308 to 708

[jsthntn247]

I'm wanting to use 308 Palma brass in my 7-08. I took my RCBS fl 7-08 die and screwed it in the press to the same setting I use to FL resize the 7-08 Nosler brass I'm currently using in this gun. I then took two new pieces of 308 Palma brass and ran it through the die. This is what came out. Why the false shoulder if both use the same headspace gauge?

 

[CaptainMal]

Your picture and description is making it hard to answer.

Why would you change the headspace of the 308 case so dramatically? Looking at the picture makes no sense. They are two totally different length cases. That shoulder should start at the same length or are you holding hem different?

Cranking down dies without using the tools to measure headspace is meaningless. Dies can vary and the settings in a particular press can vary.

You need a headspace measure on the 7mm-08. Then move the die so there is no change in headspace, just a length change in the sized neck. See what length is correct, adjust to that and it should be good. I also would anneal after making the change.

Shoot one in the 7mm-08 chamber, measure that headspace and set the die correctly for that particular chamber as it may be different than the 308 chamber you have.

 

[jsthntn247]

I edited the first post in case it was confusing. Yes the two pieces are held differently, they are identical new pieces of neck turned Lapua ran through a 7-08 die.

 

[bobm]

Your problem is a simple one. You are not actually FL sizing the case. Screw the die in more until you make light shoulder contact. That "step" will go away.

 

[kmon]

The times I have used 308 brass for the 7mm08 the necks had to be turned since they were too thick after sizing. Check that as well as trimming case length.

The above post is also correct measure for headspace, doesn't look from the picture that the die was setup quite right for making the conversion to me.

 

[savagedasher]

Most Fl dies have to touch the shell holder. or close for normal head space. Yours isn't close. Larry

 

[jsthntn247]

Most Fl dies have to touch the shell holder. or close for normal head space. Yours isn't close. Larry

That is touching the shell holder plus 1/16th turn. It's camming over on the shell holder.

 

[savagedasher]

Is it a bushing die? The case in the left looks like it could be touching on the shoulder. Larry

 

[jsthntn247]

It's a full length die non bushing.

 

[savagedasher]

Your brass should check around 1.630 for the die to be correct. Larry

 

[bobm]

Questions: You are using a standard RCBS full length die? It is touching the shell holder PLUS a 1/16th turn at top of ram stroke?? (not good, either.) Your cases look like that under those conditions? Something ain't right. Could those .308 cases have shoulders set back too far? Do you have a way to measure the 1.630 head to shoulder length on the .308 brass? Show us a side by side picture of a 7-08 case fired in your rifle and an unsized Palma case.

 

[Terry_M]

I only use LC 308 brass for making 7-08 and have never had that step in my brass when sized. I've only done a couple thousand brass so I don't have the experience of several of the other shooters here, but to me it looks like the brass is not reaching the shoulder in your 7-08 die. It appears you got a bad die. Do you have access to another 7-08 fl die?

 

[bobm]

Pictured are a .308...7-08...and a standard 1.630 go headspace gage. I made a bushing tool to measure shoulder lengths when setting up dies for bumping shoulders and fitting chambers to my liking. I machined it to read 1.630 using calipers over the go gage, then subtract the .500 length of the bushing. The groove is a visual aid for same direction orientation each use.

Is it me or do those two .308's in the OP's picture look to have longer necks hence pushed back shoulders?

 

[jsthntn247]

Pictured are a .308...7-08...and a standard 1.630 go headspace gage. I made a bushing tool to measure shoulder lengths when setting up dies for bumping shoulders and fitting chambers to my liking. I machined it to read 1.630 using calipers over the go gage, then subtract the .500 length of the bushing. The groove is a visual aid for same direction orientation each use.

Is it me or do those two .308's in the OP's picture look to have longer necks hence pushed back shoulders?

Looks to me like the neck on the 7-08 in your pic stops higher than the .308 by about the same amount as my die stoped reducing the neck as well. When I get home I'm going to measure the headspace on some fired 7-08 cases I have and run the 308 brass up in the die to the same headspace and see if that sizes more of the neck.

 

[bobm]

Interesting, I like plenty of others here turn .308 into 7-08 all the time. Mine do not have that step and come out looking like 7-08's ready to load. Gotta see that side by side picture I mentioned.

I just now resized a once fired RP .308 to 7-08 in a full length standard Redding die. Looks very much like the once fired WW on the right. Left is a once fired RP .308. The two 7-08's measure at 1.632 shoulder length with my little bushing. The before length of the .308 was 1.635. There is a .020 gap between the shell holder and the die face at top ram stroke of my Ultramag press.

 

[bobm]

Oh crap. : I just re read and saw NECK TURNED .308 Lapua brass PRIOR to sizing in a 7-08 FL die. That is extra brass that was formally in the .308 shoulder now in the newly formed 7mm neck. You now have a neck with two different wall thicknesses.

 

[dkhunt14]

Oh crap. : I just re read and saw NECK TURNED .308 Lapua brass PRIOR to sizing in a 7-08 FL die. That is extra brass that was formally in the .308 shoulder now in the newly formed 7mm neck. You now have a neck with two different wall thicknesses.

No if you neck turned to the shoulder junction of the 308 when fireformed the turned part will be in the shoulder. It is just like when you turn a 6BR case and form into a Dasher. I stop 1/16 shy of junction and when formed the turned part ends up in the middle of the shoulder. The Dasher neck is shorter then the 6 BR just like the 308 forming into 7MM-08. I believe he also used a bushing die. Matt

 

[bheadboy]

+1 Bobm

I have done hundred's of cases including GI 308 to 7-08 using RCBS FL and never had the problem.

what is the fired or unfired 308 base to shoulder length vs your 7-08 base to shoulder, fired, they should be the same, if not then you have other problems

Bob

 

[bobm]

I had to check this out by this method as I do not turn necks. I black inked and scribed a groove into .308 cases at the neck-shoulder junction. I then ran them up the 7-08 FL die. You are correct, the scribe and ink are into the new shoulder. I stand corrected.

What if only half the neck length was turned? In the original picture is that step at the stop point of the neck turn cut? I inked only half the .308 neck. The picture seems to support only half or more of the neck length is turned before run into the FL die..

 

[jsthntn247]

I looked at them again and mine look different because the neck was already turned. The neck of a 308 does become part of the shoulder of the 7-08. So, what should the process be for new brass? Size through a 7-08 die, turn neck only TO the new shoulder, fireform, final turn and go slightly into the now formed shoulder as usual?