Who makes the BEST expander mandrel?

[timeout]

I am not going to bicker as to why I feel I need one and you don't. I see scoring inside my necks, I need one, I'll pay the price. I will try polishing my first mandrels first. I have scored necks on what could be considered fairly minimal expansion. I have also been known to neck up cartridges to a larger caliber. I don't consider myself an expert at neck sizing, but I have a lifetime of experience in mechanical operations. I'm just looking for a better way. Perhaps polishing my mandrels will be the solution?

 

[DanConzo]

The expander mandrel has to be a close fit to the turning mandrel regardless who makes it, a mirror polish finish doesn't hurt and neither does carbide, but the ids have to be very close to one another for each case or it doesn't matter what you use. In my experience anyway. I know people using a different manufacturers's tools and systems and still don't get under .0005" consistent wall thickness case to case.

 

[jlow]

I am not going to bicker as to why I feel I need one and you don't. I see scoring inside my necks, I need one, I'll pay the price. I will try polishing my first mandrels first. I have scored necks on what could be considered fairly minimal expansion. I have also been known to neck up cartridges to a larger caliber. I don't consider myself an expert at neck sizing, but I have a lifetime of experience in mechanical operations. I'm just looking for a better way. Perhaps polishing my mandrels will be the solution?

Everyone has a right to buy what they need to get the results they want – that is clear. Was not saying you cannot, just trying to understand why you are getting the scoring and the tight necks which you say is responsible. Try the polishing and Imperial, if it does not work for you, go for the carbide.

 

[amlevin]

When I started this thread I was really thinking "Who makes the SMOOTHEST expander mandrel?"

The mandrel on my Forster Neck Turning Tool is infinitely smoother than the mandrel in my Sinclair Expander Die. It appears that it was either turned with a "Pointed" tool or ground with a coarse gringing wheel. Maybe I'm deluded but I would have expected the finish to be more like what I find inside my "upper end" sizing dies.

Carbide, as I understand it, has a far lower coefficient of friction when rubbing on brass. Also doesn't wear so a higher cost in the beginning would translate to a "one time purchase" rather than having to replace due to wear.

Based on the replies, smooth is the consensus. Unless someone can point to a maker of carbide mandrels I guess I'll just resort to polish, polish, polish, and see how it goes.

 

[DanConzo]

amlevin--Sorry I got carried away on the neck turning part which wasn't really answering your question. I agree w/ you on the Forster mandrels and I also think a lot of their tools especially the neck turning attachment for their trimmer or lathe setup is a great tool much overlooked for newer tools probably advertising and so called expert opinion. Polishing mandrels is a good practice. If you have any JB bore paste around (the good stuff) load it on a dedicated cotton buff wheel to polish it. It really works, but so does other methods.

 

[jlow]

Just for reference, there is how my two 308 mandrels look like today.

The top one is the Sinclair expander, and the bottom one is the K&M neck turning expander. Only the part that contacts the case were polished a couple of years ago and so you can see the shine still present at their tips. For comparison, the unpolished top part of the mandrels is still visible. The “working” part of the mandrels are no longer mirror smooth having been used now for thousands of cases but they are still smoother than the untreated parts.

As already mentioned, I use “No. 7 Rubbing Compound” and a drill press to do this.

 

[DanConzo]

jlow--Good picture. No 7 is good stuff. Also good for over- shiny gunstocks wood or synthetic.

 

[jlow]

Thanks! That stuff is also good for taking off any galling - as I found out when I first started out doing this! ;D

 

[queen_stick]

The expander from 21st century is fantastic. Used with lube (RCBS), I almost can't feel the case sliding over the mandrel... it's that smooth.

With that said, their expander mandrels are made to expand the neck just enough to fit precisely on their neck turner. It does a very good job of that! I don't know how well they work for making wildcat cartridges or other 'forceful' operations. (like necking up a .224 to .243, as an example). I haven't tried anything like that with their expanders.