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It should be 85mm (3.4") in length, it may be the angle you've photographed it at but that looks a bit longer.

The "ring" is normal, that section has a slightly different angle to the rest of the taper.

Here's a new one for comparison.

I think that the length of the Expander plug is irrelevant to this case: if it were too long, then it would be acting on the bottom of the case, if too short the case would get stuck between the plug and the wall of the die, and not be able to push anything up.

Also don't forget that the expander plug acts on the downstroke of the ram, not on the upstroke; on it's way up, before it's been resized, the case should easily clear the expander plug. On its way down, the resized case is forced over the plug to bring the case-mouth back to the proper inside diameter. That's why the shiny ring in the OP's photo is in the wrong place, it should be right at the top of the expander plug.

Instead it shows that case is contacting the expander plug low down and on the upstroke, getting stuck on the plug because it's the wrong size. Being unable to go over the plug, it collapses the case neck and eventually pushes out the expander stem and decapping pin.

The expander plug is too big. I've measured mine and it's .307 at widest, giving 1 thou of neck tension for a .308 bullet. I'd guess you've got a .322 one for 8mm Mauser, or perhaps a .310 one for .303 / 7.7 Jap.

Triffid

Chuck the expander away and buy a Lee decaping die job done.

As you are spending a fortune on an AI why not ditch the Lee dies and get a decent set of Redding, Forster or Whidden Dies.

Hi chaps, sorry for the delay, I am currently having to visit my mum every other day as she had a massive heart attack two weeks ago and is currently still in the cardiac unit at Peterborough Hospital, which is 60 miles away from me, this severely restricts the time I have for "playing".

I have this afternoon measured my decapping pin with my digital vernier calipers. They're not brilliant but I have uploaded yet another photo, this one called "sizer probe"

John - Ive got a set of Redding dies but as I'd heard such good things about the Lee dies, especially the neck sizing collet dies, providing superior "run out" etc. I thought I'd tried them. Unfortunately I didn't get as far as the neck sizer due to needing to full length resize the cases for the new rifle/chamber. When I do use the neck resiser I hope I don't have the same issues I've found with the full length one.

Phaedra & Triffid - The measurements you guys have shown/quoted in your posts seem to concur with those I've taken with my cheapo vernier calipers.

Alpha2 - Throwing away a brand new set of dies and buying a universal decapper doesn't seem to make much sense to me, I'd rather try and find a solution to the problem I appear to have. Anyway, my redding full length sizer works perfectly well.

Cheers guys
Bob

Alpha2 - Throwing away a brand new set of dies and buying a universal decapper doesn't seem to make much sense to me, I'd rather try and find a solution to the problem I appear to have. Anyway, my redding full length sizer works perfectly well.

Cheers guys
Bob

I'm not suggesting you throw away the dies I am suggesting you just ditch the de capper expander rod just use the die to size the case you don't need the expander button.

Think about it how does a bushing die work. Bushing dies do not have a expander do they. A de capping die is cheap as chips and they all ways come in use full.
If you all ready have a redding full length die why didn't you just buy a Collet die on its own.

Throwing away the expander/decapper rod is the best thing you could do, not because just because yours seems out of spec for the calibre but because all expander balls are an abomination and the work of the devil.

I throw them away from all my dies regardless of make and replace them with ordinary decapping rods, which lee supply, or one of a smaller calibre so that they don't touch and abuse my case necks.

No need to buy a another die either.

why do companies put them there, if they dont do anything?

I don't know why the manufactures include expanders rather than de capping pins. The case rides over the ball some times not very easily and it opens the neck the die full length resizes and squeezes the case neck to the correct size the case is then dragged back over the ball some times with a bit of a struggle and it opens it up SLIGHTLY.(WHY) You don't need to do this. Why resize a case then open it up again. I use LeWilson bushing dies for nearly all my reloading. My re loads works fine and there is not a expander in sight in any of my set ups. Except for dedicated expanders for cast boolits of course.

Alpha1 wrote:(WHY) You don't need to do this. Why resize a case then open it up again. I use LeWilson bushing dies for nearly all my reloading. My re loads works fine and there is not a expander in sight in any of my set ups. Except for dedicated expanders for cast boolits of course.

Because:

With a bushing die you select a bushing to match the neck thickness of your specific brass, so the result is the desired neck-ID/neck-tension (albeit sized from the outside, so best used with neck-turned brass).

With standard one piece (non-bushing) dies you don't have that flexibility. These dies have to cope with the thinnest brass they may encounter and still give reasonable neck-tension; therefore, using thick brass without any expanding will result in a much smaller ID (high neck tension), and can even lead to collapsed necks on seating, or basically using the bullet as an expander.

Personally I like one-piece dies, so that the body, shoulder and neck are supported and formed in relationship to each other. A consistent ID that is round and concentric can then be achieved with a suitable floating expander mandrel, such as the Sinclair carbide or 21st Century TiN ones, without exhibiting the increased runout that is often seen with expanders in sizing dies (or M dies).