Lee collet die, neck sizing without decapping mandrel?

R

RonR

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Hi All,

To get a .002 neck tension I removed the mandrel from the collet die as a test to achieve the targeted diameter. Before I continue on sizing a bunch more I would like to hear from others using the lee collet die if this acceptable practice? Hunting application.

It appears that the mandrel diameter is preventing any further reduction in inner neck dia.

(I read on one of the threads about removing the mandrel to make adjustments to neck tension for pulled loaded rounds, keeping the primer seated, but that was to resolve the issue. In this situation I would like to continue on as standard practice to not use the mandrel.)

To note
- neck turned federal brass to .011 neck thickness << calculated with bullet fit in the neck ( I realize suggested is .012 thk)
- 7mm-08
- Sierra pro hunter 140 and Sierra Game King HPBT measuring .2825 according to my calipers. Nosler BT's and Hornady SST's measuring .282
- no micrometer, noted as a more accurate method of measurement...
- sophomore reloader
- preferred to not order a .001 reduced dia mandrel if not required

Regards and as always appreciate your time.
Ron
 
I usually do this (reduce slightly) with all my Lee mandrels/expanders. They come a little rough to begin with so a quick chuck in the drill with some honing compound, then polishing paste and good to go. Takes about 5 minutes.
 
Just ran some brass through my unmodified die/mandrel.Rem brass.

Your neck thickness likely won't allow you to hit that 0.002" interference.

I got 0.0015" interference with a 0.012" wall thickness(turned)

I was however able to get another half thou or so by turning the die in a half turn and putting a heavy hand into the press , well, pretty heavy actually.

May have to look at that smaller mandrel.

I prefer factory machining to back yard stuff but a polish may get you where you need.
 
without a mandrel the diameter will be dependent on the die sizer and neck wall thickness, if you have the thickness smaller by 0.001 the inside diameter will change by 0.002, the whole idea of the mandrel is using the sizer reduce the diameter by less than required and stretch with the mandrel to size, this method allows for different wall thicknesses and keeps the inside diameter constant,
 
Hitzy said:
I usually do this (reduce slightly) with all my Lee mandrels/expanders. They come a little rough to begin with so a quick chuck in the drill with some honing compound, then polishing paste and good to go. Takes about 5 minutes.
Click to expand...

Your right...it isn't that much to remove to get that little extra. My neighbor is a ticketed machinist, probably got compounds in his garage or willing to do this for a beverage. I lapped ceramic components when I was 19 between terms at tech school...I may tackle this myself.;)

One question...if I reduce the diameter of the mandrel in order to get a .002 neck tension with .011 neck thk brass...I should still be able to adjust the die back as needed for .012 neck thk brass? ( I got to .011 with my federal brass, cutting my teeth, so to speak with neck turning. My son's PRVI brass is at .012.)


Thanks Hitzy for weighing in.

Regards
Ron
 
Kelly Timoffee said:
Your neck thickness likely won't allow you to hit that 0.002" interference.
Click to expand...

Exactly what I am deriving here....

Kelly Timoffee said:
I got 0.0015" interference with a 0.012" wall thickness(turned)
Click to expand...

On this end .0015 on .011 neck thk

Kelly Timoffee said:
I was however able to get another half thou or so by turning the die in a half turn and putting a heavy hand into the press , well, pretty heavy actually.
Click to expand...

Ditto here.

Kelly Timoffee said:
May have to look at that smaller mandrel.
Click to expand...

Yeah...realizing that now, thanks to the posts.

Kelly Timoffee said:
I prefer factory machining to back yard stuff but a polish may get you where you need.
Click to expand...

Me too...just thinking about ETA of custom mandrel. The resources are around here to try...so I will give it a whirl. You should see my home made dry lube applicator R:d:

Much obliged for your time Kelly!

Ron
 
laurencen said:
without a mandrel the diameter will be dependent on the die sizer and neck wall thickness, if you have the thickness smaller by 0.001 the inside diameter will change by 0.002, the whole idea of the mandrel is using the sizer reduce the diameter by less than required and stretch with the mandrel to size, this method allows for different wall thicknesses and keeps the inside diameter constant,
Click to expand...

Laurencen, thanks for sharing.

Right. Good explanation. Keeping the i.d. constant is the purpose of the mandrel and without it, higher probabilities of inconsistency. I get it.

To be really truthful, I removed the mandrel to understand what was going on. My hypothesis was with fresh neck turned (fired brass) that the probability of introducing inconsistencies was small because of how the collet die closes uniformly around the neck. I now know that the collet design has the ability to squeeze the neck smaller than current mandrel dia which is good to know anyways. Lee instructions indicate that rotating 180 degrees for a second cycle through the die will help reduce runout, and with that method, I thought that operating without the mandrel (in this situation) may have merit. Self centering of a chamber fitted case is what I was thinking, and with my take of the Lee O ring design proposing die self alignment, (self die alignment may be incorrect?) that the two would work together as opposed to apart.

Again, appreciate your response and time Laurencen

Regards
Ron
 
RonR said:
Laurencen, thanks for sharing.

Right. Good explanation. Keeping the i.d. constant is the purpose of the mandrel and without it, higher probabilities of inconsistency. I get it.

To be really truthful, I removed the mandrel to understand what was going on. My hypothesis was with fresh neck turned (fired brass) that the probability of introducing inconsistencies was small because of how the collet die closes uniformly around the neck. I now know that the collet design has the ability to squeeze the neck smaller than current mandrel dia which is good to know anyways. Lee instructions indicate that rotating 180 degrees for a second cycle through the die will help reduce runout, and with that method, I thought that operating without the mandrel (in this situation) may have merit. Self centering of a chamber fitted case is what I was thinking, and with my take of the Lee O ring design proposing die self alignment, (self die alignment may be incorrect?) that the two would work together as opposed to apart.

Again, appreciate your response and time Laurencen

Regards
Ron
Click to expand...

Try a 1/8 turn instead of 180 degrees...I think you may understand the reason once you have viewed the collet. Works for me but I have never measured for run-out. I don't remember where I read this but I subscribe to the theory!
 
The run out from a collet die when used properly is surprisingly low.

No difference really in comparison to a bushing style.


blauber said:
Try a 1/8 turn instead of 180 degrees...I think you may understand the reason once you have viewed the collet. Works for me but I have never measured for run-out. I don't remember where I read this but I subscribe to the theory!
Click to expand...
 
If you want to play with variations in neck tension and still maintain the sizing accuracy you'll get from the mandrel perhaps ask around in your club or perhaps you already know of some home shop guys with a lathe. It's not a big deal to churn out such mandrels and keep the size accurate to within 1/4 thou. At least not for most folks with a lathe that likely dabble with home gunsmithing projects.
 
blauber said:
Try a 1/8 turn instead of 180 degrees...I think you may understand the reason once you have viewed the collet. Works for me but I have never measured for run-out. I don't remember where I read this but I subscribe to the theory!
Click to expand...

I get that and can understand the logic. And I stand corrected...the instructions say "one half turn" not 180 like I posted but I interpret it to mean the same. To be truthful again, I just spin the case a between a quarter and a half turn for the second pass. I believe Kelly's statement that when used properly the result from a lee collet die should be low runout. I haven't graduated to that level yet to measure runout but if I ever get the itch to find out...I will.

I've learned from Mystic, Kelly, Hitzy, Yodave, Dogleg plus many more here that process is king and that describes me to a T.

Thanks Blauber.

Regards
Ron
 
BCRider said:
If you want to play with variations in neck tension and still maintain the sizing accuracy you'll get from the mandrel perhaps ask around in your club or perhaps you already know of some home shop guys with a lathe. It's not a big deal to churn out such mandrels and keep the size accurate to within 1/4 thou. At least not for most folks with a lathe that likely dabble with home gunsmithing projects.
Click to expand...

:dancingbanana: Higginson has a reduced mandrel in stock!!! Go figure. Just have to stick with that purchase instead of the Costco shopping cart syndrome to make the order worthwhile :rolleyes:

I appreciate the vote of getting it done here BCRider.

Ron
 
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