Lee Collet Neck Die

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I Dont Care About You

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I got a Lee Collet neck sizing die for my 303.

The instructions say to adjust the die so the press does not cam over. Also says to apply ca 25 lbs of pressure to the handle. Apparently my perception of 25 lbs is different from what the die was designed for.

I find that no matter how much pressure I put on the press handle, the neck tension when seating the bullet is very light. I have been crimping bullets after seating because the neck tension seemed so light.

Anyway, after sizing less than 100 cases, the top cap of the collet die shed its threads. I ended up making a new top cap out of steel (benefits of a home machine shop). I have reset the die in the press so the press does cam over but only with a small amount of pressure. To me, this allows the calming pressure to be much more consistent from case to case.
 
I size twice, turning the case 180 degrees, what is your neck tension? measured before and after?

You can get undersized mandrels if you want more tension.

You don't want cam over...and 25lbs is not very much.

How hard are your cases?? You might want to anneal.
 
I experienced the same especially when loading .303 with bullets from Russian 7.62x54r, so to overcome this insufficient neck tension I use the mandrel from the LEE collet 7.5x55 Swiss, works great.
Of course I could also machine the mandrel down a bit but haven't done it yet.
 
hawk-i said:
I size twice, turning the case 180 degrees, what is your neck tension? measured before and after?

You can get undersized mandrels if you want more tension.

You don't want cam over...and 25lbs is not very much.

How hard are your cases?? You might want to anneal.
Click to expand...

Cases are annealed.

I have no means to measure neck tension. Only going by what seating the bullet feels like.
 
M1-Garand said:
I experienced the same especially when loading .303 with bullets from Russian 7.62x54r, so to overcome this insufficient neck tension I use the mandrel from the LEE collet 7.5x55 Swiss, works great.
Of course I could also machine the mandrel down a bit but haven't done it yet.
Click to expand...

Is there a way to get a different mandrel that doesn't involve buying another die from which to scavenge from?

I considered putting the mandrel into the lathe and sanding it down slightly but the chances of getting it perfectly straight is .....
 
Maybe check with LEE, another mandrel may be available.
I measured mine, the one from the .303 set measures 7.84 mm, the one from the Swiss 7.55x55 measures 7.78 mm, so it would not be that hard to machine it down.
 
The back of the Lee instruction sheet may say you can order a .002" undersize mandrel. I did that to get a tighter fit on another calibre.
 
Hmm.. If you anneal the necks, it becomes much easier to seat the bullets. Perhaps you should check neck tension some other way - compare to a non-annealed case?, etc.
 
I Dont Care About You said:
I got a Lee Collet neck sizing die for my 303.

The instructions say to adjust the die so the press does not cam over. Also says to apply ca 25 lbs of pressure to the handle. Apparently my perception of 25 lbs is different from what the die was designed for.

I find that no matter how much pressure I put on the press handle, the neck tension when seating the bullet is very light. I have been crimping bullets after seating because the neck tension seemed so light.

Anyway, after sizing less than 100 cases, the top cap of the collet die shed its threads. I ended up making a new top cap out of steel (benefits of a home machine shop). I have reset the die in the press so the press does cam over but only with a small amount of pressure. To me, this allows the calming pressure to be much more consistent from case to case.
Click to expand...

I had the exact same problem (and others) with this die for 223 in my old Rockchucker. My solution to that problem was the same as yours (I let it cam over).

The bigger PITA that had with die in 223 and 308 was that the internal machining on these dies were chattered and rough.
I had to smooth them down because the die would stick in the up position.
And if you feed another case into when stuck, then its shoulder would collapse.
 
Compare the lever arm lengths, and resultant leverage between a Rockchucker and a Lee O press. While you may need 25 lbs force on the Lee press, you only need a fraction of that on the Rockchucker. I suspect a lot of collet dies have bit the dust as a result.
Camming over gives the linkage maximum leverage, which can also lead to too much force on the collet. BTW - The top cap acts as a stop for the collet assy, which slides up and down. Given that you broke the threads on the cap, I think one can conclude that too much force is being applied.
 
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Munkey1973 said:
I had the exact same problem (and others) with this die for 223 in my old Rockchucker. My solution to that problem was the same as yours (I let it cam over).

The bigger PITA that had with die in 223 and 308 was that the internal machining on these dies were chattered and rough.
I had to smooth them down because the die would stick in the up position.
And if you feed another case into when stuck, then its shoulder would collapse.
Click to expand...

I had this exact thing happen. I thought maybe the caming over of the press caused the parts to get jammed together. I was kinda rethinking the caming over ploy. How did you solve it?
 
cosmic said:
Compare the lever arm lengths, and resultant leverage between a Rockchucker and a Lee O press. While you may need 25 lbs force on the Lee press, you only need a fraction of that on the Rockchucker. I suspect a lot of collet dies have bit the dust as a result.
Camming over gives the linkage maximum leverage, which can also lead to too much force on the collet. BTW - The top cap acts as a stop for the collet assy, which slides up and down. Given that you broke the threads on the cap, I think one can conclude that too much force is being applied.
Click to expand...

Yea, I get that I was applying too much force but I managed to do that prior to setting the die up to allow the press to cam over.
 
M1-Garand said:
I experienced the same especially when loading .303 with bullets from Russian 7.62x54r, so to overcome this insufficient neck tension I use the mandrel from the LEE collet 7.5x55 Swiss, works great.
Of course I could also machine the mandrel down a bit but haven't done it yet.
Click to expand...

Me neither because the chances of getting a nice smooth surface like the original is pretty low.
 
I Dont Care About You said:
I had this exact thing happen. I thought maybe the caming over of the press caused the parts to get jammed together. I was kinda rethinking the caming over ploy. How did you solve it?
Click to expand...

I had to disassemble the die and sand & polish out the chatter marks from when Lee turned the angled parts of the die on the lathe.

I'd say that 80% of the chatter was on the bottom part (the one with the slits). Wasn't too bad on the top part that buts up to the cap.

The chatter marks make them stick....you'll want them smooth as glass.
If you made a replacement cap for the factory aluminum one that sheared on you, then certainly you have a lathe... which make quick and efficient work of that.
 
I Dont Care About You said:
I had this exact thing happen. I thought maybe the caming over of the press caused the parts to get jammed together. I was kinda rethinking the caming over ploy. How did you solve it?
Click to expand...

I had to disassemble the die and sand & polish out the chatter marks from when Lee turned the angled parts of the die on the lathe.

I'd say that 80% of the chatter was on the bottom part (the one with the slits). Wasn't too bad on the top part that buts up to the cap.

The chatter marks make them stick....you'll want them smooth as glass.
If you made a replacement cap for the factory aluminum one that sheared on you, then certainly you have a lathe... with some fine sand paper will make quick and efficient work of that
 
M1-Garand said:
Maybe check with LEE, another mandrel may be available.
I measured mine, the one from the .303 set measures 7.84 mm, the one from the Swiss 7.55x55 measures 7.78 mm, so it would not be that hard to machine it down.
Click to expand...

I did a little digging. The Lee Precision website lists the following information for mandrels:

Case Size SKU
303Br: .3085 NS2628
7.5x55: .3055 ZZ3462
308W: .3055 NS2627

Not sure why the 7.5x55 and 308W mandrels have different part numbers? The 308W, 30-06 and 30-30 mandrels have the same part number?

A little further digging shows that Rusty Wood Trading lists the mandrels for sale for a mere $4.75. Think I'll get one and try it. ;)
 
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Chuck the mandrel in a lathe, get a strip of emery cloth, and a good micrometer, away you go
Click to expand...

I agree with cosmic on this. I have 5 or 6 collet dies and have sanded down most of the mandrels for a bit more neck tension. No amount of extra pressure will reduce the inside neck size, the mandrel is pretty hard. After popping my first cap out Lee sent me a couple of extras, no charge. They also informed me that aluminum was used for the cap as a release point for too much pressure. Polishing the chatter marks is also a good idea for smooth operation.
 
Best neck dies out there. Perfect straight necks every time and no lube needed.

But they have to be used correctly. You may need a smaller mandrel I have polished a couple 1 thou smaller cause they came too big. You can get spare mandrels and polish them to whatever you want.

Also the cap is made of a soft material on purpose, kinda a fail safe if you will. It will blow out if too much force is applied so you don't damage the rest of the mechanism.

After a while you can litterly feel the neck give/size. If brass is annealed and or has nice soft necks you can especially feel this. Hard stiff about to crack necks not so much.
 
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