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Question about Rock chucker.
- Thread starter Chainsaw.
- Start date
If pistol brass, just stop when the ram/shell-holder contact the die.
If rifle brass (and full sizing as I would recommend to start out),
just the slightest cam-over when sizing an actual lubed* case.
*Make sure that you use a good lube like Lee/RCBS. A little goes a long
way w/ these, but makes all the difference in how much force is involved.
If rifle brass (and full sizing as I would recommend to start out),
just the slightest cam-over when sizing an actual lubed* case.
*Make sure that you use a good lube like Lee/RCBS. A little goes a long
way w/ these, but makes all the difference in how much force is involved.
USMC 77-81
New member
Don't cam over on a carbide die, you'll damage/destroy it. On steel sizer dies run the ram to the top of the stroke, screw the die down until it contacts the shell holder, lower the ram and screw the die down another 1/8 to 1/4 of a turn to get the cam over effect.
Personally I only adjust for cam over when F.L. sizing rifle brass for the first time, after shooting in my gun(s), which fire forms the case to the chamber, I then only adjust the die to contact the shell holder, minimizing the working of the brass.
Also, call RCBS, they'll send you the literature for your press.
As for lube, very little is needed, if you are seeing dents on the shoulder, which is called Hydraulic denting, you are using to much. I only lube every other case and then gently wipe with a rag prior to running it through the die. Be sure to just touch the case mouth with lube also to prevent the neck from galling.
1st Marine division, 3rd Marines
Personally I only adjust for cam over when F.L. sizing rifle brass for the first time, after shooting in my gun(s), which fire forms the case to the chamber, I then only adjust the die to contact the shell holder, minimizing the working of the brass.
Also, call RCBS, they'll send you the literature for your press.
As for lube, very little is needed, if you are seeing dents on the shoulder, which is called Hydraulic denting, you are using to much. I only lube every other case and then gently wipe with a rag prior to running it through the die. Be sure to just touch the case mouth with lube also to prevent the neck from galling.
1st Marine division, 3rd Marines
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Just got a new one, my first. My question is should I be (on sizing) having the case holder stop the stroke on the dye before the handle cams over into the stops or should I be camming the handle over into the stops normally?
Chainsaw, good question, I like the part about the handles camming over. I have at least 3 Rock Chuckers, not one of the 3+ will cam over. My Rock Chuckers jam-up, lock-up or cram-up, the one thing they will not do is cam over. My dies have threads, all of my presses have threads, and threads make it possible to adjust my die to, off or below contact with the shell holder for a reason. Cases have the ability to resist sizing. As the case’s ability to resist sizing increases it is necessary to increase the presses ability to overcome the resistance. I find for most cases any lube will do. Then there are other time, for the other times I use a no-name lube; a very good lube can reduce the case’s ability to resist sizing.
A member notified RCBS I said the Rock Chucker did not cam over. Someone at RCBS instructed him to have me contact them etc.. Back to my Rock Chuckers, my Rock Chuckers lock up or they go into a bind or the linkage gets tangled: problem: I can not get a reloader away from the key board long enough to crawl under the bench to check.
When the Rock Chucker ram is raised the linkage limits the travel. When that happens the linkage forces the ram back at the bottom and forward at the top. All of that can be checked without a die and case installed in the press. Meaning? The case prevents the ram from being kicked back at the bottom and forward at the top.
I have gages and deflection gages, when a case has more resistance to sizing than the press can overcome the top of the press yields. Meaning if a die is adjusted with an additional fraction of a turn below contact the die should be contacting the shell holder when the ram is raised. If the case has more resistance to sizing than the press can overcome there will be a gap between the top of the shell holder and bottom of the die.
When the case whips the press I want to know by how much. When determining by how much I measure the gap between the top of the shell holder and bottom of the die with a feeler gage. In the perfect world and assuming the press won there will be no gap, on the other hand if there is a gap I have choices. I can bet a better lube of I can screw the die down an additional fraction of a turn.
F. Guffey
I have instructions from RCBS, my instructions from RCBS go back 55 years. Back then they knew the difference between a cam over and a non cam over press. My cam over presses has less ability to overcome resistance to sizing when the press is cammed over. Then there is bump like reloaders like to say they bump the shoulder back .002”. In the big inning the cam over press was referred to as being a bump press.
Back to your Rock Chucker; if your Rock Chucker was a cam over press you could adjust the die to size without bumping or you could adjust the press to bump, Not a problem but when adjusted to bump the ram bumps twice, once on the way up and again on the way down.
Then there is the companion tool to the press, the feeler gage, I use the feeler gage to verify.
F. Guffey
Back to your Rock Chucker; if your Rock Chucker was a cam over press you could adjust the die to size without bumping or you could adjust the press to bump, Not a problem but when adjusted to bump the ram bumps twice, once on the way up and again on the way down.
Then there is the companion tool to the press, the feeler gage, I use the feeler gage to verify.
F. Guffey
I believe that both the press and your dies will have directions as to the perfect setup of your equipment. I would follow those,
FITASC, I wouldn’t, there is no logic to mindlessly sizing cases for a chamber he does not have. My presses have threads, my dies have threads. Threads make my dies adjustable. Instructions will get the OP to the point he can return the case to minimum length/full length sized. Then there is that part about the case having more resistance to sizing than the press, die and lube can overcome.
Then there is that other part about instructions, measure before and again after. That would be before firing and again after firing. After firing there is sizing. And then I always like to add that part the instructions omit. The chamber can be go-gage length from the shoulder to the bolt face. The chamber can be no go-gage length and it can be field reject length. With one exception, I measure the length of the chamber in thousandths. That is 11 different lengths between go-gage and field reject length.
F. Guffey
Use consistent case lube. Some dies require firm contact with the shellholder to get enough shoulder push back. Others may oversize the shoulder with firm contact. Some tight chambered bolt actions may require firm contact while AR style chambers would be oversized with firm contact. Brass that is softer or new may resize differently than harder, thicker, or multi-fired. Best to get a case Headspace Gauge so you can accurately measure the fired cases and set your sizing die to push the shoulders back a measured amount. Carbide pistol dies can be cracked and ruined with firm contact with the shellholder. I don't like cam over as I just think it is hard on a press linkage?? Depends on your dies manufacturing dimensions and shellholder dimensions as to how much your case is sized and the only way to KNOW is a case headspace gauge. I like Hornady's Headspace gauge set which works with your calipers and the set will measure most all rifle cases. The RCBS Precision Mic is another good gauge.
Haha, first cam-over on a Rockchucker and now someone just mentioned case headspace. F.Guffey's keyboard is about to get a workout.
Isn’t that the truth, my cases do not have head space and my Wilson cases gages are not head space gages. Understand my Wilson case gages are old, so old they were manufactured before the Internet. After the Internet every tool became a head space gage and everything has head space. Manufacturers learned to add the word ‘head space’ to the name of a tool, they knew reloaders would type head space into Google search.
I was ask by one manufacturer if I would agree with him. He said he thought the reloading industry would benefit. I responded with a ‘big Cajun no’.
F. Guffey
Chainsaw, good choice. I've been using the RCBS Rockchucker for over 25 years, great press. Setting as per the instructions, raise the ram all the way , screw the die until it makes contact with the shell holder, this removes any slack in the threads. And yes this may be oversizing your brass. Now we're talking headspace, Do you know what that is and how to check for it.?
The reason rcbs instructs you to set your sizing die to a depth that causes your press to "slightly overcam" is so the average novice handloader that has no means to precisely measure headspace can obtain a close headspace . Setting your ram for a overcam is a "somewhat" reasonably close reference to achieve needed headspace clearance. I've since graduated from novice to amatuer case sizer as now I use a digital headspace gauge to achieve correct and consistent repeatable sized casings. I also find that setting the rock chucker for the slight overcam is in reality pretty darn close to a sammi spec new unfired casing.
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