CAM OVER

[Uncle Ed]

If you measure a fired case (spent primer removed) using a bump gauge and a caliper then adjust the die to set the shoulder back .001 to .002" (bolt rifles) doesn't that determine the degree of cam over / under required?

At least it's been my experience that adjusting a full length sizing die (up or down) does change the amount of shoulder set back. Also, in some cartridges if the shoulder is not touched the die can extrude the case actually making it longer. I've noticed this especially with the 243 Win and 308 Win.

I also found that the amount of cam over / under can vary with the brand of brass, the rifle, and the age (number of times resized) of the case. In the latter case I check three cases in the lot as the cases age to see if some adjustment is needed.

I use Skip's Shims (available at Sinclair) to make adjustments to the amount of cam over / under. Seems to work fairly consistent and they're not expensive.

German Salazar wrote a very comprehensive and informative article on case full length resizing but I think his blog is no longer active. It might be useful if it could be posted here if he could be contacted and permit the article to be posted on this site.

Mr. Salizars web pages are still alive and well at web.archive.org.

The Rifleman's Journal Index of Articles
https://web.archive.org/web/2015031...ansjournal.blogspot.com/p/articles-index.html

 

[Uncle Ed]

Before the Redding competition shell holder were made by them you adjusted the die for bump with feeler gauges.

The problem with this method is the air gap between the die and shell holder and not eliminating any flex in the press. And Skips shims raise the die above the shell holder and add to any press flex problems.

And Redding, RCBS and Forster dies instructions tell you to turn the die 1/8 to 1/4 past contact with the shell holder.

And we have talked about pausing at the top of the ram stroke to get more uniform shoulder bump. And if the press has any flex you need to have the die make hard contact with the shell holder.

 

[bozo699]

Mr. Salizars web pages are still alive and well at web.archive.org.

The Rifleman's Journal Index of Articles
https://web.archive.org/web/2015031...ansjournal.blogspot.com/p/articles-index.html

There ain’t nothing there Ed.
Wayne

 

[Uncle Ed]

There ain’t nothing there Ed.
Wayne

Wayne I can access all the links on the main page I posted for "The Rifleman's Journal". If you lube you keyboard keys like you lube your cases you might be sliding past the webpage.

NOTE, when I click on the link below I go to that webpage, you might need to adjust your web browser you are using. I copied the image and some of what was printed below it to show what is there.


Basics: Resizing - Case Dimension Changes
Resizing - Case Dimension Changes
by: Germán A. Salazar
https://web.archive.org/web/2015031...6/basics-resizing-case-dimension-changes.html

When you get home from the range with a box full of fired brass, it's time to get to work. The most fundamental decision to be made is how to resize the brass - will it be full length sized or neck sized? Some people believe there is a third alternative: partial full length sizing. Once you've performed the procedures shown in this article, I think you'll understand and agree that neck-sizing is not suitable for Highpower shooting, that full-length sizing is the best way to resize cases and that the third option is no option at all. I also hope you will have a better understanding of what goes on inside the resizing die.



Some of the noticeable effects of improper resizing are:

• hard bolt closing,
• hard bolt opening after firing rounds that have normal pressure,
• a click at the top of the bolt opening stroke with normal pressure loads,
• early case head separation,
• damage to the bolt locking lugs,
• frustration leading to assorted venial sins.

 

[dgeesaman]

I think I follow you. Is tight body to chamber fit overrated? Why not drastically resize cases, back to minimum? After all, what could be more drastically undersized than the 6 BR you started with, and shot so well?

Minimum sizing is to avoid overworking the brass. We can anneal necks that have to expand and contract repeatedly but the body of the case cannot. If you let the body of the case move significantly for multiple cycles you will create other problems.

If someone decides their gun shoots best as a fireforming round only and doesn’t reload the brass just let me send a box with postage paid to get rid of your spent brass.

 

[KMart]

There ain’t nothing there Ed.
Wayne

It came up for me. It may just take some time. Kind of like a Way Back machine.

 

[J.d. Popkes]

I think when it comes to sizing, consistency is most important. Bump 1,2,3 thou, whatever, as long as they are identical. Which is why it’s not surprising to get accuracy from a fire form load or virgin brass.

I know for certain, on paper, and on a chronograph that inconsistent bump/sizing matters. I can put on a clinic with crap that don’t work that I learned the hard way. I can’t tell you what to do but I am full of examples of what not to do. Just think how much time, money, and energy I could have saved, but it’s ever evolving learning all the time.

#cam-over-for-life

 

[Dusty Stevens]

I guess its all in the press design and the depth your die is reamed. Im not going to screw a die down hard on a shellholder if that causes me to bump my shoulders .025, but when the case bottoms out in the die it does bump and cam over just as if i had it set according to instructions

 

[J.d. Popkes]

I guess its all in the press design and the depth your die is reamed. Im not going to screw a die down hard on a shellholder if that causes me to bump my shoulders .025, but when the case bottoms out in the die it does bump and cam over just as if i had it set according to instructions

Some die makers make them like that where you would need a +25 shell holder. This was part of my learning process. Now I know who makes dies within my range and are designed for camming. And who purposely designed them .025 short for the other way.

 

[bozo699]

Wayne I can access all the links on the main page I posted for "The Rifleman's Journal". If you lube you keyboard keys like you lube your cases you might be sliding past the webpage.

NOTE, when I click on the link below I go to that webpage, you might need to adjust your web browser you are using. I copied the image and some of what was printed below it to show what is there.


Basics: Resizing - Case Dimension Changes
Resizing - Case Dimension Changes
by: Germán A. Salazar
https://web.archive.org/web/2015031...6/basics-resizing-case-dimension-changes.html

When you get home from the range with a box full of fired brass, it's time to get to work. The most fundamental decision to be made is how to resize the brass - will it be full length sized or neck sized? Some people believe there is a third alternative: partial full length sizing. Once you've performed the procedures shown in this article, I think you'll understand and agree that neck-sizing is not suitable for Highpower shooting, that full-length sizing is the best way to resize cases and that the third option is no option at all. I also hope you will have a better understanding of what goes on inside the resizing die.



Some of the noticeable effects of improper resizing are:

• hard bolt closing,
• hard bolt opening after firing rounds that have normal pressure,
• a click at the top of the bolt opening stroke with normal pressure loads,
• early case head separation,
• damage to the bolt locking lugs,
• frustration leading to assorted venial sins.

hi Ed,
I just get this and it won’t go further. I’m in a iPhone maybe I need a full blown computer idk but thanks for the post so I can read it anyway.
Wayne

 

[Pawnee Bill]

I spoke with the president of Redding about their T-7 press, and if it was ok to use cam-over when loading. He said they DESIGNED it to be used camming over consistently, and that removes slop from the linkage, turret head, and die threads. He said by all means, continue camming over, and don't worry about destroying your press, they have presses in their shop that have had a multitude (can't remember the large number) of rounds loaded through them without fail.

Exactly! Camming just takes out the slop all around.

 

[B23]

Sometimes I think many view this whole cam over thing like we're using excessive force. It's not like we're caming over with a 4ft cheater bar on the end of the handle.

 

[243winxb]

Simply measure the difference. Touching vs cam over, using RCBS equipment.

NOTE: The firing pin strike may set that perfect shoulder bump back .006" on firing . (Savage Axis 223)

 

[Uncle Ed]

I guess its all in the press design and the depth your die is reamed. Im not going to screw a die down hard on a shellholder if that causes me to bump my shoulders .025, but when the case bottoms out in the die it does bump and cam over just as if i had it set according to instructions

In the past you adjusted the die with feeler gauges adjusting the "air gap" between the die and shell holder.

With the Redding competition shell holders you do not touch the die to adjust the amount of shoulder bump. All you do is start at the +.010 shell holder and work down in size until you get the proper amount of shoulder bump.


Competition Shellholder Sets
Makes every die a custom die!

Now you can control headspace. The new Redding Competition Shellholders are packaged in five piece sets in .002” increments (+.002”, +.004”. +.006”, +.008” and +.010”). Each shellholder has a distinct black oxide finish and is clearly marked to indicate the amount it will decrease case-to-chamber headspace. You can now easily adjust the shoulder bump to customize cases to your specific chamber.

 

[Dusty Stevens]

Competition Shellholder Sets
Makes every die a custom die!

Now you can control headspace. The new Redding Competition Shellholders are packaged in five piece sets in .002” increments (+.002”, +.004”. +.006”, +.008” and +.010”). Each shellholder has a distinct black oxide finish and is clearly marked to indicate the amount it will decrease case-to-chamber headspace. You can now easily adjust the shoulder bump to customize cases to your specific chamber.

I have never needed those in all my years. Never seen anybody use a set either.

 

[bozo699]

I have never needed those in all my years. Never seen anybody use a set either.

Me either ,... never seen the need.
Wayne

 

[David Christian]

I’ve used the competition shell holders with great success. I would call them a convenience to precision die set up, not an absolute necessity. They saved me a bit of time in setting the lock ring once and not having to fidget back and forth for the perfect bump.

I could see them being more beneficial to someone who was reloading for multiple rifles chambered with slightly different head spacing. Set the lock ring once and then just fine tune with different sized shell holders.

 

[Uncle Ed]

Years ago, I set a FL die so that it touched the shell holder with the ram at the top of its stroke. The press was a Rock Chucker. Then I sized a case, and with the case in the die, at the top of the stroke, there was a gap, that I measured with a feeler gauge. It was .006. Evidently the sizing load had stretched the linkage a bit. This is just another example of something being a bit more complex that it might seem to be at first glance.

Boyd saw the air gap above and said sizing being a bit more complex that it might seem to be at first glance.

The Redding competition shell holders allows you to make hard contact between the die and shell holder with no air gap. This takes the slop out of the press linkage, compensates for different brands of cases and their hardness. And makes the case shoulders more uniform after sizing.

If you use the same brand of brass and anneal every time then maybe your press and sizing method do not require competition shell holders.

P.S. bozo699 for agreeing with Dusty may the fleas of a thousand camels infest your crotch.

 

[bozo699]

Boyd saw the air gap above and said sizing being a bit more complex that it might seem to be at first glance.

The Redding competition shell holders allows you to make hard contact between the die and shell holder with no air gap. This takes the slop out of the press linkage, compensates for different brands of cases and their hardness. And makes the case shoulders more uniform after sizing.

If you use the same brand of brass and anneal every time then maybe your press and sizing method do not require competition shell holders.

P.S. bozo699 for agreeing with Dusty may the fleas of a thousand camels infest your crotch.

Ed,
I may have to agree with Dusty more often lol
Happy Bumping buddy

 

[ronsatspokane]

I think he’s trying to say that fireforming uses brass with huge clearances, as if the brass was grossly over-sized in a die. Yet fireformers can shoot very well at times.

My answer to that is: fireforming 6BRA involves brass that is still very well aligned by the fit at the neck/shoulder junction and/or the bullet jammed in the throat. So yes it’s not surprising it can shoot. Velocity might not be reliable but in short range there are plenty of shooters who shoot fireformers in fun matches.

David

Yes, that is what I'm saying. As far as velocity, I had the Labradar running and the SD and ES numbers were pretty darn good. SD in the single digits.