Bumped Shoulders too much

[J E Custom]

Cam-Over has different meanings. One is built in with eccentric linkage design, the other is method.

Designed cam-over varies with different press designs. You can see it with movement of the ram through handle travel. The free ram raises, slows, stops, and finally lowers a bit.
Analogy in this is a lifter riding a cam lobe, going just past 0-Mark. The ram is a push rod.
My presses do this, I've yet to need interference contacts to bump shoulders 1thou after spring back(for bolt guns), but there are plenty of different situations out there.
For one, I don't use FL sizing dies for anything. And I would not vary my neck sizing lengths to adjust shoulder bumps anyway.. I use body dies for bumping, and neck dies for neck sizing.

Then you have presses(some very powerful) with no built in cam-over. With enough leverage you can flex them enough to reach full handle travel, with great interference, like caused with die contacting shell holder. This does not actually provide any more leverage or difference to the sizing function. That extra effort is merely stressing the press.
If the reasoning for this is a sloppy press, I suggest a local dumpster could rid you of that problem, and don't ever stress your next press. If the die isn't right, and maybe the manufacturer recommends interference contact, don't. Work around it or fix it with a better plan.

The worst plan I've seen is the common -raise the ram, screw the die down to contact the shell holder, + 1/8 turn for cam-over, with no followup verification of results.
Probability of correct bumping here is nearly nothing..

+1
I have a little different concept of caming over. I consider it as touching the shell holder with the dies and loading the press beyond the force needed to size the brass. caming over is old school and was recommended when dies were made to tolerances that required this process. and separate dies were needed for any sizing smaller than SAMMI dimensions (These dies were called "Small base dies" and were normally used for Simi-autos for ease of chambering.

Quality dies have a much broader range of adjustments today so caming over is not necessary to full size your brass. In fact, most high end dies have the full range of adjustments in order to get the sizing you need.

With the old dies that require cam over settings in order to get full sizing, a shim between the case head and the shell holder will give you what you want without grinding some of the shell holder top off or caming over.

J E CUSTOM

 

[bigedp51]

I would like to think Redding dies are quality dies and they also make the competition shell holders. And the instructions for the dies and shell holders are the same, run the die down until it touches the shell holder and then rotate the die a further 1/8 to 1/4 of a turn.

If the die does does not make hard contact with the shell holder, the sizing force, meaning amount of lube, diameter of the case, hardness of the brass can cause variations in shoulder location after full length sizing.

This is the very reason Redding made the competition shell holders, instead of putting shims under the lock ring of the die and creating air space between the die and shell holder.

On top of this anyone who neck sizes their brass puts far less force on the press. The proof in this is full length resize a case "without" the extra 1/8 to 1/4 of a turn and look at the gap between the die and shell holder at the top of the ram stroke. This air gap is the slop in the press and even the die moving upward in its threads.

If you want to carry this further then buy some once fired Lake City 7.62 cases fired in a machine gun and watch what happens with the added force on the press when sizing.

So again when the die makes hard contact with the shell holder any flex or slop in the press is eliminated. And the press is eliminated from any variations in case headspace length or shoulder location. (other than brass spring back)

Bottom line I would like to think the reloading die and equipment manufactures know what they are doing and telling us in their instructions. And the people reading this can separate personal opinions from the instructions with your dies.

 

[Bullet bumper]

The worst plan I've seen is the common -raise the ram, screw the die down to contact the shell holder, + 1/8 turn for cam-over, with no followup verification of results.
Probability of correct bumping here is nearly nothing..

I will drink to that 1/8 turn on a 7/8x14 thread moves the die approx .009 .
Way too much at a time.

 

[bigedp51]

With my Hornady cartridge case headspace gauge I simply measure a fired case and then select the correct Redding competition shell holder for the correct amount of shoulder bump.

The photo above is a fired case from my AR15 carbine and the plus +.004 Redding shell holder gives me .003 shoulder bump.

Not knocking anyone but we have too many neck sizers commenting on full length sizing, press flexing and shoulder bump.

I buy bulk once fired Lake City 5.56 and 7.62 cases and the sizing force on these cases is far more than the sizing effort of new cases fired in your chamber.

 

[Mikecr]

If the die does does not make hard contact with the shell holder, the sizing force, meaning amount of lube, diameter of the case, hardness of the brass can cause variations in shoulder location after full length sizing.

I understand what you're saying. That you're applying so much energy to your case sizing that your press flexes anyway, so you take that to a more stable point. A diminished return equals diminished affects.
I don't do that. I only bump shoulders, with that one action at a time.
There are many issues FL sizing brings to bear, that I won't ever put up with. It doesn't mean I don't understand the issues, just that I won't put myself in such a position.

Lube & brass hardness affects bump results just the same, and I feel strongly that we should verify correct bump with every case.

 

[bigedp51]

I was sizing 9mm pistol cases last night with a carbide sizing die. The die was screwed down until it touched the shell holder and then backed off a smidgen.

With the naked eye I could see the air gap increase between the die and shell holder. And I could also see the die ever so slightly move, and this was just the case pushing upward on the "dry" carbide die.

I can't tell you how many times I have read in forums of people using a progressive press getting varying case headspace lengths when full length sizing. And this is due to the press design and slop in the sizing operation.

And Glen Zediker in his latest book tells you the die shouldn't touch the shell holder because it strains the press. All I can say is my 44 year old Rockchucker press likes hard contact with the shell holder with press cam over for uniform shoulder location.

Maybe some of you have new presses made of super cast iron that never flexes when push comes to shove.

And if the OP had a Hornady cartridge case headspace gauge we wouldn't be reading his posting here.


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[D.Camilleri]

I was sizing 9mm pistol cases last night with a carbide sizing die. The die was screwed down until it touched the shell holder and then backed off a smidgen.

With the naked eye I could see the air gap increase between the die and shell holder. And I could also see the die ever so slightly move, and this was just the case pushing upward on the "dry" carbide die.

I can't tell you how many times I have read in forums of people using a progressive press getting varying case headspace lengths when full length sizing. And this is due to the press design and slop in the sizing operation.

And Glen Zediker in his latest book tells you the die shouldn't touch the shell holder because it strains the press. All I can say is my 44 year old Rockchucker press likes hard contact with the shell holder with press cam over for uniform shoulder location.

Maybe some of you have new presses made of super cast iron that never flexes when push comes to shove.

And if the OP had a Hornady cartridge case headspace gauge we wouldn't be reading his posting here.


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I do have a Hornady cartridge case headspace gauge and it showed me that new remington brass and new Bertram brass are the correct dimension and new Nosler brass for a 338 RUM is .010 short. I went through and made sure my brass was being sized proper last fall, loaded ammo, killed deer and elk and then went through winter, broke my ankle, had surgery, then a pulmonary embolism that almost killed me and then went to the loading bench. I grabbed the wrong set of full length sizing dies and didn't realize it was sizing under sized. The reason I caught the mistake was because of my Hornady cartridge case headspace gauge. Now the real question is should I load some of this short brass up and test it? Bear in mind that it is the same dimension as new Nosler brass I have.

 

[Rich Coyle]

Now the real question is should I load some of this short brass up and test it? Bear in mind that it is the same dimension as new Nosler brass I have.

Of course you should go shoot it.

 

[Gene]

Just occurred to me. PMA makes a lock ring with hash marks for this purpose. When installed run it down until it allows the shoulder to barely touch the die. Go down a hash mark or .001" until it barely moves the shoulder and try the case fit until it is just snug.


PMA Micro Die Adjuster w/ Thumb Screw Upgrade - PMA Tool

 

[Rich Coyle]

Last night I look at the space between the full length die and the shell holder when fully sizing a case. There was about .040". But then this is a wildcat so I guess it can't be considered.

 

[Edd]

Last night I look at the space between the full length die and the shell holder when fully sizing a case. There was about .040". But then this is a wildcat so I guess it can't be considered.

It can and should be considered for sizing your cases. Determine exactly how big the gap is when the case is correctly sized and buy a round shim of that thickness. Then use that shim between the shell holder and the die when sizing your cases. That makes setup easy and your cases will always be the correct length.

 

[Rich Coyle]

It can and should be considered for sizing your cases. Determine exactly how big the gap is when the case is correctly sized and buy a round shim of that thickness. Then use that shim between the shell holder and the die when sizing your cases. That makes setup easy and your cases will always be the correct length.

I tried that with two 6.5RUMLNs. Their headspaces differed by .006". I made a shim of .006" and figured I had a wonderful idea. It didn't work. I will continue to check every case when they are sized.

 

[bigedp51]

Pausing at the top of the ram stroke for a few seconds greatly reduces brass spring back.

 

[Mikecr]

Using a body die for bumping, I creep in close to intended with a small amount of RCBS case lube. Then I add a smidge more lube to the shoulder & size for better. It's just another thin wipe with my fingers. After a bit, I get pretty good at it, and I'm watching as I always measure each.

All cases hold there own character, and some will spring back more, taking more lube to hit target. Some will spring back less.. Where I over bump slightly on this, I use them anyway & clean the die where a trend is apparent. But if it seems many it's time to anneal the batch.
I bump 1thou (+/-) 1/2thou. With that I can well chamber for ~2months. If I need to store ammo longer, I'll bump 2thou (-)1/2thou. My primer crush settings are similar and likewise.