• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

Die Shims or competition shell holders?

Contrary to popular belief:rolleyes: fguffey is pretty sharp. Dies are set to work at the top of the ram's travel. "Cam over" not only makes it more difficult to properly set the depth of the die, but then on the downstroke, the last little bit of the action is repeated as the ram first lifts, then goes down again. Once that ram reaches the top of it's stroke, it isn't going any further, no matter how hard you pull that handle. If you are trying to achieve precision case length, forget about the "cam over". Other than the feel-good thing, or trying to flex the press, and adding additional cost to the manufacturing process, what exactly does "cam over" accomplish?
 
Last edited:
Press linkage parts can stretch under the stress of sizing cases Within a given set of cases, all fired in the same chamber, at similar pressures, cases that have more lube stress the linkage less, it stretches less, and shoulder bump will vary accordingly. This will also vary with the construction of cases, from brand to brand and caliber to caliber. Some cases have relatively thin shoulders, while others' shoulders are much more resistant to being pushed back, because of material differences, thickness differences, and shoulder angle and diameter. Competition shell holder sets do not come shorter than standard ( which is sometimes what is needed). They are standard and progressively taller, in increments of .002. Another thing that will vary bump is dwell time at maximum ram extension. If you leave a case fully inserted into a die for more time and compare its bump to one that was simply stoked up and down in one motion, it will be a little shorter. The same holds true when expanding necks with a mandrel. Inconsistency in factory case annealing is also a major contributor to variance in bump. I have annealed (less than a full soft anneal) to solve this problem. We were able to retain neck tension at a suitable level for field use from a magazine, while considerably improving shoulder bump consistency. Anyone who tells you to set your dies so that the press toggles is very likely doing you a disservice because for most factory rifles this will result in shoulders that are bumped back too far, leading to incipient separation, and if continued full head separation. Finally, before I bump back from the dimension of a once fired case, I will set the die to a head to shoulder setting that is identical to the fired case (measured with the primer removed). Because cases usually take more than one firing to become tight shoulder to head, that setting will usually result sufficient clearance as long as the body of the case has been reduced in diameter. If you set your die to bump shoulders a small amount (as you should for bolt action applications) using fresh brass, after that brass has been fired and sized a number of times, in order to maintain the same bump, your die will have to be adjusted very slightly. Some time back, for Lapua cases that had been made into 6PPC, the difference was about .0025", when I accidentally size a few fresh cases using a die set for old, much used brass.
 
fguffey said:
Alignment? And for years and years I have said the ram kick back at the bottom and forward at the top and Internet reloaders are too lazy to push away from the keyboard etc. Alignment? A reloader was putting a Rock Chucker through its paces and complaing about the ram kicking forward at the top with no clue. No clue? The ram is one solid piece, if the ram kicks forward at the top the bottom of the ram kicks back at the bottom.

Again, I have 3 Rock Chuckers, all of them kick forward at the top and back at the bottom 'ONLY!'

F. Guffey
Click to expand...


I know I probably shouldn't ask this but I don't have any Rock Chuckers so I can't see for myself.

What direction is "forward" and what direction is "back", relative to a press?
 
SheepDog said:
My Rock Chucker press goes over center on the top of its stroke, isn't that "camming over"?
Click to expand...

Sheepdog, no, the ram does not go to the top, stop and then change directions. The linkage jams up and pushes the ram to the rear at the bottom. All a reloader has to do to understand this is to back away from the key board and then crawl under the bench and watch the Rock Chucker in operation. There are reloaders that claim they have precision tools, some even claim they have read the instructions, some have typed out miles and miles of gigs covering run-put; problem, not one of them has ever figured a way to measure the amount of cam over with a dial indicator. I do not want a dial indicator setting on top of my RCBS ram when it goes to the top because I am the only reloader that knows there is a good chance I could render a dial indicator scrap because; before the ram stops and then changes directions, it kicks forward at the top because of the linkage at the bottom of the press goes into a lock up bind and kicks the ram back at the bottom. I know I have been reported to RCBS as being the one that claims the Rock Chucker does not cam over. In the beginning RCBS claimed the Rock Chucker was not a cam over press, I still have instructions for RCBS presses, and then there is all of that confusions about 'bump'. In the old days a cam over press was described as a 'bump' press because it bumped once on the way up and again 'once' on the way down. And now? We have reloaders that are so good at 'it' they can bump the shoulder back .002" and I say it is impossible to move the shoulder back or bump the should back with a die that has bull length case body support.

And then? In the 1930s a company made pliers, they patented them as being leaver lock pliers. Very early in my life I had the opportunity to work in the oil field, I had a friend that had to have a plate installed, seems he was using some equipment that was leaver lock, the leaver should have been tied off with a chain loop but wasn't. When the leaver came loose it shattered his skull.

F. Guffey
 
There is NOT one single reference to a "bump press" in the 50 years of "Handloader Magazines" that I own.
What do pliers have to do with bump presses or the fact that you are the only one here that cannot bump his shoulders back?

In addition to bumping shoulders back, I also push them back, shove them back, mash them back and relocate using 7/8-14 thread dies in a no bump press. Ironic huh?

fguffey said:
Sheepdog, no, the ram does not go to the top, stop and then change directions. The linkage jams up and pushes the ram to the rear at the bottom. All a reloader has to do to understand this is to back away from the key board and then crawl under the bench and watch the Rock Chucker in operation. There are reloaders that claim they have precision tools, some even claim they have read the instructions, some have typed out miles and miles of gigs covering run-put; problem, not one of them has ever figured a way to measure the amount of cam over with a dial indicator. I do not want a dial indicator setting on top of my RCBS ram when it goes to the top because I am the only reloader that knows there is a good chance I could render a dial indicator scrap because; before the ram stops and then changes directions, it kicks forward at the top because of the linkage at the bottom of the press goes into a lock up bind and kicks the ram back at the bottom. I know I have been reported to RCBS as being the one that claims the Rock Chucker does not cam over. In the beginning RCBS claimed the Rock Chucker was not a cam over press, I still have instructions for RCBS presses, and then there is all of that confusions about 'bump'. In the old days a cam over press was described as a 'bump' press because it bumped once on the way up and again 'once' on the way down. And now? We have reloaders that are so good at 'it' they can bump the shoulder back .002" and I say it is impossible to move the shoulder back or bump the should back with a die that has bull length case body support.

And then? In the 1930s a company made pliers, they patented them as being leaver lock pliers. Very early in my life I had the opportunity to work in the oil field, I had a friend that had to have a plate installed, seems he was using some equipment that was leaver lock, the leaver should have been tied off with a chain loop but wasn't. When the leaver came loose it shattered his skull.

F. Guffey
Click to expand...
 
Last edited:
fguffey said:
Alignment? And for years and years I have said the ram kick back at the bottom and forward at the top and Internet reloaders are too lazy to push away from the keyboard etc. Alignment? A reloader was putting a Rock Chucker through its paces and complaing about the ram kicking forward at the top with no clue. No clue? The ram is one solid piece, if the ram kicks forward at the top the bottom of the ram kicks back at the bottom.

Again, I have 3 Rock Chuckers, all of them kick forward at the top and back at the bottom 'ONLY!'

F. Guffey
Click to expand...

/VH said:
I know I probably shouldn't ask this but I don't have any Rock Chuckers so I can't see for myself.

What direction is "forward" and what direction is "back", relative to a press?
Click to expand...

And then there's the part about no reloaders can answer the question. Then there's the part about the other question that probably no reloaders can answer: Does the clearance within the shellholder, between it and the case, along with the clearance between the ram and the shellholder, compensate for the "ram kicking"?

Then another question for the reloader. When the ram kicks forward at the top and back at the bottom, does it kick into alignment or out of alignment? Or, is it virtually always out of alignment, if the reloader considers alignment tolerances, for centered and parallel with the die bore, to be 0.0000000" +/- 0"?
 
Last edited:
I really dont care what Fed thinks the press does. I have loaded lots of match rounds with the press camming and maybe it goes in and out twice. All that matters to ,e is the rounds are straight and the shoulder bump is the same as measured on every round. I believe the play in the shellholders takes it out of play. Matt
 
shell holders.png
I find the graduated shell holders useful, but some care needs to be taken in their use. First, the dimension "A" is not well controlled, at least in the three sets I own. The dimensions above are for my ppc shell holders. One cannot simply change shell holders and expect case length to respond linearly. One needs to re-adjust the die-to-ram interference for each shell holder in the set. Second, as pointed out above, all presses deform elastically under load. How the die is inserted in the press - how much interference - will also change the head to shoulder dimension in the cases, so there is another adjustment in addition to the selection of the shell holder. So one can adjust finer than 0.002 by judiciously setting the interference with the die at the top of the stroke.

And, of course, each case and lubrication will produce a different spring in the press, be it ever so slight, and result in a different head to shoulder dimension even if the set-up is the same. And then there is the variation in yield strength of the case.

So, there's trial-and-error involved, and one must accept there will be length variations in cases which must be considered insetting a target length for the sizing process.
 
You must log in or register to reply here.

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Classified Ads

Forum statistics

Threads
165,833
Messages
2,204,150
Members
79,148
Latest member
tsteinmetz

Share This Page

Back
Top