Lyman h&i die center pin dimension concerns

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  • Last Post 18 March 2021
corerf posted this 17 March 2021

I have measured a Lyman vintage h&i die that was marked .431 to get its dimensions. I found it sized a .433 round ball to .4305. A .431 minus gage didnt pass the top taper section.

The center pin was .429 minus a bit.

My directive: I lapped the die to .4315 dead nuts. I slugged it with a .433 RB and it is dead nuts with a nice taper up top. That was the target dimension.

The center pin is of course quite small now and it was already quite small. I haven’t tried to lube with it yet, concerned the lube will get past the center pin and get the base of every bullet funky.

Functionally- in “your” experience- how tight is tight enough for the ejection pin on a given die??

Do I need to turn a tight one (.0005 under)....... or can the pin be pretty loose as above, and still not leak?

Thanks in advance for the insight

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RicinYakima posted this 17 March 2021

I have done this several times and I make my pins .003" small. The reason is the lube is so thick (I use NRA) that if it is smaller it is too hard to push the bullet down and up. FWIW

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delmarskid posted this 17 March 2021

I've polished dies out and ended up with that kind of clearance. I don't have any real problems with lube on m bullet bases as long as I don't get too heavy twisting the down the lube pressure. Lube will ooze through the gap when no bullet is in the die. I just back off the pressure when I'm done. My lube is pretty soft. 

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corerf posted this 17 March 2021

Excellent news. I use WLL 2700 and it’s hard, very hard, unless the heater is plugged in for a bit or it’s summer here in Memphis.

Great news. I don’t need to make a new pin.

Anybody have an affordable .431 rcbs or Lyman sizer die they have excess? I’d like to have a second in hand. I do have a 445 SM that eats the Lee very well at .430 and I used the old die for it. Now likely too big for the 445. A .430 would work too,?I’ll have to open it up a bit but since it was so easy to adjust with fine precision I might as well make them what I need exact. I have a .429 to trade (several accumulated). I have concerns about concentricity if I am lapping open more than .001

That’s an offer to trade .429 for .431 or .430, any maker.

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Duane Mellenbruch posted this 17 March 2021

Are you having any significant alloy spring back with a harder cast bullet? 

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Bud Hyett posted this 17 March 2021

As reported above, my pins range from .002 or .003 smaller. The one exception was after I polished  .459 die .001 and it leaked.

I placed the pin into a vise and tightened a little. Measured and tightened more. After several iterations, felt some give and measured, the head area had swelled almost.002. This stopped the leaking. 

Farm boy from Illinois, living in the magical Pacific Northwest

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corerf posted this 17 March 2021

Duane I do get spring back and that’s the only way I’ve even been close to .431 with the factory die so small in measurement.

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Duane Mellenbruch posted this 18 March 2021

Corerf, thanks for the reply.

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