead nuts on every time.
Fortunately I have an old RCBS press I can experiment with.

 

[DiffEQ]

I realize that, but a shell holder provides a positive stop for the "rams" where the spring loaded shell holder does not.

Do you understand how a Co-Ax works?
If you're using the shell holder against the die as the limit of travel, cam-over is irrelevant, and your variance depends on how accurate the thread mating is between the die and press.
Edit to add, I don't think you understand the mechanics of a Co-Ax. The spring loaded jaws only provide a relative reference for die placement. Then you adjust for your needs. I don't think a single die of mine touches the jaws. The base of the ram (below the jaws) is the datum surface.

 

[243winxb]

the cam over method where the shell holder and the bottom of the die contact each other. Proven to be the most accurate and repeatable method.

​

RCBS has said, contact is needed to align/square the fl die with the shell holder.
Lock die in the RCBS press while in cam over.

If less bump is wanted- use Redding Competition Shellholders.

Light vs heavy cam over will make a difference in the amount of shoulder bump.

 

[Richard Jones]

Pat,
I use shellholders in my CoAx. I do not use the competition shellholders, but repeatable results are easily doable, so I would think they would work fine.

"I would never run a shellholder on a coax. Defeats the purpose of the floating press components." I disagree with that statement.

Shellholders float just fine. Why would you think otherwise? What is preventing a shellholder from floating vs whatever float you get out of the jaws? To me, the jaws would provide less float than a shellholder, although I have not tested it. I do remember the jaws grabbing the case pretty hard and I have not missed those things at all. That's just me, you do you. Simply use the same shellholder that you initially set your dies with.

 

[PatMiles]

Pat,
I use shellholders in my CoAx. I do not use the competition shellholders, but repeatable results are easily doable, so I would think they would work fine.

"I would never run a shellholder on a coax. Defeats the purpose of the floating press components." I disagree with that statement.

Shellholders float just fine. Why would you think otherwise? What is preventing a shellholder from floating vs whatever float you get out of the jaws? To me, the jaws would provide less float than a shellholder, although I have not tested it. I do remember the jaws grabbing the case pretty hard and I have not missed those things at all. That's just me, you do you. Simply use the same shellholder that you initially set your dies with.

Agree, just trying something different to attain better results.

 

[neckturner]

As a Co-Ax press does not allow for camover can the same consistant shoulder setback be attained?

I used the Comp shell holders for years in a Co-Ax. They worked fine with repeatable shoulder set back.