How do you open the necks when making modifed cases for LNL comparator?

[tobnpr]

I've slit them with a thin wheel on a dremel.
I've repeatedly run a bullet coated with lapping compound in and out of the neck (collet in the press) which works but takes a lot of time.
No way I can figure out to hold the case perfectly concentric to skim the inside of the neck with a boring bar.

I'm thinking of turning a piece of stock a few thou larger than bullet diameter, putting a small taper on the end and pressing it into the neck.

What do you do?

 

[ricco1949]

Fire 'em then resize neck to a slip fit.

 

[V35]

I use gauge pins, MOST of the time it works, on a couple of occasions they were a little big or a little small.

 

[Bill Rodolph]

Throating reamer, chucking reamer, or expanding like you have said

 

[JFrank]

Fired case, no sizing. I want the shoulder angle to match the chamber as close as possible.

 

[WSnyder]

Oversized mandrel in the lathe or a fired case.

 

[Paul Hilgedick]

I use a small boring bar. Insert firied case in 3 jaw chuck with pressure from a center in tail stock. I have done more than a dozen this way. All have worked fine.

Paul H

 

[AlNyhus]

I use a case that's been fired in the chamber and minimally sized, if needed. On the neck, size with a bushing, etc. until it holds a bullet. Then open neck with a mandrel or wrap some 320 around a split wooden dowel and hone the neck until the bullet is a slip fit. A Wilson case holder in the lathe chuck makes it easy. Flip the case holder around, drill the primer pocket and tap it 5/16-36.

Good shootin' -Al

 

[tobnpr]

I use a small boring bar. Insert firied case in 3 jaw chuck with pressure from a center in tail stock. I have done more than a dozen this way. All have worked fine.

Paul H

Interesting, using a ts center to center up the (tapered) case when tightening the chuck jaws. I've got a 6-jaw Buck that should work well for this...

Doing some YT searching I came across a video from Cortina, he does it the same way I've been doing it with a bullet/lapping compound- but the boring bar looks faster; gonna give it a try.

 

[LVLAaron]

i built little collets for each parent case type I have... I do it all in the lathe, but also have made custom mandrels 2 thou over bullet size. Someone should make/sell those.

 

[Multiracer]

i built little collets for each parent case type I have... I do it all in the lathe, but also have made custom mandrels 2 thou over bullet size. Someone should make/sell those.

McMaster Carr, gauge pins, grind a slight taper and get an ER collet from Brunos.

 

[Multiracer]

 

[Sniperhandle]

View attachment 1716335

Don't let Hornady see it!

 

[LVLAaron]

Who makes the die? Not finding anything on Brunos

 

[Toolbreaker]

Die Bodies – Porter's Precision Products

portersprecisionproducts.com

Not sure what the OP is using, but the above link is an example. Uses off the shelf ER collets.

 

[tobnpr]

An ER collett serves the same purpose as the caliber-specific collets for a bullet-pulling die. No reason to re-invent the wheel for me.
I'll use gage pins w/ a taper ground at one end in the appropriate size collet and run the case up into it...
Good idea.