RCBS PRecission Mic

[Yosemite Steve]

Lapping a Savage bolt head is unnecessary. The floating design allows for a perfect fit similar to a custom action or a trued Mauser or Remington

I disagree with this. My recent discovery is that all of the rounds fired through my Savage have case heads that are not square to the case itself. I found this a while back when measuring lengths... As I would turn the case it would measure longer or shorter in length by as much as .003".

Even though the new bolt head was lapped to the receiver face it was never squared up to the bore. I was just closing the bolt on some rounds with some feel still on them after sizing. If I turn the case and close the bolt I get around to a spot where there is more clearance. My receiver face or my lugs or both are not square to the center of the bore. I think that this is most likely an issue that has been the reason for the poor accuracy of this gun. When I have shot new brass it has shot better. The fired brass has been shaped to the crooked face of the bolt. The floating design only allows for a perfect fit if the receiver face is perfect. I either need to live with it or will have to have a gunsmith true up the receiver and then the lugs to correct it. Not very happy at the moment.

[cw308]

The floating bolt fact alignes the bolt face to the chamber is a good feature. As long as you can strip the bolt ,I find is the most accurate way to set the case to the length an the bullet to the lands . I have a Rem.700 completely blueprinted with a M24 5R Rock Creek match barrel .I set my case headspace to .0015 - .002 an what shoots best in my barrel is a .002 jump using a Sierra 168grn.MK over 40.8 gn.of IMR 4064 F/L sized case. I shoot only 200 yards , that's the maximum distance for the ranges in my area .5 five shot groups sometimes better, if I do my part . The rifle can shoot better then me I'm sure. I'm not as steady an eyes aren't as good anymore , but still love shooting.

[hounddawg]

if you want a better bolt face replace it with a PTG

[Yosemite Steve]

The floating bolt fact alignes to the bolt face to the chamber is a good fetcher? I can't decipher this one.

[cw308]

Yosemite Steve
Only trying to help . Sorry for the confusion . Sometimes it's better keeping my comments to myself.

[Yosemite Steve]

It's ok I just didn't undetstand what you said. Please explain.

[F. Guffey]

The floating bolt fact alignes to the bolt face to the chamber is a good fetcher? I can't decipher this one.

The floating bolt face? "the chamber is a good fetcher"? or feature.

My Rock Chucker ram jumps forward when it is raised if I do not have a case in the shell holder so I would say the case is the 'aligner'. I can not get reloaders to take their hands off of the key boards so? You will have to take my word for it. If my Rock Chucker was a cam over press it would not go into a bind when the ram reached the top of it's travel.

F. Guffey

[cw308]

A floating bolt face will square itself to the chamber . On my Rem. 700 if the bolt face wasn't true or square with the chamber , when the round is fired the case head an case body would be off center .

[Yosemite Steve]

Thanks Guffey. Now I don't know why I could not see that. I will stop throwing the stick now. My arm is tired and my bolt face just sits there.

You say that your Rock Chucker is not a cam over press. I am using one and do use the cam over method. Would you please elaborate on what you mean. Am I under the wrong impression here or do you have yours set up so it cannot cam over? Mine has an RV cam so it won't ping going up hills.

[Yosemite Steve]

A floating bolt face will square itself to the chamber . On my Rem. 700 if the bolt face wasn't true or square with the chamber , when the round is fired the case head an case body would be off center .

That was what the guy at the Sporting goods store had said when he sold us the gun. There was something familiar about the gunsmith who worked on my gun recently who I had problems with. I just found out he was the guy who sold us the gun 32 years ago. He knew about the floating bolt face yet he assembled the bolt head to the bolt in such a way that is was jammed together and one lug would not even touch. Still makes me grumpy. I think I got my lugs so they are holding the bolt face true now (as of last night) so hopefully I will be exploiting that feature in the future.

[Yosemite Steve]

Thanks cw308.

[hounddawg]

according to everyone in the reloading world a press with a eccentric linkage is a cam over press. Rock Chuckers have eccentric linkages

CAM-OVER: DON’T DO IT. JUST DON’T.

[Yosemite Steve]

CAM-OVER: DON’T DO IT. JUST DON’T.

I am in half agreement with this blog. In the case of my press the cam over puts the shell holder the the top of the travel it can reach and a bit past. I think that this is good because it assures me that I have gone to the maximum reach of the stroke, particularly when my die and shell holder are not making contact. In the instance where a reloader puts the die in contact with the shell holder I think it is still ok to let it cam over but with moderation. When the shell holder meets the die with enough pressure to fully contact the surfaces resizing is done. The cam over can be adjusted so that it does not put an egregious amount of pressure on things. Here is an instance where a precision mic would be useful in measuring how much contact is enough and how much does nothing more. The instructions for my Rock Chucker are a little "over the top" with regards to how much further to screw in the die. I think that 1/8 turn past contact is enough to cam over but not enough to wear things out.

[cw308]

I also size with the Rock Chucker , I screw the die down to the shellholder not to cam over but to remove any slack in the threads . I full length size my brass and never had to cam over or would want to , Once the die bottoms out on the shellholder what good is a cam over doing ? It would seem to me only harming the press or am I missing something ? It is the same with the PM as it screws down to the shoulder or the bullet ogive , you can feel the contact point . With cam over for some reason the case can not be sized down enough, better to have a custom die made . I'm lucky I guess , never had that problem.

[hounddawg]

Once the die bottoms out on the shellholder what good is a cam over doing ? It would seem to me only harming the press or am I missing something ?

I think you are dead on. That shell holder ain't gonna get any thinner. No need to stress the press

[F. Guffey]

You say that your Rock Chucker is not a cam over press. I am using one and do use the cam over method.

I have 12 Herter presses, all of my Herter presses are cam over presses. Again, there are two members on this forum that have instructions for presses from RCBS. One of their last cam over presses was the A2. RCBS identified the press as a cam over press and they identified the A2 as a bump press because it was a cam over press.

And then one day a reloader walked into a Cabela's store with a video camera and starting videoing the ram going up and down while he was operating the handle on a Rock Chucker. He then decided the press was made in China because the ram came to the top and then kicked forward. The press did not have a die, shell holder or case installed. And then the bashing started; I tried to get ahead of it by explaining I have (at the time) 4 Rock Chuckers and all 4 had this problem of locking up, jamming up and getting tangled when the ram came up with no case in the shell holder.

I could not get a reloader to crawl under the table to examine the linkage, I could not get a reloader to push himself away from the keyboard long enough to stand up and look thorough the hole in the top of the Rock Chucker to determine if the ram kicked forward or if it cam-ed over. I could not get anyone to do the research but there is a company that makes Vise grip plyers. In one of their patents they claim they invented 'the leaver lock'.

I can measure the amount of cam over in thousandths on all of my cam over presses. The last A2 I operated had .017", in my opinion that is too much.

I have never been able to get the ram on the Rock Chucker to change directions with one exception. I modified one Rock Chucker by grinding the contact points between the toggle and linkage. I do not have to worry about that happening again because a reloader would have to get up and look under the table to find the toggle.

I believe they should take Red Green's advise, reloaders have a choice; they can be handy or they can be cute.

F. Guffey

[cw308]

F.G
I always enjoy reading your posts . And sometimes I find myself saying What an starring at the wall.Thanks again ..

Chris

[hounddawg]

Just Looked at the linkage on my RCBS Rockchucker and when I raise the ram the linkage first moves back then forwards in an elliptical motion. The ram itself is bushed so that it moves only vertically. If that ram starts moving in the x and z planes I would think it is time to rebush it and if that isn't a cam over press I just think I will be wrong with the rest of the world

We used to have a saying in the Navy...there is a right way, a wrong way and the Navy way. I think that could be adapted to this forum

[F. Guffey]

The ram itself is bushed so that it moves only vertically.

RCBS will give you another press before they would install bushings. I would knurl the hole through the press before I would exchange one of my presses. RCBS sent me a new ram with the instillation kit.

And one more time, I have never seen a Rock Chucker that cams over, I know a lot of reloaders that believe their Rock Chucker cams over and they believe their cam over presses bump. If it bumps it has to do it twice, once on the way up and again on the way down. The two reloaders that have RCBS press instructions know the cam over press is adjusted differently than the non cam over press.

Again: The Rock Chucker is aligned with a case, if there is no case in the shell holder the ram is kicked back at the bottom and forward at the die,, it is nothing personal, that is the way it is.

F. Guffey

[Unclenick]

Mr. Guffey is correct. Camming over does not depend on the linkage type or the shape of its travel path. I think elliptical cam lobes on crankshafts are confusing people trying to define camming over by the shape of the motion. But as the dictionary says, even a cylinder turning on a shaft eccentrically (round, not elliptical cross-section) can impart linear motion to a connecting rod in a machine, so it is also called a cam.

In the case of a press, all camming-over depends on is the handle having enough range of movement to drive the press ram to the top of the stroke (camming up) and past the top of the stroke to start dropping the ram back down again (camming down). The transition from camming up over to camming down is called camming-over. This transition happens when the maximum extreme position of the linearly moving part (the ram) is reached and passed without reversing the motion of the handle. This is analogous, but upside-down from a valve cam turning past the point the valve is maximally depressed and starting to let it come back up again. That is camming over from linear motion of the valve stem in one direction to linear motion in the other direction.

The reason camming-over matters, whether the linkage is compound or a simple pivoting handle design, is that either mechanism approaches theoretical (in an ideal, infinitely rigid, zero friction machine) infinite mechanical advantage as the ram passes through the top of the linear ram stroke. That much mechanical advantage can break the press, damage tooling, etc. That's the reason to avoid it.

Most presses these days have overtravel stops to halt the handle just before mechanical advantage gets dangerously high. Usually, it works to protect the equipment, though we had one fellow on another forum, who was an admittedly ham-handed linebacker size fellow, who broke two Rockchucker castings trying to turn his resizing die in further and further because it wasn't making his cases as short as he wanted it. Sometimes the Armstrong method is not best.

[hounddawg]

The Rock Chucker is aligned with a case, if there is no case in the shell holder the ram is kicked back at the bottom and forward at the die,, it is nothing personal, that is the way it is.

been working on equipment going on 50 years now and pretty sure my ram is goes nowhere except up and down. no forward backward or lateral movement

but so be it, I am not sit here and argue semantics, this forum is growing tedious

[Yosemite Steve]

I think I understand now. I think that Hounddawg and I have the same rig.
Whatever the definition is, I have a 40 year old Rock Chucker Part #14881 and in the instructions for the dies it says:

Screw the Full Length or Neck Sizer Die into the Press until the Die touches the Shell Holder when the Shell Holder is brought up to the top of the press stroke. Be sure all play is removed from the press leverage system. To do this, adjust the Die as above, lower the Shell Holder and set the Die 1/8" to 1/4" turn further down so the press cams over center. Set the large lock ring.

I even used all the capital letters like the instructions. As I wrote this I thought of something. I misunderstood the instructions to say 1/8 to 1/4 turn further down. It says 1/8" to 1/4" turn... Ooops. :P

There is no stop on my linkage system so it most certainly does cam over. The ram goes up and then down just a bit at the end of the stroke of the handle. It then goes back up again and then down all the way as the handle is brought back up. I think that as long as the die is not turned too far down this is a good way to regulate the contact pressure on the die or the travel of the ram is the case such as mine where I do not touch the die at all. I agree that too much will most certainly be wear on the press. The fact that there is no stop for my handle allows the ram to go to it's top and then back down a tad at the end of the stroke. For me to build a stop would require some very hard and thick steel that would not give in relation to my press. It cams over. Yes it does!


Mine does as Guffey said in that with it not having a case to guide it, at the top of the stroke it moves laterally about .010".

[F. Guffey]

Mine does as Guffey said in that with it not having a case to guide it, at the top of the stroke it moves laterally about .010".

And if I could get a reloader to crawl under the press and watch all of the parts move I believe a few of them could find the stop. The toggle hits the linkage when that happens the ram has no other way to go but back, to cam over the linkage would have to change directions. And then there is 'by how much? If my Rock Chuckers were cam over presses I could measure the amount of cam over; my rock Chuckers go into a bind, lock up, jam up etc.

been working on equipment going on 50 years now and pretty sure my ram is goes nowhere except up and down.

And now we are back to the floating bolt face; the face of the bolt does not align the case, the case aligns the floating bolt face. Again, years ago I removed metal from the stops on a Rock Chucker, after removing metal from the two contact points travel was increased and the jam up, lock up no longer kecked the ram back at the bottom

I have no trouble accepting the fact my ram is kicked back at the bottom and forward at the top. It does seem to me anyone that has been working on equipment for 50 years would realize that is a good way to create an hour glass looking hole in the press.

F. Guffey

[Yosemite Steve]

Guffey, my press handle stops when it hits the wood it is mounted to or it would go further. It has never jammed. I understand what you were saying about the bolt face. Yes it is aligned by the case. But the bolt face was not square to the bore when seated agaist the reciever so the heads of my cases were also not square to the bore after firing. I resolved that problem by filing down the high lug. I now have .0005" more space from my bolt face to datum/shoulder.

[hounddawg]

Guffy I believe you are mistaking slop in the linkage to thinking it is the ram moving laterally. Using a quality dial indicator and magnetic base I just measured the lateral movement of my ram and it measured at a Class III medium fit tolerance as per ANSI 4.1. Less than .0027

I do agree with your assessment of the floating bolt head however