Thread: First attempt at necking down 308 to 7mm08

Originally Posted by RimfireNZ

Lee for both. Apparently the Lee shell holders are a bit high, and hold the shell a bit low, so they don't stick the shell as far in the die as you may want.

That's what one of the guys at serious shooters said anyway.


Haven't had time to have another crack at it yet.

If you are over in Tuakau I have Hornady 7/08 dies... and you could bring your dies, fired case (in your rifle) and rifle and I could setup the shell holder to suit your case (lathe some off)... But just doubly make sure the shell holder is touching the bottom with the case it! when under pressure of sizing

A couple of things can go wrong/ different with the case in when FL sizing

1 Press stretch

2 The primer extractor pin can be set to low so it bottoms out inside the case

If its is definitly bottoming when sizing the case the shell holder or die will need to be modified

I also have a shell holder set with different heights for setting up head space.

I will PM my number if you want a hand

Originally Posted by leathel

If you are over in Tuakau I have Hornady 7/08 dies... and you could bring your dies, fired case (in your rifle) and rifle and I could setup the shell holder to suit your case (lathe some off)... But just doubly make sure the shell holder is touching the bottom with the case it! when under pressure of sizing

A couple of things can go wrong/ different with the case in when FL sizing

1 Press stretch

2 The primer extractor pin can be set to low so it bottoms out inside the case

If its is definitly bottoming when sizing the case the shell holder or die will need to be modified

I also have a shell holder set with different heights for setting up head space.

I will PM my number if you want a hand

Cheers Leathel, I might take you up on that actually. Let me just rule a few things out. I'll probably have a tinker tomorrow night when I get back from the range (my reloading room isn't at home so I can't do it now) so I'm a bit more prepared.

I got your PM. Cheers. Will get in touch.

So after reading through everyones posts again I figured I had a few more things to try. So after getting home from the range today I went to make doubley sure that my press was set up right.

It turns out the de priming pin (which was still in the die) was stopping the case from being able to go all the way in (only just) due to the increased neck thickness...

However... that brings me to my next issue... the neck thickness...



I tried seating a round just to see what'd happen to the brass.


I don't have the gear to be able to fix the neck thickness... so looks like I need to go in to the gun store and possibly go shopping!

Getting closer.

Doesnt seem right to me, did you put a nice chamfer on the inside? what does that round measure at the neck with projectile in it?

Seating die not set to low and trying to crimp onto pill?

Originally Posted by veitnamcam

Doesnt seem right to me, did you put a nice chamfer on the inside? what does that round measure at the neck with projectile in it?

Damn it, I was in a rush so no didn't chamfer it. There's part of the problem. I was doing half a dozen other things after coming back from the range and dropping a bullet in was an afterthought. And no the seating die isn't set too low on this one.

When you actually site a projectile in the necked down 308 brass, then do the same with the 7mm08 round you can really see that the round isn't gonna fit in the necked down 308. It needs trimming on the inside. I'll measure it up tomorrow when I'm back over there.

My house is too small so my reloading room is at my folks in town.

308 fed brass
308 left 243 center and right.





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It almost looks like you have put a 30cal pill in there?

Originally Posted by veitnamcam

It almost looks like you have put a 30cal pill in there?

Wow so you don't need to do anything to the neck even going down to 243? The thickness isn't an issue?

Let me try again with a chamfered case. Maybe I'm crushing the neck a bit.

As I said though, when putting the round in though the neck is obviously looking too thick.

That's a Sierra 140g 7mm boattail. I don't reload for 30 cal (SKS is my only 30 cal).

Thanks for your comments by the way.

I don't need to neck turn this brass in my(the wifes) rifle.
Neck turn is more about neck to chamber clearance allowing shell to release bullet and not blow up in your face.
Im right on the limit of having to neck turn this brass. Fired in the rifle a spent case will lightly hold a bullet before sizing.

I think you probably have another die or brass prep issue.

Get your longest bit of brass in press right up and wind seating die down till it touches and then up and half a turn.
chamfer all your brass generously inside and a touch outside.
Wire brush in a drill all your case mouths.
See how that goes

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Originally Posted by RimfireNZ

Damn it, I was in a rush so no didn't chamfer it. There's part of the problem. I was doing half a dozen other things after coming back from the range and dropping a bullet in was an afterthought. And no the seating die isn't set too low on this one.

When you actually site a projectile in the necked down 308 brass, then do the same with the 7mm08 round you can really see that the round isn't gonna fit in the necked down 308. It needs trimming on the inside. I'll measure it up tomorrow when I'm back over there.

My house is too small so my reloading room is at my folks in town.

Unless you are not using your expander in the FL die you will always need to outside turn if things are tight. 243 7-08 308 all going to form internally to the expander used not the die. Something looks proper fucked up with your cases. What's dies?

Originally Posted by kiwijames

Unless you are not using your expander in the FL die you will always need to outside turn if things are tight. 243 7-08 308 all going to form internally to the expander used not the die. Something looks proper fucked up with your cases. What's dies?

Just the basic Lee ones for 7mm08. I took out the decapping pin and I assume that's the expander? I can't actually resize the cases with that in. It doesn't get all the way in.

Take it out, put them through the fl die, then they measure up at least externally, but not internally.

Let me get some proper measurements for you guys tomorrow. Maybe that'll give you some more idea of what's going on.


This shouldn't be this hard, but i've only done factory ammo reloading before for a few calibers. That's easy cos you only need two dies and once it's set up, that's it

There is your problem
Fl die sizes down undersize then decapping rod/expander pulls it back up to size on out stroke.
Your die must have adjustment for the rod?
Set it down until it only just removes primer. It shouldn't bottom out in case.

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Also make sure necks are well lubed inside or expander can pull shoulder forward giving you lack of headspace issues all over again.

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the expander rod/decapping pin will cause issues if set to high or to low, It does need to be there to size the inside of the case.

If set to low it will bottom out inside the case

If set to high it will jam the die as its trying to size and expand the neck at the same time...

The lee die expander is higher then others... it needs to be set so the pin just pops the primer. This can be set by loosening the nut that locks the pin then sitting the shell holder up to the die and looking in the slot the case slides in the pin should be just longer than the gap (sits just longer than the gap so the pin is in the hole of the shell holder) there are measurements on the instructions but if you do it that way it works with any die setup