6.5 SS (Sherman Shortmag)

Rich, I tried to send this via PM but it says you inbox is full.

So I took some measurements and thought I would post them before I spent much time looking for for a new RCBS FL mandrel. I measured the K&M pilots (6.5 and 7), RCBS 7SAUM FL mandrel, Whidden 6.5 SS FL mandrel and a piece of brass after necking down with the 7 SAUM FL die. It is now obvious as to why the K&M pilot won't fit into the necked down brass but what is not so obvious, to me, is why so much spring back?

7mm K&M neck pilot = .282
RCBS 7SAUM FL mandrel = .282

Necked down brass (inside) = .2805

6.5 K&M neck pilot = .262
Whidden 6.5 SS FL mandrel = .262

Is the case mouth not holding to .282 because I am necking down from 300 SAUM brass? If so, then should I perhaps order a .284 RCBS FL mandrel to account for the spring back? Am I the first one to have these issues?
 
Rich, I tried to send this via PM but it says you inbox is full.

So I took some measurements and thought I would post them before I spent much time looking for for a new RCBS FL mandrel. I measured the K&M pilots (6.5 and 7), RCBS 7SAUM FL mandrel, Whidden 6.5 SS FL mandrel and a piece of brass after necking down with the 7 SAUM FL die. It is now obvious as to why the K&M pilot won't fit into the necked down brass but what is not so obvious, to me, is why so much spring back?

7mm K&M neck pilot = .282
RCBS 7SAUM FL mandrel = .282

Necked down brass (inside) = .2805

6.5 K&M neck pilot = .262
Whidden 6.5 SS FL mandrel = .262

Is the case mouth not holding to .282 because I am necking down from 300 SAUM brass? If so, then should I perhaps order a .284 RCBS FL mandrel to account for the spring back? Am I the first one to have these issues?

I likely is the 300 brass. I forgot that was what you are using. I would just get the appropriate size expander or inside neck ream a little......
 
Just dropped off my project at the smith and ordered dies and brass. So hopefully he will be ordering the reamer for rent here in the next couple weeks. Can't wait to start loading for this 6.5 SS. I am so glad that there has been a ton of documentation from everyone on this site in particular. I'm sure I will have some questions. I've been reloading for about 12 years now but this is my first custom rifle and my first time loading a wildcat. Thank you for bringing us this cartridge and I look forward to enjoying it.
 
I think Rich sells the reamers now, and does some sort of deals on reamer & die purchases. That way, if you like the 6.5 SS, and you know your counterbore and headspace, you can use the same reamer and headspace your next barrel and still use the same brass as before. There are a few advantages to purchasing your own reamer for a cartridge you know you're going to enjoy.
 
I may have to message him and ask about that. I did see he offered reamers for sale. I hadn't considered purchasing one for myself.
Plus, with the same reamer, same headspace, and all that, you can interchange brass and stuff if you decide to build 2 or more rifles at once. You won't have to worry about keeping your brass separate for each rifle since it will all be headspace the same, and cut with the same reamer.
 
Does anyone know if the reamer for the 6.5 short mag will clean up a 6.5 prc or a 6.5x284? Or must one get a new barrel? Thanks
 
The 6.5 ss is a reality. We will see how she does when I get the dies in
 

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