Cam over presses

[ubetcha]

I was just doing some reloading and a thought occurred to me regarding press ram camover. Does anyone happen to know of any advantage or disadvantage of the cam over effect. I have a Hornady Pacific press that has cam over. When adjusting dies that require shell holder contact, one has to ensure that the highest point of the ram shaft is before the handle is all the way down. If adjusting for Lee collet dies, one also has to take care not to over cam on the sizing dieas not to damage the die or possibly crush the case. I think Lee presses do not have cam over, but I'm not sure about other brands except my Hornady.


**** auto correct keeps changing cam to can.

[jimkim]

I don't with the presses I have now, but I did with my old Lee turret press. I have never noticed a difference in the finished round. Some swear by it. To me TDC is TDC is TDC.

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[David2011]

Agreed, tdc is tdc. When adjusting cam over should be a gentle bump. Hard cam over adds nothing but major stress on the press frame. It occurs at the point of maximum leverage so it can be difficult to appreciate how much pressure is created.

[Livin_cincy]

I saw Cam Over explained that it predates the common use of Carbide Dies.
- Steel Dies & Lubed Cases required it.
- Carbide Dies are more common today. You can also harm the carbide insert with cam over.

[mdi]

Personally I can't see any need. The cartridge/case will only go so far into a die, and if one can make sure if it does every time, either against a solid stop, or beyond top dead center, then it's working to it's designed purpose. Perhaps one cannot regulate their actions on a press, short stroking or cannot repeat the action, the the "cam over" is a solution. I don't have any presses that need any slop taken up in the linkage and none "cam over"...

I believe "cam over" also puts too much pressure on the linkage leading to excessive wear...

[243winxb]

RCBS has said, the shell holder contacting the botton of a steel die, will help die allignment. Lock die with light cam over. Also removes slop from the linkage. I measured the difference of .001" to .0015" more shoulder set back in 243 win, with cam over. Compared to just touching.

Some like to only bump the shoulder back .002" This means the shell holder and die may not make contact. The amount of the bump is not consistent. To much or to little shoulder setback.

To have more control , with cam over and shoulder bump , Redding makes the Competition shell holder sets.

For those that care.

[labradigger1]

I cam over when bullet Swaging in an old rcbs 2A. Allows more repeatable finished weights when squirting.

[odfairfaxsub]

I used to cam over. I was taught to. When I moved and finally re-set my stuff up and got back into my groove. Surprisingly not reloading a rifle cartridge in 2 years I plumb forgot about cam over haha. Now I believe what the gentleman above said best speaks for me sizing brass; “tdc is tdc” and just like the person above said as well “if you can’t or have a hard time being repeatable w a process cam over is good”

I’m not having a hard time finishing my strokes

[flashhole]

To cam or not to cam ... that is the question.

I do very little pistol ammo, automatic or revolver.

I make a lot of rifle ammo. Let's focus on resizing brass.

I have compared presses with the cam over feature (Redding Ultramag, RCBS Rockchucker) to presses with a hard mechanical stop that does not allow cam over (Lee Classic Cast).

The issue (not a problem) is shifted to another part of the resizing process. With "cam over" you are literally, mechanically forcing the sizing system to extract maximum mechanical advantage to obtain an objective.

With a hard mechanical stop (Lee Classic Cast) on the sizing stroke you can shim in the shell holder, under the brass, to control the degree of shoulder push back. Or you can use a set of Redding precision shell holders that perform the same function as putting a shim in the shell holder under the brass. The Redding shell holder is much simpler.

I like the non-cam-over method better and do most of my resizing with the Lee press.

Variables still exist. For precision and controlled results one must anneal the brass to ensure it will resize to the same degree piece to piece to piece.

[Bent Ramrod]

The cam over really comes into its own with full-length resizing of heavy, heavily-loaded, high intensity cases and range pickups fired in sloppy chambers, X-Treem case forming and bullet swaging. The top-dead-center stop is especially valuable for swaging; otherwise, you have to “feel” the extent of point forming or core seating. For reloading, the die settings ensure the stops and depths. It makes normal full-length sizing easier, but isn’t absolutely necessary.

Yes, if you set your carbide die so the shell holder mashes against it at the end of the stroke, the ring will eventually break.

[Iowa Fox]

I actually like both styles of presses. To get the most out of the Lee collet neck sizer a cam over press is the best to get just the right amount of tension on the neck. Google John Valentines instructions for the Lee collet dies. Another press with just a slight amount of cam over gives me the least amount of run out using Redding & Forster micrometer seating dies. Buy as many presses as you can afford or have room for.

[1bluehorse]

Some presses, usually older ones, had cam over built in. I had an old Pacific Multi Power as you do and it had it built in, ram would "drop" from TDC when handle went to bottom of stroke. Probably a quarter inch or so as I recall, long time ago, press was circa 1976. What most folks are talking about with presses that don't have it built in isn't "true" cam over to me, not sure what it should be called but you can get a "bump" at the end of the ram stroke by seating the die deeper after it touches the shell holder. (Not for carbide dies) Is this actually cam over? Maybe, works the same I guess. Most rifle size dies tell you to do just that, seat until touches shell holder then lower ram and turn another 1/8th turn. This will induce what most call "cam over", I realize most know this but I get a bit exasperated with some of the discussions about it. Some say screwing the die beyond shell holder "kiss" doesn't garner anymore sizing of the case, perhaps not of the case but it will definitely move that shoulder more. Maybe not a whole lot but it will move it. It's probably just taking the "slack" out of the press, at least that's what the popular consensus is. If you really want to know for sure, and not what us "internet experts" say, just try it for yourself. All you need is a set of calipers and a way to measure from a datum line on the case shoulder. A thousand guys can tell me it won't do that, well it will, I've done it and measured the difference.

[1hole]

"Cam over" is MUCH misunderstood. Ditto for using Redding's excellent Competition Shell Holders and straight wall case sizing.

The lever and toggle block cams, or rotates, the ram up to Top Dead Center, any further lever-to-toggle rotation is "camming over" and the ram starts to move down; that cam-over occurs even if there is no die or case in the press.

IF the user has a limited rotation press, he can have difficulty knowing if his case is stopping from hitting the press' fixed travel stop or it's just a tuff case. Allowing the toggle to over rotate just a bit allows the user to feel the roll over point. The change of ram direction is proof the toggle has cammed over and passed TDC even if the ram and shell holder have not touched. That useful bit of tactile feed back is the ONLY reason some makers design cam-over in their loading presses.

Jamming cases as far into an FL die as they will go will certainly "Full Length Size" them but, in my opinion, such sizing is a noob practice because it insures maximum case stretching each time it's fired. As hand loaders we have the option of making custom loads (including custom FL sizing) for our own rigs, not for every rig that has ever been made for that cartridge!

I started "reloading" by the numbers in '65 and started "hand loading" a couple years later. That means I first sized all my cases as deep as they would go, then I decided to size my cases just enough to allow snug but easy chambering and have never looked back. And I've never had a case head separation, nor any incipient signs of an impending separation; some of my hot loaded .243 and .22-250 varmint cases have been reloaded +/- 20 times, and that with a single neck trimming.

Redding's Competition shell holders do not allow cases to enter deeper inside a sizer. Instead, the Comp shell holders have steps that DECREASE the possible amount of sizing, which makes setting up my FL dies quite easy after I learned which shell holder goes with which sizer for a particular rifle.

Using carbide or steel straight wall sizers, I know of no situation that benefits from "FL" sizing hard to the shell holder as if they are bottle necked. In fact, IME, that's excessive sizing, especially so with carbide dies, because it promotes rapid case failures by early splits in the over-worked mid-walls. Leaving something like a 3/16" to 1/4" gap between the shell holder and die usually works well for me.

[David2011]

More ramblings from your truly. AFAIK a Dillon won't cam over and it's never been an issue. I use Dillons a lot, mostly for handgun cartridges. They just bottom out and everything is peachy. Maybe the difference in the design of the links is why they work so well just bottoming out. Lots of leverage in a 550 or 650. I've never used a 1050 but imagine it has gobs of leverage. When I had a Square Deal B it took more effort than the bigger presses.

Most of the rest of my loads are on my RCII. I tried adjusting it for the shell holder to bottom out against the sizing die without cam over. With straight walls IMO it makes no difference. Most of my straight wall loading on the RCII is .44 Spec/Mag and .45 Colt, neither of which is loaded in lots of more than 100 at a time. Because of the significant additional leverage at the bottom of the stroke I felt like it took more effort to bottom out without cam over. Straight walled large bore pistol cartridges can take a fair amount of effort to resize if shot at high pressure. The toughest cases I've ever resized were .50 S&W. They were worse than .45-70 or .375 H&H. Mind you, I adjust for just the minimum of cam over feel; just enough to know it happened. More than that stresses the press unnecessarily.

[Petrol & Powder]

I'm in the TDC is TDC camp.

A press that cams over will push the casing to its maximum depth in the die and then pull it back down slightly (maybe depending on the amount of cam over and tolerances), then push it back to TDC before pulling the casing back down.

When everything is in compression on the upstroke of the ram TDC will be defined by how close you can get the top of the shell holder to the bottom of the die. When you pull the ram back down, everything is in tension. The clearances necessary will result in a small amount of "slop" (the tolerances between the pins, links, bell crank, etc,; plus the shell holder to ram fit and finally the casing rim to shell holder fit).
When you compress all of those components together on the up stroke you're going to get a TDC somewhere - and that's it. There is no TDC plus a little. I don't see what cam over does for you.

[Harter66]

I have a rifle that knows the difference ............

Ever use a torque wrench ? Ever used one with a torque muliplier or a cheater extension or even a crows foot ?
With a heavy mechanical background , this is like the torque tube/flex needle vs click type battle . In my thinking there is no contest and if you've ever torqued 110# head bolts with a flex pointer type wrench you know what I mean .
I've never cared for mechanical dead stops outside of minimum throttle and timing stops . Get a little wear , dust , grit , over or under lube , or adjust a die a touch too deep and you don't know if you're there or just up against a mechanical feel stop . Believe me I've set a lot of torque to plus or minus 5# because my strength and muscle hold couldn't hold 110# any closer on the spring tube and needle .
I have a set of 06' dies with 2 sizers . One is set up by the book , ram up spin down to touch , ram down , 1/4 turn down , set the lock ring . Believe it or not on the RCII that will occasionally leave a gap between the shell holder and die with fat brass but only for 10 seconds or so . The second die was set up to short size for the fattest chamber and the ram stopped probably .08 off the die under load . Some of my 1x brass needed that 10 second hold to fit in the tightest chamber of 3 . I have to say I think that would have been a tall order on a dead stop no cam press to hold tension at full contact stop for 10 seconds every pass on 100 pieces .

I do have a cam over press that has significant movement on the cam over . Seriously if a different die is screwed down to touch all the way up and over the ram is mechanically locked up . I don't use that press for sizing or seating ammo just sizing bullets . The 3 RC tanks and Big Max don't cam over like that probably no more than 1-3° . I'm sure there is some down movement after the cam over but for my needs it doesn't matter except when it does .
Just like the click type torque wrench that is argued to go over torque when it clicks so does the cam over press when it cams over . But I'll take the cam over hold on the big presses even if I don't use it all the time just like I'll take the click torque wrench not for the 120 inch pound rocker cover screws but for the 90-140 ftlb assembly bolts and nuts . Sure it makes the 30# and less torques easier to hit too and after you've screwed down 10,000 spark plugs you do get a feel for it but there's nothing like a confirmed load hold for repeatability . Then you can blame annealing , lube , die condition , expanders , push / pull on the necks , mechanical alignment of the press/dies , ram/frame wear , lock nut flex , seating stem deflection , neck concentricity , locking lugs , bolt face , chamber/bore alignment , rifling type , roll marks , dove tails , twist rate , crown , center of gravity , center of air flow , slumping , and zinc .

[1hole]

Adjusting dies "by the book" is for noobs who are just starting to reload; it insures that all (most?) of the loaded ammo will be accepted and fired from all firearms ever made in that caliber. That's not a bad thing but it's not true that turning to touch and adding another magic bit of turns makes it "the right way" to resize because that's the instructions. Die maker's instructions are a good place for beginners to start but ... why stay at the starting point forever?

Fact is, our dies and weapon chambers vary. Thus, religiously following any maker's "rule" of noob die adjustment as if it's eternal scripture from on high automatically defeats a significant part of a competent handloader's efforts to obtain the best possible end of his results. I believe it's much better to FL size cases to fit OUR OWN needs, not everyone else's!

[Kenstone]

All one needs to do is setup a sizing die that has needed a lot of press pressure to size before, to just touch the shell holder.

Then size a case and measure any space between the shell holder and die at TDC with a feeler gage.

Any gage the fits will represent any press "spring/stretch/flex/deflection" from the force of sizing.
jmo,

[flashhole]

What? No discussion of annealing or spring back?

[Kenstone]

What? No discussion of annealing or spring back?

Have at it