21st Century Expander Mandrels

[Gingerman]

Ordered the .306 & .3065 mandrels with the X die body for my 308 match loads I plan to make. I'm looking at .002 and .0015 interference fit. (Neck tension) I'm humming at .003 from my Redding FL die expander button. Works fine for semi-auto, but a single feed bolt gun FTR class rifle I think I want the stated neck tension. How accurate are these mandrels and any advice for lubing?

 

[Lawnboi]

Get the nitrided version if getting 21st century. Carbide is the way to go but those options are either dwindling or becoming very expensive.

I lube with a little bit of imperial on the rim, very little, then tumble it off.

On my amp annealed brass, sized minimally, usually .004 under, my expander mandrels (.001 under) yield too little neck tension. Turning mandrels (.002 under) usually yield .0025 tension.

This is all relative, as is what ever you read because depending how you anneal, your neck thickness and your sizing die you could end up with different results. On a normal fl sizing die, it usually squeezes the piss out of the necks. You could likely use a mandrel .001 under bullet diameter and end up where you want to be. Squeezing the brass so much followed by expanding also leaves you with a lot of work placed on it, usually ending up in neck tension variation.

Does all this matter? I don’t know. I have moved to SAC dies and size the neck .004 under, and expand with a mandrel .002 under bullet diameter. This leaves me with an average .025 neck tension.

 

[Gingerman]

Get the nitrided version if getting 21st century. Carbide is the way to go but those options are either dwindling or becoming very expensive.

I lube with a little bit of imperial on the rim, very little, then tumble it off.

On my amp annealed brass, sized minimally, usually .004 under, my expander mandrels (.001 under) yield too little neck tension. Turning mandrels (.002 under) usually yield .0025 tension.

This is all relative, as is what ever you read because depending how you anneal, your neck thickness and your sizing die you could end up with different results. On a normal fl sizing die, it usually squeezes the piss out of the necks. You could likely use a mandrel .001 under bullet diameter and end up where you want to be. Squeezing the brass so much followed by expanding also leaves you with a lot of work placed on it, usually ending up in neck tension variation.

Does all this matter? I don’t know. I have moved to SAC dies and size the neck .004 under, and expand with a mandrel .002 under bullet diameter. This leaves me with an average .025 neck tension.

I just saw this. I got the die and mandrels in today. I got .306" & .3065". My Redding standard A die sizes the necks to ID of .3055". The .3065" mandrel goes in with just a slight kiss and brings the ID to .3065" on the money. My bullets are .3085". So, I effectively have .002" neck tension. I will get a .307" for the .0015". (Seating force was still more than I want) I'll grab an XL die too for the 300WM.

 

[ryleecarr2006]

I use imperial dry neck lube.

 

[Bater]

I have 21st mandrels for most every caliber (.002" nt) and they have been spot on. I personally use a little RCBS lube on the mandrel and on the inside of the necks. Then I run a patched brush through necks to remove all lube. I have crushed a few cases when using the cheap Lyman dry neck lube....it is quite literally worthless. Good luck

 

[Dos XX]

Is your die a bushing die? If so, try ditching the expander ball and just size with a bushing to slightly under your desired size, then use a mandrel to bring it up.