No problem hawnddawg , happy to help . It’s important we all know what the TRUTH is . The great thing about the truth is you can’t be considered a troll or to be disrupting a thread as long as what you say is technically correct regardless of how irrelevant it is to the thread .
Don't stress your press
- Thread starter hounddawg
- Start date
Did an experiment with some old Hornady .260 Rem brass, my normal S bushing FL die and a Redding body die.
Using my lying calipers and a .400 comparitor in my Hornady case gage I did some measurements. Before sizing the distance from base to case mouth was 2.024 inches and the distance from base to shoulder datum was 1.627. I took one piece of the brass and sized it with my bushing die to 1.624.
Then I took a second piece of brass and replaced the bushing die with a body die since I do not want to mess with the adjustment on my normal die. I set the body die to where I was getting sized brass with the shoulder set back to 1.624 and took feeler gages and tried to slip them between the top of the caseholder. I came up with about .009 clearance. After I lowered the ram I turned the die down 1/2 turn and this time went camover. Clearance between the case holder was zero this time and a measurement of the shoulder to base was down to 2.014. So when you camover all you are doing is forcing the case farther into the die. This time I could not get a piece of .001 shim stock between the die and the shellholder
I run tight chambers, headspace wise. I set them up to GO gage + .003. So my normal sizing only sets the shoulder back .003 to the same measurement as my GO gage.
I also found where that brass went, when that shoulder moved back at least some of it traveled to the neck and lengthened it .003. Case head to case mouth went from 2.024 to 2.027
So back to the question" do you need to cam over". Just speaking for myself no, I can get by without stressing my press. Whether you need to is a question only you can answer. If you are running a loose chamber and getting case stretch of .007 maybe you do. It probably also adds to the consistency if you are prone not to not forcing the handle all the way down when operating the press. The little bump in the stroke being a tactile reminder
Using my lying calipers and a .400 comparitor in my Hornady case gage I did some measurements. Before sizing the distance from base to case mouth was 2.024 inches and the distance from base to shoulder datum was 1.627. I took one piece of the brass and sized it with my bushing die to 1.624.
Then I took a second piece of brass and replaced the bushing die with a body die since I do not want to mess with the adjustment on my normal die. I set the body die to where I was getting sized brass with the shoulder set back to 1.624 and took feeler gages and tried to slip them between the top of the caseholder. I came up with about .009 clearance. After I lowered the ram I turned the die down 1/2 turn and this time went camover. Clearance between the case holder was zero this time and a measurement of the shoulder to base was down to 2.014. So when you camover all you are doing is forcing the case farther into the die. This time I could not get a piece of .001 shim stock between the die and the shellholder
I run tight chambers, headspace wise. I set them up to GO gage + .003. So my normal sizing only sets the shoulder back .003 to the same measurement as my GO gage.
I also found where that brass went, when that shoulder moved back at least some of it traveled to the neck and lengthened it .003. Case head to case mouth went from 2.024 to 2.027
So back to the question" do you need to cam over". Just speaking for myself no, I can get by without stressing my press. Whether you need to is a question only you can answer. If you are running a loose chamber and getting case stretch of .007 maybe you do. It probably also adds to the consistency if you are prone not to not forcing the handle all the way down when operating the press. The little bump in the stroke being a tactile reminder
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What type press is it David ? I don't think it would destroy a press in less than 100 years of operation, it just adds some stress on the linkage pins. On a automated assembly you would see wear over time if you were pumping out 10K rounds a day, but for home use I doubt you could wear one out in 100 years. As a lifelong mechanic/machinist/electrician I avoid putting any more stress on my tools than I need to but that's just me and my cases come out just fine without it so why do it
How about adjusting the die down/in 2 full turns after touching the shell holder ?? You will not get any cam over no matter how hard you force the arm down correct ??? This is how I adjust my universal decapping die . My press arm only goes down about half of it's potential movement . How about this , thread your die up from the bottom to where you can just barely fit the case into the die . Do you get cam over with the die adjusted this way ?
To be honest I'm not sure what the question is or is about . If you allow for cam over you are not actually creating as much stress on the press as you potentially can in other ways if adjusting the die as described above . I once improperly adjusted a collet neck die then put maximum force on the handle of the press and broke the die because the leverage the press created .
I like cam over with my competition shell holders . It allows me to have a consistent stress factor on my press . These types of shell holders need the die and shell holder to make contact throughout the final sizing process . With light cam over I can consistently have the same amount of stress exerted on the linkage every stroke . If I screw the die down further to avoid cam over I personally am the deciding factor on how much stress my press has to handle . The harder I lean on the arm the more stress my press must deal with . At 6'3" and close to 300lbs I can put some real stress on my press as evidence by me blowing apart my collet neck die . Maybe a little girly man won't stress there press but we are not all built the same . Light pressure to me is like standing on the press arm to my girlfriend .
Then there's the consistency factor in your sized cases from head to datum point . As unclenick and others have pointed out . If you have a variance from head to datum of .002 to .008 and want your bullet just touching the lands . That slop of you cartridge in the chamber is how much your bullet variance to the lands will be each time the firing pin pushes the case fully forward . If your case can only move .002 then that's how much closer your bullet moves to or into the lands . If your case can move .008 in the chamber , that again is how much your bullet is moving forward as well . getting jammed into the lands that same amount .
Making hard contact with the shell holder removes all the press deflection and creates a consistent head to datum point distance . This results in the cartridge moving forward in the chamber the same amount each time the firing pin hits the primer resulting in a consistent ogive to lands variance .
Is cam over necessary , no . Does came over hurt your press , no not necessarily . It's kind of like , does cleaning your firearm hurt it ? Yes if done wrong it will every time .
To be honest I'm not sure what the question is or is about . If you allow for cam over you are not actually creating as much stress on the press as you potentially can in other ways if adjusting the die as described above . I once improperly adjusted a collet neck die then put maximum force on the handle of the press and broke the die because the leverage the press created .
I like cam over with my competition shell holders . It allows me to have a consistent stress factor on my press . These types of shell holders need the die and shell holder to make contact throughout the final sizing process . With light cam over I can consistently have the same amount of stress exerted on the linkage every stroke . If I screw the die down further to avoid cam over I personally am the deciding factor on how much stress my press has to handle . The harder I lean on the arm the more stress my press must deal with . At 6'3" and close to 300lbs I can put some real stress on my press as evidence by me blowing apart my collet neck die . Maybe a little girly man won't stress there press but we are not all built the same . Light pressure to me is like standing on the press arm to my girlfriend .
Then there's the consistency factor in your sized cases from head to datum point . As unclenick and others have pointed out . If you have a variance from head to datum of .002 to .008 and want your bullet just touching the lands . That slop of you cartridge in the chamber is how much your bullet variance to the lands will be each time the firing pin pushes the case fully forward . If your case can only move .002 then that's how much closer your bullet moves to or into the lands . If your case can move .008 in the chamber , that again is how much your bullet is moving forward as well . getting jammed into the lands that same amount .
Making hard contact with the shell holder removes all the press deflection and creates a consistent head to datum point distance . This results in the cartridge moving forward in the chamber the same amount each time the firing pin hits the primer resulting in a consistent ogive to lands variance .
Is cam over necessary , no . Does came over hurt your press , no not necessarily . It's kind of like , does cleaning your firearm hurt it ? Yes if done wrong it will every time .
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Too bad the definition of “cam over” has been corrupted by so many, including the author of the article in the OP. As a result, threads like this become a source of considerable confusion and misinformation.
Most of the following has already been stated or implied in this thread. But since it's scattered about among considerable garbage, I've summarized it below.
Essentially every press in common use today can be used to suitably size a case. In most instances it's as simple as adjusting the sizing die down as far as needed to do so. If the sizing die adjustment reaches the point where the shellholder contacts the die bottom with a case in the die, screwing the die down further accomplishes nothing beyond further stressing the press. The simplest way to achieve further case sizing (if needed) is with a shim (such as a feeler gauge) between the case head and shelf of the shellholder that normally contacts the bottom of the case head.
As suggested in a post above, adjusting an expanding die or a seating die to contact the shellholder has the potential of reducing variations in case mouth expanding or bullet seating position. Just make sure you don't apply too much pressure to the press arm.
Most of the following has already been stated or implied in this thread. But since it's scattered about among considerable garbage, I've summarized it below.
Essentially every press in common use today can be used to suitably size a case. In most instances it's as simple as adjusting the sizing die down as far as needed to do so. If the sizing die adjustment reaches the point where the shellholder contacts the die bottom with a case in the die, screwing the die down further accomplishes nothing beyond further stressing the press. The simplest way to achieve further case sizing (if needed) is with a shim (such as a feeler gauge) between the case head and shelf of the shellholder that normally contacts the bottom of the case head.
As suggested in a post above, adjusting an expanding die or a seating die to contact the shellholder has the potential of reducing variations in case mouth expanding or bullet seating position. Just make sure you don't apply too much pressure to the press arm.
Ok, we are not a bunch of PHDs trying to make a nuclear reactors, we are re-loaders.
I do thank Unclenick for all the good work he does. I don't thank Mr. G because unless you are PHD deep into it, its just confusion and not worth trying to figure out. I had an algebra teacher like that. He failed 80% of his students. The other one passed 80%
I have never presented myself as an expert, I believe knowledge about the job without being arrogant.
So what are you getting that I am not? My bases no longer crack and I don't cam over.
My groups are in the 1/2 inch area. So, with some simple mechanic it works.
As none of us is likely to get a PHD anytime soon (really late in life for me) what does all the tehnco mumbo jumbo jargon do other than make it difficult to figure out? If I understand Quantum physics does that make my reloads better?
I have forgotten all the spin in algebra (they have corollaries about this that and the other hing and makes your head spin) , but boy can I use the formulas I need to this day. Must make me some kind of sub human. Anyone ever use the left handed rule of electron flow?
I can talk all day long about the various fuel injection system on a diesel, no one could give a hoot less, how do you make it work. You put diesel in the tank and turn the switch on.
So, thank you, I will stick with my measure the shoulder, set my press to knock that same shoulder back .003 and life is good.
Oddly, those cartridge fit the gun just fine. Keep it simple, if someone wants to deep dive they can. Most of us don't.
Dang, I must be doing something wrong.
I contend you make it so complicated you do a disservice to a re-loader that all he needs to know is he measure the shoulder, adjust the die to move it back .003 or so and he can go on with life and not wreck his poor brain.
The military has made it simple, they give you instructions, you follow them, the outcome desired is guaranteed. You don't have to know the physics of it.
You start your car, do you need to know what the computer is doing or just put it in gear and it does what its supposed to?
Do you really know how your computer works?
So, it works. If you want the PHD, go for it, me, I don't have that kind of time.
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I went over an played some more and oversized a few more of those old cases.
Bear in mind that the dies are 7/8 -14 thread so that is just over .007 travel for one full rotation.
I started with the die just contacting the shell holder. Sizing was a predictable 1.623. Another 1/4 turn and it was 1.119 with a cam over effect, 1/2 turn and I got 1.615 and a cam over, 3/4 turn no cam over and measurement between 1.615 and 1.613
My final theory is that when not camming over the resistance of the case is overcoming any play in the linkage pins keeping the shellholder from contacting the die and by the time you get to 3/4 turn the ram linkage has overcame the case resistance.
Anyone have any other theories? There is no slop in the die threads once the locknut is tightened and cast iron is not known for it's flexibility. You are not going to compress steel so that rules that out.
On the linkage theory grab the linkage and you can deflect it laterally and vertically a few thousandths . It is designed with some play in the pins so that it rotates smoothly without binding. That my friends is where I believe the cam over ghost hides which is what I suspected for years but never stopped to take time to investigate
Bear in mind that the dies are 7/8 -14 thread so that is just over .007 travel for one full rotation.
I started with the die just contacting the shell holder. Sizing was a predictable 1.623. Another 1/4 turn and it was 1.119 with a cam over effect, 1/2 turn and I got 1.615 and a cam over, 3/4 turn no cam over and measurement between 1.615 and 1.613
My final theory is that when not camming over the resistance of the case is overcoming any play in the linkage pins keeping the shellholder from contacting the die and by the time you get to 3/4 turn the ram linkage has overcame the case resistance.
Anyone have any other theories? There is no slop in the die threads once the locknut is tightened and cast iron is not known for it's flexibility. You are not going to compress steel so that rules that out.
On the linkage theory grab the linkage and you can deflect it laterally and vertically a few thousandths . It is designed with some play in the pins so that it rotates smoothly without binding. That my friends is where I believe the cam over ghost hides which is what I suspected for years but never stopped to take time to investigate
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thanks 7/8 - 14, I had just divided 1 by 14 to get the .071 number and had 1 stuck in my head
Yeah I keep mine really tight, I just bought 100 6CM cases from Alpha. Great cases but the factory resize was way short for me with .005 clearance. After first firing I will only bump em back .002 - 003 from the GO gage measurement
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I would bet not , Was it for the few cases used that likely had same head stamped and same number of firings , Sure . Now run that same test but this time use Winchester cases Lapua cases and LC cases all with different amounts of firings/ work hardenings . See if your head to datum point measurement is as predictable now .
I can tell you it won't because I ran that very test 5 years ago and my case head space
measurements were all over the place depending on the manufacture of the case and how many times it had been fired . It also changed if the cases were freshly annealed . resulting in me constantly needing to readjust my die to only bump my shoulder back .002 . I've posted these pics many times in threads talking about this very thing and will again here .
Here is the die set up exactly as you described , screwed down to where it's just touching the shell holder when not sizing a case . Keeping in mind that this position is in cam over so the shell holder is actually pulled away a little yet still touching .
Here is that same setting sizing a 308 case . As you can see the flex in the press and linkage has now allowed a gap to form between the die and shell holder when sizing the case .
I don't remember the exact gap size but know it was at least .008 . Meaning sizing that case with that amount of firings my press deflects .008 . A freshly annealed case may only cause the press to deflect .004 . Meaning if I keep my die set the same in the press depending on the cases I'm sizing there can be an variance of .004 from head to datum . So if I'm only trying to bump a shoulder back .002 on a case that deflects my press by .008 I won't bump the shoulder at all and will need to re adjust the die .Or place a feeler gauge under the case in the shell holder
Which is incredibly time consuming because you have to measure every case every time you size it to know what size feeler gauge to use . This is why I use the Redding competition shell holders . They are designed to have the die and shell holder make contact removing all that press flex . Actually what they do is force the press to flex past what your case can make it flex resulting in a very consistently sized case from head to datum point because the press is over powering the cases ability to spring back .
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I am not interested in ruining any Lapua or Alpha brass, those Hornadys was range pickup where a guy was sighting in his hunting rifle and was not a reloader. I just wanted to see where the flex was and now I know. It was entertaining but I have had quite enough of dial indicators and feeler gages for awhile
Thinking about it though I would guess the difference between brands would be due to the properties of the brass. I would also guess changing presses would change readings also. The less flex in the linkage the less of a gap, more leverage would also result in the same.
Bottom line is I have my dies set where I want them and do not need to stress the linkage. I use .002 - .003 setback, rounds always chamber and I get long case life and that makes me happy
Thinking about it though I would guess the difference between brands would be due to the properties of the brass. I would also guess changing presses would change readings also. The less flex in the linkage the less of a gap, more leverage would also result in the same.
Bottom line is I have my dies set where I want them and do not need to stress the linkage. I use .002 - .003 setback, rounds always chamber and I get long case life and that makes me happy
Correct , to include wall thickness as a factor on how easy or hard the case is to size . It's why I suggested test Winchester cases . In 308 they are my lightest cases by 10+ grains which means thinner walls then the rest .
Yep , and I think my Hornady press has more flex then others if not most others .
Also the slickness of the lube you're using can effect press flex .
Cam-over in torque wrenches are pretty much like pushing a weight over a peak then when you force is at its zenith it goes over the peak and input force drops.
It’s not an uncommon concept lots of things use the cam overcenter concept.
https://www.rockler.com/cam-clamp?s...MIp6TQ4Jzo3wIVk-DICh3UOw-jEAQYBSABEgKJvPD_BwE
In a press the idea is a little more handle travel would get you to the same ram/die position (minus stretch & linkage takeup) vs a positive stop where the operator might not hit the stop.
From the OP’s link.
That is cam-over and as the press was designed the only way to not cam-over is to not make a full stroke. You can run it empty or run a die down and put it in a bind but both will still cam over if you can complete a full stroke.
I've been using Wilson Case Gages for the last 50+ years to adjust my sizing dies. I have dies made by Lyman, Herters, RCBS, Dillon & Lee, plus shell holders from all of these manuf.'s. Using the Wilson gage allows me to use most any shell holder with any of these dies. The Wilson gage also shows when a case should be trimmed and by how much. They're well worth the money.
Lastly, blythely, screwing a sizing die down to contact the raised ram/shell holder, plus an 1/8 to 1/4 more will not work with all cartridges, RCBS' instructions notwithstanding. Several of my lever actions, for instance, have overly long chambers (long in headspace), and require longer cases than what is indicated by the case gage, in order to prevent head separation. In these rifles, I size to the extent that I can chamber the case, and feel just the slightest bit of resistance as the lever closes. This is sizing to meet a specific gun's needs. Here's Wilson's description of their case gage.
https://lewilson.com/case-gage/
YMMV, Rod
Lastly, blythely, screwing a sizing die down to contact the raised ram/shell holder, plus an 1/8 to 1/4 more will not work with all cartridges, RCBS' instructions notwithstanding. Several of my lever actions, for instance, have overly long chambers (long in headspace), and require longer cases than what is indicated by the case gage, in order to prevent head separation. In these rifles, I size to the extent that I can chamber the case, and feel just the slightest bit of resistance as the lever closes. This is sizing to meet a specific gun's needs. Here's Wilson's description of their case gage.
https://lewilson.com/case-gage/
YMMV, Rod
My Rockchucker has a positive stop. It's a lag bolt screwed into the table that stops the press lever just short of full stroke. Without ever hearing of "cam over", it was put there to keep from stressing the press linkage too far at it's furtherest down stroke. There is still flex, as when a die is turned down against the shell holder, then after a case is inserted the die/shell holder has a gap. Depending on need, that gap can be reduced/eliminated by turning down the die slightly. An example of this is to ensure that semi-auto pistol cases are sized as far down as possible. Another example is sizing down a rifle case fired in Military spec chamber down to fit in a tighter chamber. Reloading for differing styles of firearms/brands of brass, the sizing die is adjusted each time.
All these years never really understood "cam over", and still not sure. It sounds like an option some use.
All these years never really understood "cam over", and still not sure. It sounds like an option some use.