Cam-over hornady single stage press

dbomb · July 28, 2010, 04:20 PM

I have an interesting problem, I have been reloading .45 for a while. I also got some dies for my .223 and my 300 winmag. After lots of reading I want to get my headspace correct and custom to my rifle.

When I try to shoulder bump the cases. My dies for the .300 win mag (redding body die) wont do it, unless I go lower than when its touching the shellholder, which I think its called cam-over.

The same thing is happening with my .223, after I shoot the case would get suck in the chambe, after a few posting I was told i had to bring the FL sizing die lower ( hornady dimension FL sizing die) which it works, but when I pay close attention again is caming over to get it where I want to.

So even though its working, I dont feel too comfortable cam-over every single time. I think something will eventually give. Is it OK? or do i have to get something like the redding competiion shell holders?

Thanks this forum is full of good stuff, keep it up.

demigod · July 28, 2010, 04:29 PM

I think I have a resizing die that does that when I dry cycle my LnL single stage. I guess it depends on how heavy the cam over is. One of my dies does it slightly.

Are you using a headspace guage for your rifle brass?? I set my dies up so the resized brass fits perfectly into a headspace guage. I also check the headspace guage by running known good factory ammo through it. That way I get a thorough cross check on the press and the guage.

dbomb · July 28, 2010, 04:38 PM

I use the Hornady Lock N Load Headspace Gauge Kit, for my .300 I went last weekend and shot about 20 rounds and measure them. then substraced .002. and came up with the number. 2.271"

I got the gauges because after a while the bolt was hard to close and sometimes the bolt wouldn't open after firing. So i wanted to know exactly what size I needed my cases to be.

F. Guffey · July 28, 2010, 05:36 PM

Terms I do not use, datum, datum line, bump and cam over, I have at least 4 presses that cam over, not one of the 4 is an RCBS, all my RCBS JAM OVER, lock up and stop, . I am one of the few with gages that can measure 'cam over', if others could they would stop talking about it. I do not have a Hornady (I have a Pacific) if I did I would measure it for CAM OVER.

A press that cams over does not bump, it bump-bumps as in it bumps on the way up and again when the ram reaches the top and starts back down before hitting the maximum travel, so it bumps again on the return trip down, the RCBS A-2 press is THE CAM OVER PRESS, no tools necessary,

Jam over or cam over, who knows, for most it is the unknown, for years the amount of travel that is not used by the press to size the case is used to stretch, flex, deflect the press described by the term STRAIN, again I have a strain gage and a deflection gage and the dial indicator can be set up to measure deflection (and cam over), just a guess but I believe there are those that jam/cam the press over every time they size a case and have been doing it for years without harm to the press.

Again I use the companion tool to the press tool the feeler gage.

F. Guffey

Bill Daniel · July 28, 2010, 08:26 PM

dbomb, the instructions for my LNL stated that the ram should be raised all the way up and the sizing die screwed down to it till it touched and then a quarter turn or so lower before locking it in place so that the press would "cam-over" at the top of the stroke.
Bill Daniel

dbomb · July 28, 2010, 10:12 PM

So i guess its OK to cam-over. I was concern that I was doing something wrong. To get the measurements that I needed to FL size my cases, and match my headspace measurement I had to cam-over the press.

So Looks like I'm back at mass production

F. Guffey · July 29, 2010, 07:18 AM

dbomb, yes it is, it is OK to jam-up, lock-up and or put the press into a bind if it is necessary or out of habit or because the instructions say you gotta do-it, RCBS instructions say the same thing, they know better, they make the press but omit the change if directions as in up, stop and return, the RCBS ram goes up then stops, goes into a bind, the bottom of the ram kick out and the ram tilts etc. but never returns (changes directions), SO, the RCBS Rockchucker does not cam over, it goes into a bind.

How tough is the case to size? Dose the case have that much resistance to sizing? Even after that cramming, jamming and crushing, flexing, deflection did the case get sized because the press is tougher than the case, or did the case win and if it did how could the reloader determine the amount of of case that did not get sized? If the case does not get sized during sizing with the 1/4 additional turn the part of the case that is not sized must be sticking out somewhere.

I know, spring back, it's spring back, not on my cases, not on my presses, most of my cases have no memory of what they were when they started, 30/06 to 257 Roberts? The only memory is the reminder on the head of the case, again I check head space first, then adjust the die to size/form.

I do not work a press any harder than required, I do not have a problem with sizing a case, I do want the case to fit the chamber, sometimes I am required to add .010 thousands to the length of the case from the head of the case to the shoulder, I can not do that by camming/jamming the press.

F. Guffey

dbomb · July 30, 2010, 09:06 PM

No, there isn't much resistance. I follow the LNL dimension dies to set up the FL die. Then started to screw it down till I got the headspace I needed. It turned out to be 1/4 turn more, for my .223. I haven't done it to my .300 to find out how much it goes down. But again looks like its all good to go. Thanks for the all posts and advice.

wncchester · July 31, 2010, 12:29 PM

Goodness.

Cam-over refers to toggle block and ram over-travel. It's the same even if no die is present unless we block the ram with a die adjustment.

As the lever/toggle link pushes the ram up, they will reach the point of top-dead-center where lever pressure has had it's maximum effect. Any further lever/ram travel after TDC is "cam over" and, if it's designed for that, the ram will typically travel back down just a tad. In effect, it means nothing special. We can screw dies down in any press until they stop the ram before TDC and get exactly the same result as with other presses that have a built-in travel stop that prevents camming over.

Die "instructions" saying to turn sizer dies down to contact and some additional magic 1/4 turn, etc, are great simplifications. That just makes sure noobs will get cases that will chamber in any rifle ever made in that caliber and but it certainly isn't the best way to do his FL sizing! A major (potential) advantage of handloading is to custom fit our ammo to our own weapons, I couldn't care less if my loads don't fit any others!

Individual presses and dies require slightly different amounts of "extra" turning for best fit. It's up to the individual reloader to learn exactly where he needs to position his sizer to produce sized cases that shoot best and last longest. The type of press operation - cam vs. no cam - makes no difference in accomplishing that.

PA-Joe · July 31, 2010, 05:18 PM

You can also remove 0.001 from the shell holders using 400 grit paper. A little at a time until your shoulders are bumped back to where you need them.

demigod · November 1, 2010, 11:31 AM

I recently discovered that on my LNL classic there are chunks of the lugs on the PRESS BUSHING that have broken away!

I need to take a close look at all my die bushings to see if there's anything going on with them. But I have a little bit of cam over on my 9mm die when there's no brass in the press. When I'm actually resizing a piece of 9mm, the cam over isn't happening due to the resistance of the sizing die on the brass.

I'm wondering if the cam over didn't damage the Press bushing.

PA-Joe · November 1, 2010, 02:08 PM

Just wondering if you are all using Hornady Shellholders or are you using LEE or RCBS? The shell holders have different deck heigths and that may be why you are not bumping the shoulders back enough. There was a case a few months ago where changing the shellholder corrected the problem.

demigod · November 1, 2010, 03:39 PM

I'm using Hornady shell holders.

demigod · November 1, 2010, 07:06 PM

demigod · November 2, 2010, 08:01 AM

Quote:

Nothing wrong with "cam over" I have been doing this for over 40 years on the same Rock Chucker press.

That's good to hear. I sent Hornady a message last night. Hopefully I'll hear something soon.

demigod · November 5, 2010, 11:24 AM

Talked to Hornady today. They apparently had a vender supply them with some press bushings that have been chipping/breaking. They're sending out a replacement today!

Edward Horton · November 5, 2010, 01:50 PM

RCBS makes the Precision Mic for measuring your cases before and after being fired to properly set up your resizing dies.

The "zero" on the gauge represents minimum "rifle" headspace.

The average factory loaded ammunition is .002 smaller than minimum headspace to ensure the cartridge will chamber in any rifle.

"YOUR" fired case will be longer and this is why you can neck size only and not over resize your brass and make your cases last longer. When full length resizing for "YOUR" rifle you only need to push the shoulder of the case "back" approximately .001 to chamber without any bolt resistance on closing.

When partially full length resizing you can actually make the case shoulder "LONGER" than before it was fired. When full length resizing the brass case has only one direction it can move and that is "upward" and the shoulder of the case will be pushed forward.

"Partial" full length resizing is used to only push the shoulder of the case back far enough to chamber in "YOUR" rifle and "NOT" over resize the case.

"Cam over" or making sure the base of the full length resizing die is making firm hard contact with the shell holder makes sure the cartridge will chamber in "ANY" rifle after sizing, because you have pushed the shoulder of the case back below minimum headspace.

This is why they make custom shell holders that are "LONGER" than a standard shell holder and allow you to adjust your "cartridge" headspace.

Also remember to place a lubed cartridge case in the shell holder when adjusting your dies to "center" the die in the press before locking down the die lock ring.

brickeyee · November 5, 2010, 02:31 PM

Quote:

all my RCBS JAM OVER, lock up and stop

Say what?

'Cam over' refers to the toggle block linkage driving the ram going through a zero length lever arm.

If the ram stops well before that point (maximum height) the press will indeed simply stop, continued force is going to be internal loading unless something breaks.

If the the ram stops near the point there is enough force and flex available to have the toggle block go through a zero length lever arm the ram starts to move down after reaching maximum.

Cam over has just occurred.

It does generate a huge internal loading on the press for that brief bit of travel.

Before the RockChucker patent (US#2,847,895)with the toggle block, presses used simple leverage.
The RockChucker was the first press to use a toggle block and allow the lever arm to go through zero length at maximum ram extension, generating more than sufficient force to size cases rather easily.

wncchester · November 5, 2010, 03:39 PM

"...using Hornady Shellholders or are you using LEE or RCBS? The shell holders have different deck heigths "

Mr. Horton is correct, the SAAMI design "deck height" of all shell holders is 1/8th inch, .125". All dies are bored to accept that depth as part of the die's chamber. In some 40+ years I've never had a need to reduce a die or shell holder but, if I did, I would change the die mouth since that's likely where the problem is.

All cam-over in a press means is the toggle link has rotated passed top dead center and the ram has started back down. There is no mechanical value in cam-over vs. simply stopping at the top of the ram's travel.

The mechanical advantage of a compound toggle system comes from the swinging arms moving the pivot pins closer to the line of force as the toggle rotates; that moving fulcrum principle is what vastly multiplies the compound toggle leverage compared to the older simple toggle system

Edward Horton · November 5, 2010, 03:54 PM

Happy RCBS Rock Chucker Press that has been used to cam-over for over 37 years.

(Hot Rod humor) my "high lift" cam over kits.

July 28, 2010, 04:20 PM	#1
dbomb Member Join Date: November 11, 2008 Posts: 35	Cam-over hornady single stage press I have an interesting problem, I have been reloading .45 for a while. I also got some dies for my .223 and my 300 winmag. After lots of reading I want to get my headspace correct and custom to my rifle. When I try to shoulder bump the cases. My dies for the .300 win mag (redding body die) wont do it, unless I go lower than when its touching the shellholder, which I think its called cam-over. The same thing is happening with my .223, after I shoot the case would get suck in the chambe, after a few posting I was told i had to bring the FL sizing die lower ( hornady dimension FL sizing die) which it works, but when I pay close attention again is caming over to get it where I want to. So even though its working, I dont feel too comfortable cam-over every single time. I think something will eventually give. Is it OK? or do i have to get something like the redding competiion shell holders? Thanks this forum is full of good stuff, keep it up.

July 28, 2010, 08:26 PM	#5
Bill Daniel Senior Member Join Date: February 10, 2000 Location: Bowling Green, KY. Posts: 518	Cam over dbomb, the instructions for my LNL stated that the ram should be raised all the way up and the sizing die screwed down to it till it touched and then a quarter turn or so lower before locking it in place so that the press would "cam-over" at the top of the stroke. Bill Daniel __________________ Prosecute criminals to the fullest extent of the law and their weapons will become harmless. "Let us speak courteously, deal fairly, and keep ourselves armed and ready." Theodore Roosevelt 1903

July 31, 2010, 12:29 PM	#9
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	Goodness. Cam-over refers to toggle block and ram over-travel. It's the same even if no die is present unless we block the ram with a die adjustment. As the lever/toggle link pushes the ram up, they will reach the point of top-dead-center where lever pressure has had it's maximum effect. Any further lever/ram travel after TDC is "cam over" and, if it's designed for that, the ram will typically travel back down just a tad. In effect, it means nothing special. We can screw dies down in any press until they stop the ram before TDC and get exactly the same result as with other presses that have a built-in travel stop that prevents camming over. Die "instructions" saying to turn sizer dies down to contact and some additional magic 1/4 turn, etc, are great simplifications. That just makes sure noobs will get cases that will chamber in any rifle ever made in that caliber and but it certainly isn't the best way to do his FL sizing! A major (potential) advantage of handloading is to custom fit our ammo to our own weapons, I couldn't care less if my loads don't fit any others! Individual presses and dies require slightly different amounts of "extra" turning for best fit. It's up to the individual reloader to learn exactly where he needs to position his sizer to produce sized cases that shoot best and last longest. The type of press operation - cam vs. no cam - makes no difference in accomplishing that. Last edited by wncchester; July 31, 2010 at 12:38 PM.

November 5, 2010, 03:39 PM	#19
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	"...using Hornady Shellholders or are you using LEE or RCBS? The shell holders have different deck heigths " Mr. Horton is correct, the SAAMI design "deck height" of all shell holders is 1/8th inch, .125". All dies are bored to accept that depth as part of the die's chamber. In some 40+ years I've never had a need to reduce a die or shell holder but, if I did, I would change the die mouth since that's likely where the problem is. All cam-over in a press means is the toggle link has rotated passed top dead center and the ram has started back down. There is no mechanical value in cam-over vs. simply stopping at the top of the ram's travel. The mechanical advantage of a compound toggle system comes from the swinging arms moving the pivot pins closer to the line of force as the toggle rotates; that moving fulcrum principle is what vastly multiplies the compound toggle leverage compared to the older simple toggle system Last edited by wncchester; November 5, 2010 at 06:22 PM.

July 28, 2010, 04:29 PM	#2
demigod Junior member Join Date: March 13, 2008 Location: AZ Posts: 1,129	I think I have a resizing die that does that when I dry cycle my LnL single stage. I guess it depends on how heavy the cam over is. One of my dies does it slightly. Are you using a headspace guage for your rifle brass?? I set my dies up so the resized brass fits perfectly into a headspace guage. I also check the headspace guage by running known good factory ammo through it. That way I get a thorough cross check on the press and the guage.

July 28, 2010, 04:38 PM	#3
dbomb Member Join Date: November 11, 2008 Posts: 35	I use the Hornady Lock N Load Headspace Gauge Kit, for my .300 I went last weekend and shot about 20 rounds and measure them. then substraced .002. and came up with the number. 2.271" I got the gauges because after a while the bolt was hard to close and sometimes the bolt wouldn't open after firing. So i wanted to know exactly what size I needed my cases to be.

July 28, 2010, 05:36 PM	#4
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	Terms I do not use, datum, datum line, bump and cam over, I have at least 4 presses that cam over, not one of the 4 is an RCBS, all my RCBS JAM OVER, lock up and stop, . I am one of the few with gages that can measure 'cam over', if others could they would stop talking about it. I do not have a Hornady (I have a Pacific) if I did I would measure it for CAM OVER. A press that cams over does not bump, it bump-bumps as in it bumps on the way up and again when the ram reaches the top and starts back down before hitting the maximum travel, so it bumps again on the return trip down, the RCBS A-2 press is THE CAM OVER PRESS, no tools necessary, Jam over or cam over, who knows, for most it is the unknown, for years the amount of travel that is not used by the press to size the case is used to stretch, flex, deflect the press described by the term STRAIN, again I have a strain gage and a deflection gage and the dial indicator can be set up to measure deflection (and cam over), just a guess but I believe there are those that jam/cam the press over every time they size a case and have been doing it for years without harm to the press. Again I use the companion tool to the press tool the feeler gage. F. Guffey

July 28, 2010, 10:12 PM	#6
dbomb Member Join Date: November 11, 2008 Posts: 35	So i guess its OK to cam-over. I was concern that I was doing something wrong. To get the measurements that I needed to FL size my cases, and match my headspace measurement I had to cam-over the press. So Looks like I'm back at mass production

July 29, 2010, 07:18 AM	#7
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	dbomb, yes it is, it is OK to jam-up, lock-up and or put the press into a bind if it is necessary or out of habit or because the instructions say you gotta do-it, RCBS instructions say the same thing, they know better, they make the press but omit the change if directions as in up, stop and return, the RCBS ram goes up then stops, goes into a bind, the bottom of the ram kick out and the ram tilts etc. but never returns (changes directions), SO, the RCBS Rockchucker does not cam over, it goes into a bind. How tough is the case to size? Dose the case have that much resistance to sizing? Even after that cramming, jamming and crushing, flexing, deflection did the case get sized because the press is tougher than the case, or did the case win and if it did how could the reloader determine the amount of of case that did not get sized? If the case does not get sized during sizing with the 1/4 additional turn the part of the case that is not sized must be sticking out somewhere. I know, spring back, it's spring back, not on my cases, not on my presses, most of my cases have no memory of what they were when they started, 30/06 to 257 Roberts? The only memory is the reminder on the head of the case, again I check head space first, then adjust the die to size/form. I do not work a press any harder than required, I do not have a problem with sizing a case, I do want the case to fit the chamber, sometimes I am required to add .010 thousands to the length of the case from the head of the case to the shoulder, I can not do that by camming/jamming the press. F. Guffey

July 30, 2010, 09:06 PM	#8
dbomb Member Join Date: November 11, 2008 Posts: 35	No, there isn't much resistance. I follow the LNL dimension dies to set up the FL die. Then started to screw it down till I got the headspace I needed. It turned out to be 1/4 turn more, for my .223. I haven't done it to my .300 to find out how much it goes down. But again looks like its all good to go. Thanks for the all posts and advice.

July 31, 2010, 05:18 PM	#10
PA-Joe Senior Member Join Date: June 9, 2010 Location: NEPA Posts: 909	You can also remove 0.001 from the shell holders using 400 grit paper. A little at a time until your shoulders are bumped back to where you need them.

November 1, 2010, 11:31 AM	#11
demigod Junior member Join Date: March 13, 2008 Location: AZ Posts: 1,129	I recently discovered that on my LNL classic there are chunks of the lugs on the PRESS BUSHING that have broken away! I need to take a close look at all my die bushings to see if there's anything going on with them. But I have a little bit of cam over on my 9mm die when there's no brass in the press. When I'm actually resizing a piece of 9mm, the cam over isn't happening due to the resistance of the sizing die on the brass. I'm wondering if the cam over didn't damage the Press bushing.

November 1, 2010, 02:08 PM	#12
PA-Joe Senior Member Join Date: June 9, 2010 Location: NEPA Posts: 909	Just wondering if you are all using Hornady Shellholders or are you using LEE or RCBS? The shell holders have different deck heigths and that may be why you are not bumping the shoulders back enough. There was a case a few months ago where changing the shellholder corrected the problem.

November 1, 2010, 03:39 PM	#13
demigod Junior member Join Date: March 13, 2008 Location: AZ Posts: 1,129	I'm using Hornady shell holders.

November 1, 2010, 07:06 PM	#14
demigod Junior member Join Date: March 13, 2008 Location: AZ Posts: 1,129

November 5, 2010, 11:24 AM	#16
demigod Junior member Join Date: March 13, 2008 Location: AZ Posts: 1,129	Talked to Hornady today. They apparently had a vender supply them with some press bushings that have been chipping/breaking. They're sending out a replacement today!

November 5, 2010, 01:50 PM	#17
Edward Horton Junior member Join Date: October 12, 2009 Posts: 70	RCBS makes the Precision Mic for measuring your cases before and after being fired to properly set up your resizing dies. The "zero" on the gauge represents minimum "rifle" headspace. The average factory loaded ammunition is .002 smaller than minimum headspace to ensure the cartridge will chamber in any rifle. "YOUR" fired case will be longer and this is why you can neck size only and not over resize your brass and make your cases last longer. When full length resizing for "YOUR" rifle you only need to push the shoulder of the case "back" approximately .001 to chamber without any bolt resistance on closing. When partially full length resizing you can actually make the case shoulder "LONGER" than before it was fired. When full length resizing the brass case has only one direction it can move and that is "upward" and the shoulder of the case will be pushed forward. "Partial" full length resizing is used to only push the shoulder of the case back far enough to chamber in "YOUR" rifle and "NOT" over resize the case. "Cam over" or making sure the base of the full length resizing die is making firm hard contact with the shell holder makes sure the cartridge will chamber in "ANY" rifle after sizing, because you have pushed the shoulder of the case back below minimum headspace. This is why they make custom shell holders that are "LONGER" than a standard shell holder and allow you to adjust your "cartridge" headspace. Also remember to place a lubed cartridge case in the shell holder when adjusting your dies to "center" the die in the press before locking down the die lock ring.

November 5, 2010, 03:54 PM	#20
Edward Horton Junior member Join Date: October 12, 2009 Posts: 70	Happy RCBS Rock Chucker Press that has been used to cam-over for over 37 years. (Hot Rod humor) my "high lift" cam over kits.