Help me understand die set up

[KenOath]

Ok... I just set up my 3rd Harrell's die, this latest one is for a 6BRA. Instructions are as per normal, raise press ram with appropriate shell holder to top of its stroke, then screw die down till it bottoms out on shell holder, then I screw my PMA micro adjuster down till it bottoms out on top of press then lock it of. I measure a fired piece of brass to get a measurement to set shoulder back .0015" ish, I then run brass into press as set up and no movement which is normal, I turn die into press .0025" more to get my .0015" set back on shoulder, the .200" line and shoulder junction size fine to with a slight overcam on press handle , round cambers with no resistance... What I don't understand is if the die is hard against shell holder how can screwing die into press give more movement when you already have steel on steel??

Cheers Rushty

 

[Clancy]

I'm not one to question things that work. If they work, great, I don't need an explanation.

Best guesses are play in the ram and time the case spends under compression.

You'd be better off shaving your shellholder though if it feels hard to cam over.

 

[BoydAllen]

Years back, I set a .220 Swift FL die so that without a sized case in the shell holder the die was touching the shell holder, all of this in my Rock Chucker press. I lubed a case, put it in the shell holder and raised the ram to its highest position and noticed that there was now a gap between the die and the shell holder. Curious about how big it was I got out my set of automotive feeler gauges and found the one that had the best fit. It was .006 thick. Which means that I had another .006 to play with for die adjustment, if I needed it. This was with a cast Iron O press. I would guess that something similar is happening with your setup. In the case of the Rock Chucker it was probably linkage stretch. Other designs and materials might react differently to the stress of sizing.

 

[ireload2]

Your press frame will yield about .002 under the heavy load of FL resizing.
I have measured that much stretch with a 1971 Rockchucker.

Ok... I just set up my 3rd Harrell's die, this latest one is for a 6BRA. Instructions are as per normal, raise press ram with appropriate shell holder to top of its stroke, then screw die down till it bottoms out on shell holder, then I screw my PMA micro adjuster down till it bottoms out on top of press then lock it of. I measure a fired piece of brass to get a measurement to set shoulder back .0015" ish, I then run brass into press as set up and no movement which is normal, I turn die into press .0025" more to get my .0015" set back on shoulder, the .200" line and shoulder junction size fine to with a slight overcam on press handle , round cambers with no resistance... What I don't understand is if the die is hard against shell holder how can screwing die into press give more movement when you already have steel on steel??

Cheers Rushty

 

[Texas10]

When I set up a 22-250 with an X-caliber barrel, I thought I had set the headspace fairly close using a new piece of Lapua brass. Then I ran into the same issue you describe with die set up. So I put the barreled action back into the vice, loosened the barrel nut and tightened up the headspace just a bit more. Problem solved, dies have enough adjustment room and very little growth in brass.

 

[Shynloco]

Rushty,
FWIW, when I setup any die in my press (2 Harrells and a Redding Big Boss) I've learned to screw the die in to touch the shell holder AND THEN back off at least a quarter of a turn. As Boyd said, that gives me room to play with for sizing the brass to get the exact bump I need for that brass. I'm not a big fan of having to "camover" as you've left little "wiggle room" for small adjustment if needed.

Alex

 

[BoydAllen]

I always start die set up with the die backed off. If I have a problem getting to the bump that I want with a barrel that has a shoulder (not a barrel nut) I generally will cut down the shell holder a few thousandths. Shell holders are cheap and softer than dies and easier to work on. For me, setting a die is no big deal, but I have observed that some tend to view it as something that is a major operation that once done does not have to be revisited. If you are setting your bump as close as I do, and reusing a small set of cases, work hardening will require that you reset your die to maintain bump. I use a set of cases in rotation so that they harden at about the same rate, and check my bump every time that I size them.

 

[ireload2]

A good start is to run the die down against the shell holder then turn down about 1/10 of a turn.
Remove the expander and FL size the case 6 or 8 times. Turn the case about 1/4 turn to 1/3 turn before each sizing stroke. Let the case dwell about 4 seconds at the top of each stroke. When finished you can measure the many times sized case with a Hornady tool and you will know the smallest possible case length you die will produce.
Then measure a fired case from your rifle and measure it. You can easily tell how far down to set your die to get .000 to .001 shoulder bump. Mark the length on the many times sized case and store it with your dies.

 

[kvd]

Unless one is willing to mitigate one of the good design features of the Forster Co-Ax press – namely the built in universal shell holder, then the practice of removing a few thousandths of an inch of material from the shell holder to achieve the desired shoulder bump is not an option. Fortunately for its users, the Co-Ax press will cam over big time – to the point where cases actually need to be fire formed again because of excessive shoulder pushback if one is not paying attention. Just continue screwing the die in until the desired shoulder bump is measured with no fear of ruining anything. Like the OP, one wonders how more downward adjustment can yield any more sizing once the die touches the shell holder (or shell plate in the case of the Co-Ax) but is does. Forster recommends using their aluminum die rings. Perhaps there is enough give in the aluminum rings and their threads when slid into the slot for them in the press that plenty of adjustment is available beyond what appears to be the maximum downward adjustment.

My 2¢ worth

Ken

 

[6MMsteve]

When I set up a 22-250 with an X-caliber barrel, I thought I had set the headspace fairly close using a new piece of Lapua brass. Then I ran into the same issue you describe with die set up. So I put the barreled action back into the vice, loosened the barrel nut and tightened up the headspace just a bit more. Problem solved, dies have enough adjustment room and very little growth in brass.

that's how I setup my savages usually 2x fire a few then reheadspace and reset dies, just how I do it, not smart enough I guess

 

[kvd]

Turn the case about 1/4 turn to 1/3 turn before each sizing stroke. Let the case dwell about 4 seconds at the top of each stroke.

This is good advice.

Most freshman Engineering students at some point are shown the example of strain rate utilizing the child’s toy Silly Putty. If one grabs it with both hands and yanks it, the silly putty will break into two pieces. On the other hand, if it is slowly pulled apart, it will stretch and sag and will not break. On a much less visible scale, this is what cartridge brass will do. If the strain rate is high, as in rapidly running the case into the die and pulling it out, the case will deform and spring back. However, if the sizing is done slowly, with a dwell at full stroke, the strain rate will be low and the brass will retain the desired shape.

Ken

 

[6MMsteve]

This is good advice.

Most freshman Engineering students at some point are shown the example of strain rate utilizing the child’s toy Silly Putty. If one grabs it with both hands and yanks it, the silly putty will break into two pieces. On the other hand, if it is slowly pulled apart, it will stretch and sag and will not break. On a much less visible scale, this is what cartridge brass will do. If the strain rate is high, as in rapidly running the case into the die and pulling it out, the case will deform and spring back. However, if the sizing is done slowly, with a dwell at full stroke, the strain rate will be low and the brass will retain the desired shape.

Ken

how long a dwell 3or4 seconds

 

[kvd]

how long a dwell 3or4 seconds

No set time really - just not a fast ram in and out. I run the case in slowly, pause for 3 to 5 seconds, drop the ram, turn the case approximately a quarter turn and repeat.

Ken

 

[slydo]

Ok... I just set up my 3rd Harrell's die, this latest one is for a 6BRA. Instructions are as per normal, raise press ram with appropriate shell holder to top of its stroke, then screw die down till it bottoms out on shell holder, then I screw my PMA micro adjuster down till it bottoms out on top of press then lock it of. I measure a fired piece of brass to get a measurement to set shoulder back .0015" ish, I then run brass into press as set up and no movement which is normal, I turn die into press .0025" more to get my .0015" set back on shoulder, the .200" line and shoulder junction size fine to with a slight overcam on press handle , round cambers with no resistance... What I don't understand is if the die is hard against shell holder how can screwing die into press give more movement when you already have steel on steel??

Cheers Rushty

Had kind of same problems...
Shell holder...they are NOT the same thickness...
Have 3 Lee #5
From where it's sit on the ram to where the shell sits... .112" - .122" - .132"
Only the .132" works for me
Check if you can insert a filler gauge between the shell holder and the case when the ram is cycle all in
Good luck

 

[fkimble@charter.net]

Bottom of shell holder to where case sits is irrelevent. It's where case sits in shell holder to top of shell holder that limits case bump and can limit sizing at the .200 line.

Frank

 

[SeabeeKen]

I always felt like the shellholder had some vertical give in its mounting but it could be as Boyd says and in the linkage. Another reason I like Reddings competition shellholder system. Saves me a bit of die adjusting.

 

[JMayo]

I hope the op figured it out since 2017 !

I don't give one care about "setting up according to instructions". Screw it in until desired shoulder is snuck up on and then stop.
Figuring out the middle zone in a pma tool is a bigger issue to me !

 

[Webster]

Ok... I just set up my 3rd Harrell's die, this latest one is for a 6BRA. Instructions are as per normal, raise press ram with appropriate shell holder to top of its stroke, then screw die down till it bottoms out on shell holder, then I screw my PMA micro adjuster down till it bottoms out on top of press then lock it of. I measure a fired piece of brass to get a measurement to set shoulder back .0015" ish, I then run brass into press as set up and no movement which is normal, I turn die into press .0025" more to get my .0015" set back on shoulder, the .200" line and shoulder junction size fine to with a slight overcam on press handle , round cambers with no resistance... What I don't understand is if the die is hard against shell holder how can screwing die into press give more movement when you already have steel on steel??

Cheers Rushty

A lot of tolerances to stack up. I never had an adjustment wear the die touched the shell holder and it needed a little more down turn. I would forget about all the up and down on the die. Sounds like you get the bump you want. Cartridges load easily. Sounds like the adjustment you ended up with works fine. Don’t worry about it.

I also had thoughts about camming over pushing the case farther into the die when you have die to shell holder contact. I have trouble related this to press spring back. Metal to metal contact. Pushing any farther into the die is magic. I cam over a little when I size to get 0.002" bump. I only cam over because it's a positive stop to the lever.