First attempt at necking down 308 to 7mm08

Well guys I had a go at this and didn't have any luck.

I got a few bits of that 308 brass I've got, put a tiny bit of lube on them, and slowly pushed it into the pull length 7mm08 sizing die.

I couldn't close the bolt on my rifle with any of the necked down cases. I also noted the necked down cases are a little bit shorter than the length I normally trim too. Not being able to close the bolt is a little concerning though and I didn't want to force it obviously.


I measured the outside neck diameter of the cases:

Once fired, fully prepped 708 case:
Outer width: 7.81mm
Neck width: 0.31

Once fired, fully prepped 308 military case #1:
Outer width: 7.96mm
Neck width: 0.41

Once fired, fully prepped 308 military case #2:
Outer width: 7.99mm
Neck width: 0.44

Once fired, fully prepped 308 military case #3:
Outer width: 7.94mm
Neck width: 0.41

It's a bit weird the necked down cases are wider.

You can see the actual necks are visibly thicker on the necked down cases (to be expected I imagine... probably need to be reamed out from what I hear).
http://i1222.photobucket.com/albums/...psb42ba969.jpg

And you can see the shoulder isn't quite right (necked down case is on the left)

http://i1222.photobucket.com/albums/...psd0db4bc1.jpg

http://i1222.photobucket.com/albums/...ps072daae6.jpg

You can tell the third case is the 7mm08 one
http://i1222.photobucket.com/albums/...ps2f91e4f4.jpg

Where am I going wrong chaps?

I suspect you need to adjust your die down to compensate for the extra force required to size down.
Give one the vivid treatment and try to chamber to see where its hitting. Could be neck but more likely shoulder or body

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Quote:

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Originally Posted by veitnamcam

I suspect you need to adjust your die down to compensate for the extra force required to size down.
Give one the vivid treatment and try to chamber to see where its hitting. Could be neck but more likely shoulder or body

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I agree.

Screw the die another half turn into the press and see what happens also. You may need to go further than half a turn too...

Really need to do the vivid test to check body. Military arms can have large chambers and may need a body or small base die to get it back in size. Or if lucky and carefull may get away with it with standard fl die .

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308 will always be shorter than 7-08. What brand is the brass? Lapua? As you neck down the brass has to go somewhere. In already thick walled brass its going to increase the neck wall thickness. You may need to outside turn the brass.
I too think your FL die is not stroking the brass far enough. Don't pussy around with it either, give it a good shove in the press but try to also be consistent. Use a decent lube too. I doubt in a factory chamber it will have a tight neck but you may need to outside neck turn.

Or just give me the .308 brass. I'll take it off your hands to save you the trouble. :D

Now looking at pics on pc instead of phone the shoulder looks like at least a mm longer than the 7/08 shell, wind die down.:)

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Originally Posted by veitnamcam

Now looking at pics on pc instead of phone the shoulder looks like at least a mm longer than the 7/08 shell, wind die down.:)

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agreed

I have Hornady headspace gauge attachments, allows you to actually size the brass shoulder the same as the real 7mm08 brass. Same as what VC says with the vivid marker, just a bit more scientific like. :P
Let me know if you want to to borrow them this weekend. I'm in St Heliers.

Quote:

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Originally Posted by dogmatix

I have Hornady headspace gauge attachments, allows you to actually size the brass shoulder the same as the real 7mm08 brass. Same as what VC says with the vivid marker, just a bit more scientific like. :P
Let me know if you want to to borrow them this weekend. I'm in St Heliers.

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Thanks Dogmatix,
I'll give the vivid treatment a go and try winding my sizing die down a bit and if I'm not having any luck I'll have to get a bit more scientific like and I'll flick you a PM.

Quote:

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Originally Posted by kiwijames

308 will always be shorter than 7-08. What brand is the brass? Lapua? As you neck down the brass has to go somewhere. In already thick walled brass its going to increase the neck wall thickness. You may need to outside turn the brass.
I too think your FL die is not stroking the brass far enough. Don't pussy around with it either, give it a good shove in the press but try to also be consistent. Use a decent lube too. I doubt in a factory chamber it will have a tight neck but you may need to outside neck turn.

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It's Lake City stuff (military) that's been all prepped down to 308 specs by the guy I got it from. It's supposed to be "ready to load".

I have my die adjusted down far enough that my press touches it when it goes up. I don't think I can wind it anymore (the only adjustment on that die is the primer remover depth).

I'll have another tinker tonight and put a few more pics up.

Quote:

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Originally Posted by RimfireNZ

It's Lake City stuff (military) that's been all prepped down to 308 specs by the guy I got it from. It's supposed to be "ready to load".

I have my die adjusted down far enough that my press touches it when it goes up. I don't think I can wind it anymore (the only adjustment on that die is the primer remover depth).

I'll have another tinker tonight and put a few more pics up.

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presses generally flex a little when you have a piece of brass in there being sized so winding down more so that it bottoms out earlier can still be justified

I imported Paora a Redding 7mm08 Body die from Sinclairs, we can always nab that off him and give your brass a going over to bump the shoulder back more.

Did 100 in a Lee hand press OK,Lapua though

Quote:

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Originally Posted by RimfireNZ

It's Lake City stuff (military) that's been all prepped down to 308 specs by the guy I got it from. It's supposed to be "ready to load".

I have my die adjusted down far enough that my press touches it when it goes up. I don't think I can wind it anymore (the only adjustment on that die is the primer remover depth).

I'll have another tinker tonight and put a few more pics up.

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Just wind the die down!! Dont touch the decapper if the primers are already being removed:)

yea like HH and Wildman have said you need to wind that die down to compensate for the 'press flex'.

AS an aside what causes that ring on the case second from left in the last photo? Never seen that before

If we are lookin at the same thing its the bit of neck that is still 308 from not goin in die far enough

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when you are at full stroke on the press have a look to see if there is a gap between the shell holder and the press, need good light as shadows can hide a gap

Is the shell holder the same brand as the dies? mismatched can cause issues although most are very close in size.

that shoulder looks like it needs bumping more :) but the brass was fired in a sloppy chamber previously FL sizing may not get it back to size enough to chamber if your chamber is tight....although not that common to have that happen

Once you get empty brass fitting in the chamber check a round with a projectile seated to make sure there are no problems cambering as there will be less clearance at the neck with 308 brass and if yours is a tight neck the brass may need turning... again not often but it does happen.

If you have a case fired in your rifle and not sized, measure the neck size... the compare it to a 308 case with the pill in, it will give you an idea of clearance on the neck.

You will hit the odd stumbling block with reloading, everyone does but a bit of thought usually sorts it

Just remember people advise on here is not always going to be right as they aren't there in person to see what process you have done but usually some of the info will sort it and I agree above...... :)

Quote:

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Originally Posted by veitnamcam

If we are lookin at the same thing its the bit of neck that is still 308 from not goin in die far enough

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I think you will find even right down there is still a step as the shoulder length is different?

But yes shell holder in contact with the die is step one :)

Measure the diameter at the base of the case is also a good idea if they have been fired in another rifle.... black marker covers this too

Quote:

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Originally Posted by leathel

I think you will find even right down there is still a step as the shoulder length is different?

But yes shell holder in contact with the die is step one :)

Measure the diameter at the base of the case is also a good idea if they have been fired in another rifle.... black marker covers this too

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Yea its different 708 is shorter by 2 thou so shouldn't be that ring

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Quote:

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Originally Posted by leathel

I think you will find even right down there is still a step as the shoulder length is different?

But yes shell holder in contact with the die is step one :)

Measure the diameter at the base of the case is also a good idea if they have been fired in another rifle.... black marker covers this too

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Yeah that's what I've found. My shell holder hits the bottom of the die, I can't lower it any lower (apparently the Lee case holders are a bit deeper than standard) so I can't get the shell right up in there. The shoulders are different.

I'm gonna have to track down something that'll help me sort that shoulder out.

What brand die are you using? and what shell holder?

Quote:

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Originally Posted by RimfireNZ

Yeah that's what I've found. My shell holder hits the bottom of the die, I can't lower it any lower (apparently the Lee case holders are a bit deeper than standard) so I can't get the shell right up in there. The shoulders are different.

I'm gonna have to track down something that'll help me sort that shoulder out.

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Where in Auckland are you?

Quote:

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Originally Posted by RimfireNZ

My shell holder hits the bottom of the die, I can't lower it any lower.

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Skim a couple thou off the top of the shell-holder, or off the bottom of the FL die. Preferably the former.

Ray.

you could always trade up to a 308

Quote:

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Originally Posted by RimfireNZ

Yeah that's what I've found. My shell holder hits the bottom of the die, I can't lower it any lower (apparently the Lee case holders are a bit deeper than standard) so I can't get the shell right up in there. The shoulders are different.

I'm gonna have to track down something that'll help me sort that shoulder out.

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SO in setting up your press you have:
-Lifted the ram to full extension with the shell holder in the top
-Screwed the die in till it touches the shellholder
-Lowered the ram and then turned the die in a further half a turn or more?

Have you trimmed the case prior to sizing to 7mm08?

Quote:

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Originally Posted by Wildman

SO in setting up your press you have:
-Lifted the ram to full extension with the shell holder in the top
-Screwed the die in till it touches the shellholder
-Lowered the ram and then turned the die in a further half a turn or more?

Have you trimmed the case prior to sizing to 7mm08?

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Yes I've set up the die correctly as you mentioned above. I haven't trimmed the brass though as 308 will end up shorter once necked down.

Quote:

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Originally Posted by sako75

you could always trade up to a 308

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You mean trade down aye Sako? :P

Quote:

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Originally Posted by dogmatix

Where in Auckland are you?

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Pukekohe, but I work in the CBD

Quote:

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Originally Posted by leathel

What brand die are you using? and what shell holder?

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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.

Quote:

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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.

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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

Quote:

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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

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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...

http://i1222.photobucket.com/albums/...ps9aa24eef.png

I tried seating a round just to see what'd happen to the brass.
http://i1222.photobucket.com/albums/...ps0f753363.png

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?

Quote:

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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?

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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.

Attachment 6327

Attachment 6328

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

Quote:

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Originally Posted by veitnamcam

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

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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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