Expander Mandrels — Precision options?

[Dub]

My only experience is with floating. I assume this gives a better chance of not introducing runout. I have no way to back that up though

 

[Patriot007]

I am changing neck dia on my short range guns as well as fooling with 2 new cartridges on my 600 IBS rifles and am currently using a Sinclair style floating die. With my current set up I can use the 21st century expanders but will need at least 12 of them for the 3 calibers. The Porter rig is about half ofthe price or less per expander but it is a ridgid set up and doesn't float. Just wondering what y'all think about ridgid vs floating... John

It would depend on which press I used it on. On My Forster Co-ax ,There would not be an issue, because the press will allow it to Free Float. Now if I were to use it on my lee C-press, there would be and issue because it will not allow it to float to achieve proper alignment. "So, Say the court" " I my self, have never had an issue with anything not aliening on the lee press" Just Me " ,,, If I wasn't heavily vested in the K&M and 21Century, I would definitely give them a try on my Forster Co-Ax. I am more of a Free Floating Fan Boy when it comes my dies and Stocks. JM2CW

 

[PopCharlie]

I am changing neck dia on my short range guns as well as fooling with 2 new cartridges on my 600 IBS rifles and am currently using a Sinclair style floating die. With my current set up I can use the 21st century expanders but will need at least 12 of them for the 3 calibers. The Porter rig is about half ofthe price or less per expander but it is a ridgid set up and doesn't float. Just wondering what y'all think about ridgid vs floating... John

I use my Porter die in a coax press. So the die floats a little.
PopCharlie

 

[PatMiles]

One plus with the Porter is the fact that you can buy individual gauge pins and collets (ER32) from online machine tool suppliers (MSC, Shars, etc.). You're not anchored to one supplier.

 

[mr45man]

That's getting complicated . IMO, just decide to use either a full length or neck size only bushing sizer die. Measure neck thickness x 2 + bullet diameter and get a bushing to give you 4 or 5 thou downsize to a fired case. Works necks a lot less than a traditional die that sizes the neck more than needed then expands it via the button as you withdraw the case.

Have not used a "button " in 20 years or more. Off the shelf dies are terrible.

 

[dkhunt14]

I am changing neck dia on my short range guns as well as fooling with 2 new cartridges on my 600 IBS rifles and am currently using a Sinclair style floating die. With my current set up I can use the 21st century expanders but will need at least 12 of them for the 3 calibers. The Porter rig is about half ofthe price or less per expander but it is a ridgid set up and doesn't float. Just wondering what y'all think about ridgid vs floating... John

I use one where the mandrel is locked in with a screw. I have seen no loss in accuracy with this setup and been using it for over 12 years. In fact i have set a few records doing it this way, 1000 yard BR. If the case is sized straight, the mandrel just follows the hole. The shellholder allows the cartridge to move and align with the mandrel. In fact i prefer to use full length dies without bushings. I believe the cases have less issues with run out. Matt

 

[PopCharlie]

Is this process similar to using a Lee collet die? Just with more precision because of the variety of mandrels?

It's a similiar process. There are 2 steps. The first step is full length sizing the case, with the expander assembly removed. The next step is to run the case over the expander mandrel mounted in a die. The neck is expanded by the mandrel to a very precise diameter. The Porter die uses pin gauges as the mandrel.

The Lee collet die squeezes the case neck against a mandrel via the collet. Most people use a 2 step process here also. A body die first, then the Lee collet die.

Both methods work well. IMHO, the expander mandrel is more precise. You can get mandrels ground to any size you need, to create very precise and consistent neck tension. The further advantage of the Porter die is that it is designed to use standard pin gauges. These gauges are available from many sources in many sizes. The Lee die can be custom made to precisely size the neck. It less expensive even if you get a custom die.

I have used both. I have used other mandrel dies as well. L.E. Wilson makes a very good one too, but you have to use their propriety mandrels. I have the Wilson die as well as a Sinclair. I prefer the Porter die.

PopCharlie

 

[SGK]

How far below your expander mandrel do you guys use for your neck bushing?

 

[Dusty Stevens]

How far below your expander mandrel do you guys use for your neck bushing?

I go .001 to .002. Its all according to brass springback

 

[dkhunt14]

How far below your expander mandrel do you guys use for your neck bushing?

I go small enough that it touches all of the necks. .001 to .002 is usually plenty. Matt