Checking case wall runout...

M

milanuk

New member
Looking for input from people who do use a concentricity gauge such as a NECO, RCBS Casemaster, or other home-brew devices to check case wall runout. I'm attempting to do same with my NECO gauge, but I'm finding the directions a little... off, mainly because the test indicator pictured in the destructions is a different model/configuration than what I have (mine is newer), and basically, I can't really make it work that way without breaking/bending something.

One person I've spoken with uses theirs to 'spin' the cases and get a running TIR number; despite having several conversations w/ them about it I can't seem to manage the same technique with any degree of accuracy (needle swinging all over the place). I've tried marking four cardinal points on the case body and taking static readings... results seem to vary wildly there as well: one batch (fireformed, but cleaned inside and out) showed very little variation, another batch (virgin, but same lot) shows 2-3x as much runout.

Getting a little frustrated here...

TIA,

Monte
 
OK, first of all..... How caqn you expect to get ANY meaningful readouts from virgin brass?? The stuff's squeezed out in a hammermill! You might as well measure a turd.

Secondly, getting good readings down inside the case is hard. I've had to modify both of my "concentricity" and runout measuring devices.

All of this is why I have my chambers cut at .005-,007 oversized :) then you just look at them.

al
 
Hmmm... so I'm supposed to fire-form each of a thousand pieces of brass before I can get any useful measurements off of them? Thickness variations should be there before as well as after, no?

I polished the ever living heck out of the tip, got rid of all the machining marks from forming, as well as the sharp edges/points. Still had issues. Finally ended up running the case mouths over a mandrel, actually the floating carbide expander ball from my die so the case mouths would consistently ride on the same level of the stepped cone and things magically got a lot better ;)
 
milanuk said:
Hmmm... so I'm supposed to fire-form each of a thousand pieces of brass before I can get any useful measurements off of them? QUOTE]


Wellll, yeahhhhh

sorry, but we're talking about ACCURACY, not bulk loading and how to make it work.

al
Click to expand...
 
alinwa said:
milanuk said:
Hmmm... so I'm supposed to fire-form each of a thousand pieces of brass before I can get any useful measurements off of them?
Click to expand...


Wellll, yeahhhhh

sorry, but we're talking about ACCURACY, not bulk loading and how to make it work.

al
Click to expand...

So am I.

2007 I loaded up 600 rounds of precision .308 Win to take to Raton, NM for the back-to-back Spirit of America Fullbore Championship, and the U.S. FCNC. Between one thing and another - sight in for the radically different local conditions, practice day, and lending my gun (with ammo) to other people (including team mates) whose guns had issues... I came home with exactly eleven rounds.

2008 I loaded up 500rds for US FCNC... Open practice day, squadded practice day, three days of individuals, plus team matches. I came home with a bit more than the year before, but I figure its a matter of 'have and not want'.

I'm finishing up prepping, fire-forming and final loading of the better part of 900rds of .308 Win to take to Bisley for the FCWC. If you think I'm not loading for 'accuracy', you better think again. Every friggin' round is full-meal-deal match prepped, including weighed out to the limits of my Acculab VIC-123. Large lots allow us some latitude in terms of sorting/batching brass, while allowing enough to get through the average 3-4 day state/regional LR championship plus sighters, plus team matches, etc. 250rds in such a weekend is not unusual, and nearly *everybody* pre-loads.

The brass I'm sorting *now* is for use in 'the other barrel' that will be seeing the bulk of the use for the rest of the 2009 season, as the 900rds above has to be shipped off in advance to get through customs and all. Not *all* of it is earmarked for extra-special match use on the 1k yard line... which is why I'm trying to do some kind of meaningful sorting/culling to separate the stuff I use for load development and practice and sighters from the 'serious' match ammo. Measuring case wall runout is something new for me, and I may or may not stick with it depending on whether I can make it work, and what the results are.

So... when/if you can step down off your high horse, any help you might be able to render would much appreciated.
 
milanuk said:
So am I.

2007 I loaded up 600 rounds of precision .308 Win to take to Raton........

2008 I loaded up 500rds for US FCNC... ....

I'm finishing up prepping, fire-forming and final loading ........ If you think I'm not loading for 'accuracy', you better think again. Every friggin' round is .......
So... when/if you can step down off your high horse, any help you might be able to render would much appreciated.
Click to expand...


Huhh??

My HIGH HORSE????

Yeahhh, good luck wi'dat.

al
 
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