Necking down problems...

[Hapnin]

I'm trying to neck some 6.8 spc cases down to 6mm for an AR15 project. I'm using Silver State small primer brass and running it through a Redding FL die supplied specifically for this chambering,6WOA). I'm using Imperial and I tried some "One Shot" just to compare. This case necks are coming out " egg shaped" and runout is running .015+. The case necks/ mouths look horrible. I've ran some through the die without the expander and runout is at .003 and under but the neck is way too tight for a bullet. I'm thinking the neck portion of the die is way too small. The expander mics .241".
I've had a few necks crack after running them through the die twice.

This is my first try at "necking down" cases and I'm not sure which way to go from here. Any help would be greatly appreciated.

 

[race4hills]

You will need to neck it down in steps. Try going from .277" to .264" then down to .257" and then down to .243". If you get a Redding S bushing neck sizer die then get the different bushinshing for each step.

 

[Hapnin]

That might be the way I end up having to do it. It's my understanding though that most people that load this round are just running it through this one die and loading em up. I'll do some more checking though to be sure.

The FL die I have now is a Redding and all my others are Forsters. I'm also using the Forster Coax press. I put a Forster lock ring on the Redding die. Are there any differences between the 2 brands that might be causing the Redding to be " out of line " in the Forster press? I wouldn't have thought so, but I'm questioning everything at this point.

Thanks.

 

[cliffe]

first thing to do would be take the expander-decapping piece out of the die and try just down sizing the neck. then after you get close to the desired neck size use the expander. good luck cliffe

 

[Winchester69]

Are the case mouths squared before the attempted case forming? I'm thinking that the compliance afforded by the Forster shellholder may be allowing the die to mis-center on the case mouth if the mouths are not square. The egg-shape you describe would result from such a misalignment. Just a curiosity.
.

 

[Hapnin]

I'm gonna try to neck it down in steps with a bushing die. What do ya think...the Redding s-type neck or FL die? Plan to do it without the expander until I get ready to go to the 6mm size then put the expander back in. I think that right now, trying to neck them down from 6.8mm to 6mm...the expander is having too hard of a time coming back through the neck on the upstroke. This is causing the case to be "lifted" in the jaws of the Forster press and the case is coming out of the die at a slight angle. The neck portion of the die I have may indeed be too small but the S-type die would solve this for now. This is for an AR project so I'll have to FL size the cases, therefore I'll probably go with the S-type FL die for the 6.8 SPC and just buy some bushings to neck it down to the 6mm.
Unless anyone has any better ideas...this is how I plan to procede.

As an aside. The case mouths on the new cases were a little dinged up when I got them so I used a Siclair neck turning mandrel to straighten them before trying to resize them. After I started having my current problem, I tried some new cases that I hadn't "expanded/ straightened" and I got the exact same results as before.
Thanks again for all the help and suggestions.

 

[number40Fan]

What is the case OAL supposed to be and what is it after running through the sizer for the first time? I am thinking you might need to trim the case before sizing.

 

[Hapnin]

Case length was good before and after sizing.

One of the reasons I think the neck of the die is too small is that after running a case through, I can't run the same case back through again. I mean the expander won't go through the hole that it just came out of. I guess this could also mean that the neck walls are too thick and there is too much spring back. I'm not set up to neck turn and would like to avoid it if possible.

Any more ideas?

Thanks.

 

[rstreich]

Lynn,

The Wilson bushings work quite a bit better for big sizing steps than the Redding bushings--a larger chamfer apparently--but I've taken down 222 Rem brass down to 17 caliber in ~.015" increments with Redding bushings without any problems. But then, I did put a decent chamfer on the case mouth beforehand and took it slow on the down stroke to make sure that the cases centered up on the bushing--that seemed to be the trickiest bit.

This might be an apples an oranges comparison, however, since your experiences are probably with cases that hold enough powder to fill a whole box of the cases I'm messing with.

Hapnin,

I wouldn't worry about runout until you've actually fireformed the cases. I'd also yank the expander balls--they just complicate the issue. Get a K&M expander like Lynn suggests.

The problem with the non-bushing FL dies is that, as you found, is that they size the neck way down and then rely on the expander ball to open the neck back up. It adds a lot of wear and tear on your brass. And bushing dies don't usually work for forming cases unless they're modified--the bushings don't size the whole neck. You can either have someone open up a bushing die for you or you could get Jim Carstensen,JLC Precision) to modify a Forster FL die for you to take bushings. He'll make sure that it'll size the entire neck. This way you wouldn't need to buy the form dies.

Generally, seater dies,non-micrometer type) seem to be the best next-to-last step. With a modified bushing die, your steps could be something like:

1) Size with a ~.292" Wilson bushing,depending on your neck thickness).
2) Run it through your seater die with the seating stem removed.
3) Size with a ~.272" Wilson bushing,again depending on your neck thickness and the amount of neck tension that you want).

You should also put a chamfer on your cases before you start. Maybe you have and I just can't see it in the photos.

robert

 

[rstreich]

Lynn,

I'm having a bit of trouble reconciling a couple of statements in your post:

I'm a tight wad...RWS 375 brass....

Sorry, couldn't resist