Home Forums Reloading Big Game Rifles Modifying a Lee collet neck sizing die

Recently I put out a request for someone to modify a Lee collet neck sizing die to work for a .250 Savage AI. A standard .250 Savage die would work but Lee quit making them and they are scarce as hen's teeth.

Nsaqam modified this .257 Roberts die to work with a .250 Savage and I am happy to report it works perfectly.

Lee collet dies all use the same length body and decapping mandrel (for most cases, .223 sized use a shorter setup). The collet sleeve and the collet itself are cut to fit that one die body length. A shorter collet uses a longer sleeve and vice versa.

What nsaqam did was to cut a spacer to move the two pieces down for the shorter .250 Savage case, then machined off the bottom of the collet to keep the same overall length. You have to move that little shoulder on the collet as well. There is a corresponding lip on the inside bottom of the body to keep the collet from falling out.

In this picture the die on the left is for a .308, you can see the longer sleeve. The die on the right is the modified .257 Roberts die, the spacer is just under the cap.



A closer picture of the modified die.



This technique can be used to make any Lee collet die work for any shorter case within the same caliber. We could have used a .25-06 die for this. You just have to keep the collet/sleeve/spacer total length the same as the original collet/sleeve length.

A big tip of the hat to nsaqam for coming up with this and doing a very professional job on the machining.




Now, of course, in the meantime, I took my .250 AI to the gunsmith to fix a little problem with the extractor and probably won't get it back for at least two weeks. So now I have these wonderfully neck sized AI cases and nothing to shoot them in!

Great solution.

Very

And good on Nsaqam for getting you going. He is definitely one of the good guys!

Thanks for the kind words gentlemen.

This was an interesting project.
I was pretty confident the concept was sound but was unsure about how difficult the collet would be to machine.
It turned out that it machined very well.

Like Jim said, this mod would work on shorter cartridges than the one the LCD was made for if the case shape is remotely similar. The 300 Savage could easily be made from the 308 LCD for example.

Glad it turned out well Jim.

Hornady makes some excellent neck sizing dies for specific bore diameters that are useful on a wide variety of cartridges..

and this is not intended to undermine Nsaqam's ingenuity here..

I've used the Hornadys with great success.. and I am normally not a Hornady die fan.

So could you modify a 6.5 X 55 Lee collet Die to fit a 6.5 X 284?

KK, the length is easily dealt with.

Whether the fatter .284 case will fit inside the 6.5x55 collet is the question.

If someone has both a 6.5x55 LCD and a 6.5x284 case I'd be interested to hear if it does fit.

This is a wonderful topic since I have wondered about putting some 6.5 collet inside a 7mm mag to make a .264 Winchester. miles

If I understand the modification, you'll need a 6.5mm collet that's as long or longer than a 7mm mag unit. But I don't see one on Lee's list.

I keep thinking there should be some way to put a 6.5 collett and sleeve in a 7mm mag body. I just don't have enough different die parts to look. All that I have are based on .308 size cases. miles

The die body and the decapping mandrel are the same length for all LCD's that I looked at - .243, .30-30, .308, .270 and .30-06. The .223 die is much shorter. I don't have anything for a magnum case, especially a really long one like a .375 or .300 H&H so can't say if they make another set size for those.

The diameter of the die body is the same so any collet sleeve or any collet will fit inside. Obviously the mandrel must be the proper diameter for the caliber you are working with. Then the collet sleeve has a hole in it to match the diameter of the mandrel.

The collet sleeve - the top part that the collet is shoved up into and the collet itself make up a set total overall length that is the same from die to die. But the sleeve and collet will be shorter or longer so the collet only hits the neck of the particular case you are sizing. A shorter case gets a shorter collet but that mates up with a longer collet sleeve so the two together make that one standard overall length to fit in the standard die body.

Then, as nsaqam says, the body of your case has to be roughly similar in diameter to the case body the die is originally made for.

E.g., for the .250 Savage (or AI version) - the .257 Roberts LCD or the .25-06 LCD would have worked since they are all .473 case heads. You do have to pay attention to how much you need to cut off the bottom of the "donor" collet as you don't want to get up into the actual fingers of the collet. You could probably use a collet sleeve from a smaller diameter caliber and drill a larger hole in it for the larger mandrel but I don't know that for a fact.

You could use a shorter die with a longer case by putting a properly sized collar around each case head so it hits the bottom of the collet, and I've read a post here where someone does just that - he uses a washer IIRC to get the correct setting. To use a shorter case with a longer die you need to add the spacer inside the die and shorten the collet just as nsaqam did to the Roberts die shown in the pictures above.

The whole consideration is to keep that set overall length and any LCD will work for another case within the other general limits listed above.


I called Lee yesterday and cancelled my order for the custom .250 Savage AI dies. Have to admit to some slight trepidation when doing that but I have faith that nsaqam's modification will work for the rest of my lifetime at least. I polished the collet fingers and inside of the sleeve with 1000 grit paper and put lithium grease on those two parts. The only way to break these is to put too much pressure on your press handle and blow out the top of the die*, but then the die body and top cap are standard parts and easily replaceable from Lee.





*Okay, I'm sure some creative soul could bust them some other way, but that person probably has a spare room full of broken anvils as well.

Thinking about this, the collets are all the same external diameter and as far as I can tell the same slope and configuration at the top. Only the inner diameter and length of the collet differs from case to case, and obviously the shoulder angle is not critical since standard dies work for Ackley cases.

If a fellow had a chambering reamer for a 6.5X284 he could probably ream out the interior of a 6.5X55 die and make it work. Probably have to shorten the collet since AFAIK the .284 case if a tad shorter than the 55mm case.

That's off the top of my head as I don't have actual measurements of the two in front of me, but it seems like, as long as you are removing metal you can make almost any collet work for another case.

Opens up a world of possibilities.

Of course, Lee still will make up a custom set of dies for any case you send them, total cost is $60.

But this way is more fun...