Lee Collet Sizer Modification

[Rockydoc]

In an article in The Fouling Shot, the publication of the Cast Bullet Association, I read about a modification of the collet leaves in a Lee Collet Neck Sizer. The top end of the leaves are shortened .03" so that the very end of the mouth of the case is not squeezed down when the rest of the neck is sized down. This in effect leaves the case sized and belled all at the same time. This would eliminate the steps of neck expanding and belling.

The fly in the ointment is that, according to the author of the article, you need a lathe to do this. You must sacrifice a cartridge case as well.

Well I can sacrifice a case as well as the next guy, but I don't have a lathe and I don't know how to use one.

Has anyone here done this? Must you have to do it on a lathe?

 

[Ian]

I didn't read that particular article but knwe about it and intend to try it at some point, probably on the .30-'06 die that I already modified here. I suspect you not only need a lathe, but a tool post grinder as well because those fingers are made of spring steel. I would not shorten the collet fingers but would cut a bevel and a step on the inside where they come together (think "counter-bore"). The tips of the fingers aren't all that critical for engaging the tapered crimping collar but I would want the mouth of the case supported so it remains concentric with the rest of the neck.

 

[Gary]

Way above my pay grade!

 

[Rockydoc]

I didn't read that particular article but knwe about it and intend to try it at some point, probably on the .30-'06 die that I already modified here. I suspect you not only need a lathe, but a tool post grinder as well because those fingers are made of spring steel. I would not shorten the collet fingers but would cut a bevel and a step on the inside where they come together (think "counter-bore"). The tips of the fingers aren't all that critical for engaging the tapered crimping collar but I would want the mouth of the case supported so it remains concentric with the rest of the neck.

That would still need a lathe??

 

[Spindrift]

The concept is really appealing. I love my collet dies, and use them whenever I can. If I could omit the belling/expanding operation, I would save some time.
I don’t have a lathe either. But my gunsmith has one, and his work isn’t to expensive. This modification, with Ian’s mandrel, would be the perfect die for me.

 

[Rockydoc]

I don't know of a real gunsmith anywhere near me. There is a retired machinist in my neighborhood but he is expensive.
I guess I will just muddle on expanding/belling changing dies between.

 

[Ian]

I don't see why you couldn't just clamp the fingers together with a hose clamp and grind the tips off with a bench grinder or even an angle grinder id shortening is all that is required.

A tool post grinder is a rare and expensive lathe attachment that enables working on materials which are too hard to cut with edged tooling.

 

[Maven]

I used a cut-off wheel in my Dremel to remove the amount mentioned by John Alexander. My .30-06 collet didn't require any modification, but I did modify my .243Win. collet: I couldn't see any improvement at all.

 

[Rockydoc]

I don't see why you couldn't just clamp the fingers together with a hose clamp and grind the tips off with a bench grinder or even an angle grinder id shortening is all that is required.

A tool post grinder is a rare and expensive lathe attachment that enables working on materials which are too hard to cut with edged tooling.

That is what I had hoped I'd hear from a lathe owner. I guess if I screw it up I can always buy a new collet finger part.

 

[Missionary]

If it is only .03 that needs removed I would do it with a diamond lap and the collet held in the jaws of a drill press to stay 90 degrees.

 

[Rockydoc]

If it is only .03 that needs removed I would do it with a diamond lap and the collet held in the jaws of a drill press to stay 90 degrees.

I don’t have a drill press. I have a diamond knife sharpening hone.