I have a 380PDK which was a blown out 280 case. I switched to a cylinder brass increased the case OAL to 2.6 to reduce my forming steps. Then had custom dies made.

Issue is now I've had to switch brands of brass. The new brass has a thinner neck. So my custom dies don't give me enough neck tension. Pulled the expander and it didn't help. So I picked up a Lee Collet 37H&H die. Shortened it to fit my 2.6". It helped but still not enough neck tension.

Since this is my first and only Lee collet die how do I increase the tension? Or can I? I "THINK" I can simply turn down the mandrel until I get the tension I want. Would prefer to hear from someone familiar before I simply start experimenting.

If I can't get the Lee to work will have to get a new sizing die made.

You have it right. Reduce the mandrel diameter to increase the crush from the collet. They are hardened, so polishing with abrasive cloth is what I usually do.

If you need a specific diameter, they are easy to copy on the lathe with some drill rod.

Jeremy

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on the lathe with some drill rod

Smart people don't let me touch a lathe.

Thanks. Will get by with a drill press and abrasive cloth.

The following reply is from a "sometimes" reloader vs. an addicted reloader.

I use Lee Collet Dies for a few bolt action rounds. After a few times reloading rounds with the stock mandrel and being able (sometimes) to move the bullet with finger pressure I order .001 or .002 under stock diameter mandrels from Lee. All have worked like a charm, get me more neck tension. Bullets in the magazine sliding back into the powder column from the massive, shoulder crushing recoil from my 7mm-08, 270 and 300BLK rounds no longer concern me. Probably could chuck them in a drill press with abrasive cloth but just order from Lee. Lazy? Obsessive/compulsive disorder? Both? Most likely both.

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After a few times reloading rounds with the stock mandrel and being able (sometimes) to move the bullet with finger pressure I order .001 or .002 under stock diameter mandrels from Lee.

But to order I have to plan ahead. Can't beat $5 and shipping.

Just MICd mine. The mandrel is .371 the brass after sizing reads .372 and the Nosler Accubonds are .373. The bullets surprised me. Measures some Speer 235gr and they are .374.

The Speer hold in the brass fine. So combination of wall thickness and undersize bullets??? Anyway the Noslers shoot subMOA so will work on the mandrel

That's funny. I'm the opposite and think a stock duplicator is a sure way to lose several fingers. Other than throwing the chuck key across the shop on occasion, I am fine on my lathe.

Jeremy

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Other than throwing the chuck key across the shop on occasion, I am fine on my lathe.

I launched the key from my drill press this week. Went to turn off the light hit wrong switch.

Unlike many I run my duplicator from the pilot side. I didn't like being around the router all the time and I think it reduces the chance I'll dig the bit in from too much pressure.

As to the mandrel. DONE success. I do think I'll go ahead and order an undersize as well. Can't beat the price.

Congratulations on your success.

In case anyone reading this is wondering how to accomplish reducing the Lee Collet mandrel by a thousandth or two, just chuck it in a drill press and hold a bit of fine emery cloth looped around it as the press spins. You'd be surprised how quickly a couple of thousandths come off.

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You'd be surprised how quickly a couple of thousandths come off.

Took as long to install in the press as it did to reduce the dia.

The mandrels neet some work amyway. Take off the sharp transition at the bottom amd polish them up a little. They work way smoother.

I've found mine were slightly too large in most cases.