Sizing issues

[1shot]

I recently started loading a cartridge that is new to me. (6 ARC) I purchased a FL RCBS SB sizer die and set it up in my co-ax press. Everything was fine until one of the shell plates gave up the ghost. NP says I, so I grabbed a #12 shell holder and moved everything over to my Redding T7 press. Now even though the shell holder hard bottoms out on the die, I'm still .0015 short of bumping the shoulder at all. In over 50 years of reloading I have never experienced this. I currently have a Redding 6 shell holder competition set of shell holders ordered in hopes that this will fix the problem, so we will see. Any thoughts on this issue would be appreciated.
Thanks,

Lloyd

 

[ruthless11]

I recently started loading a cartridge that is new to me. (6 ARC) I purchased a FL RCBS SB sizer die and set it up in my co-ax press. Everything was fine until one of the shell plates gave up the ghost. NP says I, so I grabbed a #12 shell holder and moved everything over to my Redding T7 press. Now even though the shell holder hard bottoms out on the die, I'm still .0015 short of bumping the shoulder at all. In over 50 years of reloading I have never experienced this. I currently have a Redding 6 shell holder competition set of shell holders ordered in hopes that this will fix the problem, so we will see. Any thoughts on this issue would be appreciated.
Thanks,

Lloyd

grind about .005 off the shell holder ,redding wont fix problem they are longer not shorter.

 

[kenhwind]

Do you have your die set to cam over?

Are you using an RCBS shell holder with your RCBS die? I have found that it makes a difference to use dies and shell holder of the same brand.

It seems to me that if the dies are in spec, the press works, then it is just something simple.

But I could be wrong.

I'd use a regular sizing die and then the SB die. I only used my small base dies when necessary.

 

[Webster]

I recently started loading a cartridge that is new to me. (6 ARC) I purchased a FL RCBS SB sizer die and set it up in my co-ax press. Everything was fine until one of the shell plates gave up the ghost. NP says I, so I grabbed a #12 shell holder and moved everything over to my Redding T7 press. Now even though the shell holder hard bottoms out on the die, I'm still .0015 short of bumping the shoulder at all. In over 50 years of reloading I have never experienced this. I currently have a Redding 6 shell holder competition set of shell holders ordered in hopes that this will fix the problem, so we will see. Any thoughts on this issue would be appreciated.
Thanks,

Lloyd

If the case chambers easily after shooting it still has not moved forward enough to fit the chamber. It doesn't need to be bumped. Sometimes you have to fire a case several times to get a good fit to the chamber dimensions. Never had this kind of problem. Like someone else said shell holder and die may need to be the same brand. I reloaded for about 40 years before I measured shoulder bump when adjusting dies.

Before maybe year 2000 no-one even knew what shoulder bump was.

 

[K22]

Why are you using a SB die?

Do you need to bump the shoulder?
In other words, if the cases have not fire formed to the rifle chamber there may be no need to bump the shoulder at this point?
Here's the procedure I use when encountering a similar issue, often with virgin cases.
- Check fired case head space with bump gauge then check in rifle chamber. If the case chambers without issue, then set the F/L die for zero bump then check in rifle chamber. Make sure case head space after sizing does not exceed the fired case head space, i.e., no extrusion.
- If the zero bump chambers without issue, use the fired case die setting as your baseline.

I too have over 50+ years of experience reloading, and I never had to alter an RCBS shell holder when used with an RCBS F/L die. However, I have no experience with a Co-AX press. With conventional presses, many require some level of cam over to bump the shoulder due to the play in the linkages.

 

[DaveTooley]

Insert a case into the FL but do not reverse the stroke. Look for a gap between the shell holder and the die. That shows you how much spring you have in your press. Creep down with the die until you either get the number you want or the shell holder contacts the die under a load.

 

[ShtrRdy]

I had something like this happen a long time ago with RCBS tools and I ended up removing a few thousands of an inch off the top of the shell holder. I used sand paper for the removal.

 

[LCazador]

For what it's worth I've been bumping shoulders since early 70's when my smith made a barrel stub for me for measuring bump. I think you have a die set up problem or it could be that an RCBS branded shell holder is all that is needed. Redding competition shell holders will take you in the opposite direction giving you less bump in increments of .002". Your Redding T7 could have enough spring in the head to create this problem as well. How are you measuring bump? What Dave Tooley says above

 

[kenhwind]

I only use a SB die on brass that doesn't fit into the cartridge gauge.

 

[WillFS]

I have a Wilson 6BRA die that would not bump the shoulder without excessive cam over in my Redding press. A friend took some material off the top of the shell holder for me and now it all works fine.

 

[JMayo]

He said shell holder was bottoming out on the die.
Shim under the case might raise it enough. I've used paper, plastic or feeler gage before. I got my GS to shorten a die.
A competition holder is shorter than regular ones i believe.

 

[PhilC]

I modified a shellholder like others mentioned - problem solved.

 

[1shot]

Thanks for the replies so far. I will try and answer everyone's questions.
The shell holder I am using on the T7 is a Redding, only the die is RCBS.
All of the following measurements are taken with a digital Mititoyo dial caliper and bump gauge.
* All of these measurements are done with a bump gauge.
The shoulder measures 1.188" from base to datum on unfired brass.
The same dimension on a piece of fired brass is 1.194"
In order to get the bolt with the firing pin assembly removed to close with the weight of my finger on the bolt handle require that I bump the shoulder to 1.1855".
As I said in my original post, everything worked fine in the co-ox as the shell plate is much thinner. In order to get the shoulder bump that I need, the die is bottoming out on the shell holder of the co-ax.
With the taller Redding shell holder in the T7 even though it is bottoming out hard on the die, it won't bump shorter than 1.189".

The reason I have a small base die is I originally built an Ar-15 rifle for this cartridge and loved it so much, I had a bolt rifle chambered in it.
If I missed addressing any of your suggestions, please advise.
Thanks,

Lloyd

 

[M-61]

That shows you how much spring you have in your press.

You lost me here.
I don’t want to discuss shoulder bumping.
Just what press spring you’re referring to.

 

[M-61]

That’s about right

 

[dthomas]

Somethings not right with your measurements. New brass chambers but is over .003 longer than the brass that is sized and won't chamber.

 

[64Rambler]

Keith has a good discussion about sizing brass that hasn't quite fully formed to the chamber yet.

 

[DaveTooley]

You lost me here.
I don’t want to discuss shoulder bumping.
Just what press spring you’re referring to.

I don't want to discuss shoulder bump either. It's on my list right under seating primers.
Every press has some change in it under a load. It could be the frame and/or the linkage. Just screwing the die down until it touches the shell holder does not get the full travel of the ram because of the spring in the system. Many who have to overcome this call it cam over when setting up the FL die. It's just a different description of what I'm saying.

 

[moondog]

I've had a similar issue with some Caliber I don't remember anymore. Redding shell holders are thicker than just about everyone else. Grind it, or compare it to RCBS or Lee

 

[SeabeeKen]

How much deflection is there in that t7 turret head?