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Modify Lee Collet Neck Die?

You are just over complicating things and spending money on mandrels for no reason, what the OP is wanting to do is spot on and the LEE die will work perfectly
so what does the OD of the neck with other sizing methods in comparison to the collet after fire forming? Isn't a chamber cast to see where the collet is effectively causing the minimal clearance? I just can't see where collet die is so special.
 
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Depending on how much shorter the 338 NM is vs the 338 Lapua when you compare the base to shoulder/neck lengths, you may be able to cut the collet bottom that protrudes out the bottom of the die the same amount, build a shim the same length with a hole in it for the decap rod/sizer to go through and you ll be in business. The shim will go above the Lee collet cap that squeezes the collet and the threaded die top. If done properly the outside die body itself does not need modification. We've done 223 collet die like this and made a 221 fireball, done a 17 Rem and made a 17 hornet, etc. The 17 collet was the most we took off the bottom at .360-.370 …. The others we've modified typically are .100 to .200 depending on cartridge cases you re working with.

Good luck with your project.
That's what I was thinking early on.
 
so what does the OD of the neck with other sizing methods in comparison to the collet after fire forming? Isn't a chamber cast to see where the collet is effectively causing the minimal clearance?
The outside neck diameter won't change regardless of die used. The outside diameter of fired brass will be controlled by your chamber and brass spring back. The loaded round neck diameter is controlled by bullet diameter and brass neck thickness. Weather you size the neck to .001 or .005 under bullet diameter the brass will yield to your bullet during seating and loaded round diameter will be the same regardless.

To keep clearance right as far as neck diameter goes you need to spec your chamber reamer for it. I took the measurement of the exact brass and bullet I intend to use and specified the neck diameter of my reamer to be .005 over this because I don't want to neck turn and I feel a little more clearance is better on bigger cartridges.

For the die being made if I go full length non bushing sizer die I would specify it to size the neck .002 under bullet diameter. If I go full length bushing die I would buy a few bushing from .002 to .005 under bullet diameter. I would also specify for the die to bump the shoulder .002 under the fired brass measurement and minimally size the body.

There's lots of approaches to take to reloading and all can produce great results. My approach is to keep it simple and use as few steps as I can to the finished product (bullet) because I believe every extra step taken has the chance to introduce variance in the finished product. So ultimately I strive to minimally full length size for all my rifles.
 
Hey Biff, after re-reading your post it caught my attention that you stated "check there's enough length to go on the collet base before you get near the slots" can you explain this a little more?
some are split further down than this and I didnt look up your cases so am not sure how much you want to cut off. If you get too close to those cuts that make the collet fingers, u may find trouble. But that's the only possible trouble I could see. Shorten up the Pin to match the case too.
 

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I have modified a .260 Rem collet die for 6.5X47 Lapua. I used a mill file to shorten the bottom of the sleave that jams into the inner cone of the top part & shortened the mandrel. I then spun a Lee decap rod/pin, used in a Lee decap die, in my cordless & used a Dremel to reduce the diameter of the decap pin for the smaller sized flash holes in the 6.5X47L. This should work as the .338 Lapua case is longer than the .338 Norma.

Edit: forgot to mention I also used a hack saw to remove most of bottom of sleave.
 
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trying to save band width here

To keep clearance right as far as neck diameter goes you need to spec your chamber reamer for it
I take it you did that

the neck diameter of my reamer to be .005.... over
So when you mentioned minimal clearance how is that achieved when you're over ?
full length non bushing sizer die I would specify it to size the neck .002 under bullet diameter
you're loosing me here

I'm open to learning here.... sometimes it takes me a bit to get the full scope on things, so forgive me if I seem dense ! LOL
 
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I may need to start a new thread for this but just thinking about what I want to do and only needing this die to fire form brass what about using an RCBS or Hornady neck sizing die for 338 Norma mag? Do either of these dies have the shoulder cut in the die body? The only thing I need to worry about hear is if the improved shoulder on my brass will make any contact with the shoulder cut in the die if there is one. Anybody know?

I would rather use the Lee collet die but if a standard cheap RCBS neck sizing die will work on my improved case this would be the cheapest and easiest rout to take
 
From the pics I see of the different shoulders yes I would say you Imp shoulder would hit the die and interfere with neck sizing. It's a matter of just cutting off the base of the collet.. seems the easiest way to go Lonewolf
 
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Most folks don't know this, but Lee will make most anything if you ask. They will require a fired case or two, (which they will return) turn around is usually around month and the price is very fair. I have a hand full of Lee dies that Lee doesn't make.
The LEE custom shop is closed temporarily
 
Also to go the custom route through Lee for this particular die would $140. Little more then I wanna spend on it.

I found an RCBS neck sizing die for $15 which is hard to beat I just wish I knew if would contact the shoulder? It says it doesn't contact the shoulder but would it on an improved case?
 
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