Expanding Mandrels

[SDHNTR]

This biggest issue is from mass produced dies designed to size a case to an extreme amount (to cover everything) then run a .001 under button through. This can cause issues around the shoulder neck junction.

I think a button could be employed successfully if you were to control the diameter of the neck being sized, and the button size.

I “mandrel” similar to how a button would in my SAC dies as the brass leaves the die, the difference is I control the neck and mandrel size, and I also start the mandrel process as soon as the brass leaves the neck. I have seen zero difference using this method, besides a little less in the pocket book.

That’s exactly what I do. I use a bushing die with a carbide button and just squeeze enough so that I feel the button barely running back through the neck. I still can’t see what advantage a mandrel would give me. And it’s an extra step.

 

[HuntHarder]

That’s exactly what I do. I use a bushing die with a carbide button and just squeeze enough so that I feel the button barely running back through the neck. I still can’t see what advantage a mandrel would give me. And it’s an extra step.

I am not sure anyone is trying to talk you into it. Mandrels are pretty cheap if you want to experiment for yourself. If you are happy with where you are at, I would not change a thing. Some of us have noticed better spreads using a mandrel. I am not saying you will, but I did. I like to "tinker." It may be in my head, but I also notice a more consistent pressure when seating bullets if I mandrel. I use 21st century FWIW.

 

[Harvey_NW]

That’s exactly what I do. I use a bushing die with a carbide button and just squeeze enough so that I feel the button barely running back through the neck. I still can’t see what advantage a mandrel would give me. And it’s an extra step.

That process might not see any benefit because you're minimizing brass movement and probably aren't dealing with the same amount of springback. My assumption about a mandrel making a difference was in reference to a standard FL sizing die, where there is more movement. I could see running the neck over a mandrel with 100% of the surface area being expanded to the same diameter with a second or two of dwell time providing a more consistent result than just pulling a button through that is only expanding the portion of the neck it's touching while being pulled through.

Bushing dies are also 2x+ the cost, and don't size the entire neck potentially causing a donut.

Although I haven't noticed any issues on target, I'm intrigued. I plan to test it for myself and see if it's worth it.

 

[KyleR1985]

Then IMO opinion you're good using just bushings with no advantage to using mandrels. I use a plain bushing die with no expander ball and no mandrel's. As I said somewhere yesterday or today many LR BR and SR BR competitors would agree and do just that, bushing only no mandrel, no expander balls.

I’m dumb - just want to make sure I understand you here.

I have a Redding type S bushing die. The die I bought is loaded round neck diameter - .002.

You’re saying if I were you, you’d just pull the expander ball off the decapping pin, and full length size the brass with no internal work done to the neck, load and shoot?

 

[KyleR1985]

I just pulled the expander from my Redding type S bushing die, replaced it with the thinner decapping rod holder.

Fired brass neck measures .274”.

Sized 5 cases with .264 bushing and with the expander ball - all .264”.

Sized a case with a .264” bushing in the die, no expander ball. The neck measures .259”.


I pulled the .264” bushing out and measured its ID - .261”. Expander ball OD .240”.

How would not using the expander in this case make more sense than using it? I’d have a lot of neck tension it seems like.

The next step of using a mandrel to set ID makes sense this way. but to forego the expander ball and not use something to expand size of necks, I’d have to go to a bigger bushing. By my dumb math I’d think a .267”

What am I missing here?