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wncchester · May 24, 2011, 08:30 PM

"IMHO that aluminum plug is really a mechanical fuse that is intended to shear when too much force is applied inside the die. The amount of pressure on the plug when 20 pounds of force is applied to the handle is different from one model press to another.."

Exactly so, for both points.

Thing is, the only 'instructions' Lee can reasonably give for that collet neck die is for their own presses, it wouldn't be possible or even helpful to make a long list of variations for others (that would keep most people from reading even the short instructions they do give).

Like you, I understood what the collets were supposed to do from the first and carefully experimented with my first such die in my Rock Chucker (I didn't read the instructions because I didn't have a Lee press at that time). It has a moving part so there is a definate learning curve to using that die successfully no matter what press is used or the written instructions provided.

I soon learned the collet neck die works quite well in an RC when done correctly (even with the much dreaded "cam-over"!

) Now, many years later and with more than a half dozen collets in my gear box, I've never stripped a die top out and my accuracy is quite good, at least better and more consistant than I've ever obtained with any of my conventional neck dies. And, with my contricity gage, I can prove the run-out is less.

Yes, I too feel differences in seating pressure when using the collet dies... same as I do with any other sizer, FL or neck! And that's even after I lightly turn the necks to help uniform the thickness for better concentricity.

I can't prove it but I suspect much of the perceived seating effort difference comes from small variations in the brass alloy OR the numbers of times it's been work hardened by firing and reloading. I used to worry - a little - about that but I've also come to suspect the case walls and necks are often slammed hard against the chamber walls even before the bullets fully exit the neck ; if so, grip "tension" has less effect than some believe.

May 24, 2011, 08:30 PM	#56
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	"IMHO that aluminum plug is really a mechanical fuse that is intended to shear when too much force is applied inside the die. The amount of pressure on the plug when 20 pounds of force is applied to the handle is different from one model press to another.." Exactly so, for both points. Thing is, the only 'instructions' Lee can reasonably give for that collet neck die is for their own presses, it wouldn't be possible or even helpful to make a long list of variations for others (that would keep most people from reading even the short instructions they do give). Like you, I understood what the collets were supposed to do from the first and carefully experimented with my first such die in my Rock Chucker (I didn't read the instructions because I didn't have a Lee press at that time). It has a moving part so there is a definate learning curve to using that die successfully no matter what press is used or the written instructions provided. I soon learned the collet neck die works quite well in an RC when done correctly (even with the much dreaded "cam-over"! ) Now, many years later and with more than a half dozen collets in my gear box, I've never stripped a die top out and my accuracy is quite good, at least better and more consistant than I've ever obtained with any of my conventional neck dies. And, with my contricity gage, I can prove the run-out is less. Yes, I too feel differences in seating pressure when using the collet dies... same as I do with any other sizer, FL or neck! And that's even after I lightly turn the necks to help uniform the thickness for better concentricity. I can't prove it but I suspect much of the perceived seating effort difference comes from small variations in the brass alloy OR the numbers of times it's been work hardened by firing and reloading. I used to worry - a little - about that but I've also come to suspect the case walls and necks are often slammed hard against the chamber walls even before the bullets fully exit the neck ; if so, grip "tension" has less effect than some believe. Last edited by wncchester; May 25, 2011 at 08:48 AM.