How much case length growth measured base to shoulder should one expect with first firing?

[barefoot1]

Redding could have re-worded their ad. The video tells the story well.

Much better than grinding down shell holders. Running precision grinding equipment in my early aerospace days tells me doing it by hand is making other problems appear. Unless we all had surface grinders.....

OK just to clarify. I am not disputing the use of the Redding Shell holders at all. That whole part of my post about grinding down shell holders came from Post#4 Sedancowboy. I can't even think of a scenario where I would do that! Once again I have watched the video, completely understand their usage, and have three sets of them along with caliber specific dies that I use regularly to "bump" back shoulders closer to the base by increasing the thickness of the shellholder incrementally. Whew!

 

[Bob Wright]

OK just to clarify. I am not disputing the use of the Redding Shell holders at all. That whole part of my post about grinding down shell holders came from Post#4 Sedancowboy. I can't even think of a scenario where I would do that! Once again I have watched the video, completely understand their usage, and have three sets of them along with caliber specific dies that I use regularly to "bump" back shoulders closer to the base by increasing the thickness of the shellholder incrementally. Whew!

Can you measure from the top of the shell holder to the "floor" of the shelholder (where the cartridge head rests on a #10, 8 and 6? Or anything you can.. since most guys are doing the same in the video, setting the die to shell holder for a light cam-over. The only + or - has to be measured from the top of the shell holder to the floor of the shell holder.
In other words +.010 moves the floor and cartridge up the least and a +.006 = .004 more vertical brass movement into the die for bump....
Is that what you see?
It's the only way that makes sense, never adjusting the die, but changing the shell holder with identical cam-over. Only the floor moves up.

 

[barefoot1]

Can you measure from the top of the shell holder to the "floor" of the shelholder (where the cartridge head rests on a #10, 8 and 6? Or anything you can.. since most guys are doing the same in the video, setting the die to shell holder for a light cam-over. The only + or - has to be measured from the top of the shell holder to the floor of the shell holder.
In other words +.010 moves the floor and cartridge up the least and a +.006 = .004 more vertical brass movement into the die for bump....
Is that what you see?
It's the only way that makes sense, never adjusting the die, but changing the shell holder with identical cam-over. Only the floor moves up.

Correct. I think the issue is that I am saying "increase" the thickness of the shell holder-should be "decrease or increase" depending o the amount of bump back you want. The thinner the thickness of the shell holder the more bump you get.

 

[Mikecr]

It's the only way that makes sense, never adjusting the die, but changing the shell holder with identical cam-over.

The cam-over would change if you did not adjust the die for shellholder change. That is, unless you have a really really sloppy press.

I don't like doing these adjustments any more than I have to, so I store a die as ring set and the shellholder that provides correct bump -together in a box -for each barrel.
In other words, I don't keep the competition shell holders intact as a set, as I do not keep neck bushings in a universal set. What works, stays with the barrel. A little more expense (potential), but ease of reloading is worth it to me.

 

[Mc Fraser]

My 300wm get 10-15 thou after each firing

 

[243winxb]

Saami- ISSUED: 06/18/2019 6.5-284 NORMA

Maximum rounds to minimum chamber .000"

Minimum Round to Maximum chamber .017" Head to datum.

So a fired round may not grow at all or it may stretch .017"

 

[SheepSeeker]

This is not rocket science. The video (and Redfield) could not be more clear. As the fellow says in the video the FLOOR of the shellholder changes. Thus when you move from .010 to the smaller numbers, the case goes into the die FARTHER and moves back the shoulder.
Perhaps owning a set and using them is the only way to understand.

 

[Bob Wright]

This is not rocket science. The video (and Redfield) could not be more clear. As the fellow says in the video the FLOOR of the shellholder changes. Thus when you move from .010 to the smaller numbers, the case goes into the die FARTHER and moves back the shoulder.
Perhaps owning a set and using them is the only way to understand.

There were enough comments saying these shellholders did not move the brass up into the die to get that shoulder bump. It was driving me nuts. I don't need them, but a simple measurement was enough evidence for those that were slightly confused.
Reddings description just adds the confusion. Basically, simple arithmetic.

 

[SheepSeeker]

The video was crystal clear. Anyone who owns them know what they are for.

Think about it --- what possible reason could there be to design a shell holder to make a case longer ? If you wanted that, just back the die out

 

[Tulsa Reiner]

watch the video from 2:09 - 2:15 . Broz says to start with the .010 shellholder it sizes the least . maybe you guys will believe him . I said the same thing in post #10 .

I have a problem accepting his technique of judging .002" headspace by the feel of the bolt closure. That might be ok for choosing the correct Redding Precision Shellholder, but to know consistency of my headspace, I want to actually measure the CBTO with something like the Hornady Headspace Comparator. I, in fact, measure the CBTO of my fired brass, then again after sizing, to know the amount of headspace bump I have performed.

 

[Mikecr]

Headspace is not CBTO (cartridge base to ogive).
It's no more than a local 'BUMP' of shoulders to achieve acceptable headspace.
Instead of holding faith in reamer prints or manuals you should establish zero headspace(via fire forming), measure it, log it, bump from there.

The measure part will be with a local tool of yours. A gizzy taking datum anywhere on the case shoulder.
Even with this, ultimately, you will need to feel the chambering to validate satisfactory results.
You feel zero HS (just when a stripped bolt will not freely turn against the chambering of a case), you bump ~1thou as measured with your gizzy, you confirm that the case now chambers with no resistance. Then you can bump another ~1/2thou to be sure the springback (which continues over time) will not leave you with difficult chambering down the road.
Well that's what I do. I creep into 1.5thou bumps with varying case lube, rotations and hold delays. And before using the ammo, if delayed by a month or more, I run every single round through the chamber to be sure.

 

[jimbires]

I have a problem accepting his technique of judging .002" headspace by the feel of the bolt closure. That might be ok for choosing the correct Redding Precision Shellholder, but to know consistency of my headspace, I want to actually measure the CBTO with something like the Hornady Headspace Comparator. I, in fact, measure the CBTO of my fired brass, then again after sizing, to know the amount of headspace bump I have performed.

I do as you said . I measure shoulder bump from fully expanded brass . the reason I pointed out the spot in the video , is the guys replying on this thread think the redding comp shellholder sets size the brass more . I've been trying to tell them these sets size the brass less , but I still don't think they have grasped that .

 

[SheepSeeker]

They don't size it more. They INCREASE the shoulder bump BACK. I don't know how you could watch that video and think they made the base to shoulder measurement LONGER. Perhaps you can explain how any die can STRETCH a case ?

Perhaps a call to Redding is in order ?

 

[sedancowboy]

I will make one more attempt to explain how the Redding Competition Shell holders work.
A standard shell holder is .125 from the case base to the top where it contacts the die with the ram fully extended. So there is .125 of the case that never goes into the die. This is generally too much sizing for long case life.
The Redding Competition Shell holders are sold in a set of 5 with the first one being marked +.002 which is .127 from the base to where it contacts the bottom of the die. So using the first Redding Shell holder you have sized the shoulder .002 less than the standard shell holder or to say it another way the case base to datum line measurement is now .002 longer than if you had used a standard shell holder of .125.
You may continue up the ladder by choosing a +.010 which is .010 taller than a standard shell holder which means now that .135 of the case cannot enter the die so the case base to datum line measurement is .010 longer than if you had used a standard shell holder. Each of the Redding shell holders are made to help you achieve a shoulder set back of your choosing. Between the standard shell holder of .125 which gives you the most sizing or the .135 shell holder which is marked +.010 and gives you the least sizing or the longest case base to Datum line.
These shell holders are a great tool to be able to bump shoulders back to suit your needs since a standard shell holder would oversize your brass. I do wish they would make a set with minis shell holders because sometimes you can have a tight chamber and need more sizing to get the desired result.
I notice some confusion about the numbers and if you start with the +.010 shell holder then move down you are decreasing the case base to datum line. But you are increasing the amount of sizing. At no time has anyone said that these shell holders increase the case base to datum line they reduce it but they reduce it by less than a standard shell holder of .125 height.
I hear the argument all the time that why not just back the die our to get the desired shoulder bump, because it is not as consistent as the shell holder hitting hard on the bottom of the die. When the shell holder hits the bottom of the die you have a very consistent stop. To move that stop you change shell holders hence the Redding Competition Shell holders. They are a great tool,. I do wish that people who do not have them would stop arguing about how they work.
Henry