Press toggle or cam-over

A

afrench

Member
During full length sizing, how important is it for a press to ‘toggle’ or cam over, or not to?

I’m talking about use in precision rifles here, not granddad’s 270.

I never really thought about this until recently and asked a couple of people whose opinions I respect. Of course, I got conflicting answers… so, I thought it may make for a good discussion.

I’ve used a partner press since I started a few years ago, so I don’t know anything else when sizing ppc sized cases. Obviously, they work fine as I’ve probably seen more of those used at the matches I’ve attended than anything else.

I thought about picking up a Lee classic cast press since a lot of guys use them for bullet making operations due to their strength and straightness. In reading about it, it won’t cam over or approach ‘TDC’, for lack of a better term, without mods. After looking at my partner press, it doesn’t either.

I know the Lee would be overkill for sizing the ppc brass, but I’m interested in if it can make better, straighter ammo and ultimately shoot smaller aggs.
 
Its a mechanical advantage just taking the press to a hard stop is hard on you. Plus most custom ppc dies will bump WAY too far if you didnt use the cam over like most br dedicated presses have. I have a partner press I have set up to be portable and it has the cam over at the top. Maybe some are different.
 
I have a press that does not cam over, and a couple that do. They both work sizing PPC cases. Shoulder bump is a matter of die adjustment on both types. Cam over results when the ram starts back down a bit before the handle linkage stops it. It can happen because of how a press is built, or because of high levels of force stretching press linkage. As long as the die is properly adjusted for the press and task, there should be no problem. My experience has been that I have had to have some material taken off of the top of my PPC shell holders to get dies to bump. My fired cases have been compared to a headspace gauge and they are a little longer to the shoulder, within tolerances, so the need to modify shell holders has not come from short chambers.
 
Boyd ,,,it sounds like your chamber is too short,,,that is why you have to shave the shell holder,,,it the chamber was long you would have to leave an air gap (space) between the shell holder and the bottom of the die,,,or the die culd be tooo long,,,either way there is a mismatch somewhere,,,Roger
 
As I said, I have compared the shoulder to head measurement of my fired brass to a proper headspace gauge, and my chambers are not short. From what I have read and discussed with other PPC shooters, what I have had to do is really not all that uncommon. I suppose that I should add that I have never had a case separation in any of my PPC brass, and that I set up my die each time that I start a reloading session, limiting my shoulder bump to .001 from a tight case. As the brass becomes more work hardened the die must be turned into the press to compensate. Once when I did not check till I had sized a few fresh cases, I found that the setting that worked for my old brass, bumped the new stuff about .0035. That is why I reset each time now.
 
I really don't know what Y'all are talking about but I'll say this....Your press handle needs to go all the way so you'll be consistent with whatever you're doing. It's just the easy way! Folks set them up to have a bit of "cam" just to make sure but a lot, or no cam at all, is not the best method. In other words, set it up so you don't have to think about it...there's too much other stuff that needs the thought

If I missed what this thread is about, just ignore the post and say something like "Man, Wilbur is almost gone these days". That would be a true statement. Alternatively, if what I said applies you can always say...Man, that darn Wilbur really knows what he's talking about!
 
Wilbur said:
I really don't know what Y'all are talking about but I'll say this....Your press handle needs to go all the way so you'll be consistent with whatever you're doing. It's just the easy way! Folks set them up to have a bit of "cam" just to make sure but a lot, or no cam at all, is not the best method. In other words, set it up so you don't have to think about it...there's too much other stuff that needs the thought

If I missed what this thread is about, just ignore the post and say something like "Man, Wilbur is almost gone these days". That would be a true statement. Alternatively, if what I said applies you can always say...Man, that darn Wilbur really knows what he's talking about!
Click to expand...

Wilbur, would it offend you if i said both?? haha.

here's what i'm talking about. i probably could have done a better job of explaining, and it may not amount to a hill of beans for this purpose.

here is my press with the handle all the way down.



and, from a different angle.



notice the pin at the bottom of the linkage is no where close to the centerline of the ram when up against the mechanical stops about 1/3 way up the linkage.

one thing that got me thinking about this is after a several firings on each piece of brass, i'll have 2 or 3 out of ten that i can feel the brass when closing the bolt. and, yes, i'm aware that i have to adjust the die down as the brass hardens.

one thing i need to do and haven't yet is measure the case length with a gage using different amount of force on the handle at the stop. i feel like i'm being consistent with the force at the bottom when sizing, but who knows.

anyway, in theory, if the press got closer to TDC, wouldn't that give the most consistent results?
 
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If you back off die will linkage move closer to top of stroke? And to answer your question the closer you get to top off stroke you gain leverage and it will be more consistent.
 
geo.ulrich said:
If you back off die will linkage move closer to top of stroke? And to answer your question the closer you get to top off stroke you gain leverage and it will be more consistent.
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george, the die never touches the shell holder, so, no.

that's what i was thinking.

thanks.
 
I don't think I understand the question just yet...and that bothers me a bit so play along if you will. It seems that you have the option of adjusting the die to any handle position (for discussion purposes)...so why not just adjust the die such that you go all the way to the handle stop...the bottom if you will?

I know there's something about this that I don't understand. What's that thing at the bottom of the press do? Looks like it does something cool....

AND...no...I'm too stupid to offend that quickly. I thought about putting one of those "smiley faces" here but decided there's no sense in lightening the truth.
 
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This is a very interesting question. I've had the same conversation with a few guys, and like the original poster, I've had conflicting answers from shooters whose opinion I respect. One of them was adamant that it cam over, giving the brass a double tap (as I call) it, while another was just as opinionated in that it not "double tap". He stated that if he wants a double tap, he'll run the brass twice. I myself have not used a press (with a PPC) that cams over, but I do size my brass twice in the same stroke, sizing the brass once, backing it off a bit and sizing again. I believe this gives the most consistent sizing, making each piece as close to the same headspace as possible. So given that a cam over press may be the best way to go.
 
A couple of other variables with regard to the amount of bump at a given die setting are amount of lube, and dwell time at maximum ram extension. I prefer that a press not cam over, but I can work with those that do. Modification of linkage stops is required if one wants to do away with camming over. If you ram goes back down a bit, after it reaches its highest position, before the stop is engaged, your press has cam over.
 
Wilbur said:
I don't think I understand the question just yet...and that bothers me a bit so play along if you will. It seems that you have the option of adjusting the die to any handle position (for discussion purposes)...so why not just adjust the die such that you go all the way to the handle stop...the bottom if you will?
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right, that's the problem. even though i have the FL die in place, the press is against the mechanical stops in the linkage in those pics. i don't like the shell holder to touch the die so i grind off just enough so that it doesn't. i probably have .010-.015" clearance between the two with the handle all the way down without the case.

Wilbur said:
What's that thing at the bottom of the press do? Looks like it does something cool....
Click to expand...

ha, yeah, that's just one of my expander dies used to hold the press up level for the picture. sorry to disappoint.
 
GPat said:
This is a very interesting question. I've had the same conversation with a few guys, and like the original poster, I've had conflicting answers from shooters whose opinion I respect. One of them was adamant that it cam over, giving the brass a double tap (as I call) it, while another was just as opinionated in that it not "double tap". He stated that if he wants a double tap, he'll run the brass twice. I myself have not used a press (with a PPC) that cams over, but I do size my brass twice in the same stroke, sizing the brass once, backing it off a bit and sizing again. I believe this gives the most consistent sizing, making each piece as close to the same headspace as possible. So given that a cam over press may be the best way to go.
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it seems to me the best of all worlds is for the press to just go to TDC. i don't know if a double hit is desirable for brass sizing. it might be for squirting cores but i doubt it is good for sizing.
 
Boyd Allen said:
A couple of other variables with regard to the amount of bump at a given die setting are amount of lube, and dwell time at maximum ram extension. I prefer that a press not cam over, but I can work with those that do. Modification of linkage stops is required if one wants to do away with camming over. If you ram goes back down a bit, after it reaches its highest position, before the stop is engaged, your press has cam over.
Click to expand...

i can see how those other things may come into play.

i have some experimenting to do.
 
You can't make your shots more accurate or fit your rifle any better other than pushing the handle all the way down and adjusting the die to mash the case around. You can get a better die or what ever you need to make the action work more smoothly but the rifle won't shoot any better as is. Working more smoothly is in fact better. The rifle won't shoot more accurately but you can get more shots in a shorter time....which often equates to shooting better.

I'm disappointed that other die wasn't something slick you came up with! Dammit!
 
ha, yeah, that's just one of my expander dies used to hold the press up level for the picture. sorry to disappoint.[/QUOTE] That's to funny. I looked at the picture long and hard to see if I needed one.
Call me slow. Tom,
 
Wilbur said:
In other words, set it up so you don't have to think about it...
Click to expand...

Man, that darn Wilbur really knows what he's talking about!

One of the benefits of cam-over is to make sizing consistent. Everything flexes, including mechanical stops. If you drank an extra cup of coffee, or are mad at the dog, you might push the handle with more force than normal. For a press that doesn't cam-over, this results in the stop flexing, the shell holder rising a little more, and a little more sizing. With cam-over, the shell holder reaches its highest point before the stop, so even if you push like Arnold, the shell holder just drops a little extra and it doesn't matter for sizing.
 
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