Thread: Concentricy Gauge - Southland??

Hello Folks

I'm still having issues with my 6mm Crudmore. Its not something I've every worried about before but with some "unproven" dies and very long snooty Sierra 110's I'd like to check a few reloads.

So anybody in Southland with a concentricty gauge I could run a few rounds over??

Thanks
Foster

Not sure but would be surprised (guess it depends if it's your local regular gun shop) if custom guns dont have one you could use...

Well Greg (at Custom Guns) did have one and a sorry tale it told, heaps of run-out (7 or 8 thou on some) at the case neck where it joins the shoulder - now to pin down whats causing that. Its worse in the new cases, once fired ones that have been resized were showing a lot less runout.

Thoughts on possible causes are welcome !!

If you get stuck and its pissing you off send me a pm
I've got a KM neck turning tool which will solve 99% of the concentricity issues. Youd have to get a 6mm pilot from Workshop Innovation (aka Good bastard), but happy to lend it to you

Darn it wish I'd seen the messages day earlier!!!

I could've bought my one down that I haven't even used for you to borrow.

Either way you're more than welcome to borrow it

try this simple method....when you are seating projectiles..start it into case mouth then rotate half way round and complete stroke..... I KNOW it works as have had much cleaverer folks than myself scoff at idea then eat humble pie afterwards.....

Yes the turning thing does work MD. I think in my case I have been using a shell holder half full of crap, so the case is not going fully into "battery". Have a new shell holder and have just run some dummy rounds in new brass - only 2 and half thou max run-out. Now to try some live rounds!

Definitely works Mick - no question.
ALWAYS use that technique, usually a third of a turn per stroke.........(sounds a bit dodgy ah)

There are several reasons why you may be getting excessive runout. The most common cause is when using a standard type die with an expander ball on the decapping shaft that is out of alignment with the axis of the die body. Try loosing off the lock nut and let the shaft float. Also, if you are using that type of die, which is the most common, try smoothing the expander ball radius (not the circumference) on the top part of the ball that first enters the resized neck. You can do this by removing the expander, decapping shaft and using a drill and some wet and dry paper.

I use Wilson hand dies with an arbor press for my 6.5 CM and average about .001" runout with unturned necks on Lapua and Peterson brass.

Further to 10-Ring - where I still use dies with an expander on the decapping shaft, I put an O ring between the decapping shaft lock nut and the die body and just ever so slightly snug it. Some dies are crap in that if you rotate the decapping rod in the die the decapping pin draws an egg shaped circle. Rotate until the decapping pin is as close to the central as possible.
I have seen some mates' dies with the decapping pin so badly centered it is amazing the pin finds the flash hole.

And re turning, in my last build, a 308 FTR, I decided not to neck turn. Using Peterson and Lapua Palma I'm getting less than 1 thou RO. And, the Peterson and Lapua brass is not perfect having the usual classic 0.2 thou seam. Normally I would anguish over that and skim neck turn.

Like 10-Ring I use a Wilson inline seater. Mine was purchased as a blank and then cut with the same reamer used to chamber my rifle.

How do you "float" the expander in a Hornady die with the "zip" expander. I've tried "floating" the whole die with an O-ring, and that seems to have worked to "remediate" my old brass. I'm pretty sure the issues are primarily down to my technique and processes, but I must have gotten away with a hell of a lot in the past . . . .

Originally Posted by Tentman

I must have gotten away with a hell of a lot in the past . . . .

True
You are still alive to tell the tale !

Originally Posted by Tentman

How do you "float" the expander in a Hornady die with the "zip" expander. I've tried "floating" the whole die with an O-ring, and that seems to have worked to "remediate" my old brass. I'm pretty sure the issues are primarily down to my technique and processes, but I must have gotten away with a hell of a lot in the past . . . .

I just "floated" all my Hornady stuff away years ago. But to be fair I had their earlier dies that didn't have the later mod to the spindle to prevent it slipping.