Sure learned stuff from all of this - for me I would look into periodic calibrations of my gear that determines runout by using a surface with zero known run out; anything less than .001 might be caused by a surface irregularity. Should I need to reduce dimensions of some hard steel object, I would also check out precise grinding techniques vs. lathe turning some super hard steel object to skim off perhaps .007 of surface. I would also be curious about acceptable or desirable headspace tolerances used by bench rest wizards; I have been told more than once that just a tiny bit more headspace than none is desirable.
Runout caused by a bushing?? - Solved
- Thread starter dstoenner
- Start date
dstoenner
Silver $$ Contributor
I didn’t take anything by your post. I thought I had covered that in my original post but it never hurts to ask about the basics. Aren’t we all guilty of missing something basic every now and then.
Thanks for making me think
David
dstoenner
Silver $$ Contributor
Yes you are right. I was guilty of taking what I was doing for granted without checking the final output. I didn’t QC my own stuff. I had figured out “my process” and figured as long as I did it all the same I would get the same results. If I had checked the runout of my output when I changed that bushing it would have been obvious and I wouldn’t have had maybe 250 6br cases out of whack
Lessened learned
David
When I find myself with a die that doesn't bump the shoulder back far enough, I just set up the shell holder on my surface grinder and take a few thou off, works fine. I also use the Redding sets for all of my bottleneck cartridges.
Carbide tooling can be used to cut a die, but you need to make a holder for the die to be held in the lathe chuck. I do this by drilling and tapping (or single pointing) a piece of 1-1/2 or 2" aluminum round stock to 7/8-14 and screwing in the die and using the lock ring to lock it in place. Get a nice square cut that way.
However it is done, the surfaces need to be square to the center-line and flat. An angled surface on the die or shell holder is not a good condition.
Carbide tooling can be used to cut a die, but you need to make a holder for the die to be held in the lathe chuck. I do this by drilling and tapping (or single pointing) a piece of 1-1/2 or 2" aluminum round stock to 7/8-14 and screwing in the die and using the lock ring to lock it in place. Get a nice square cut that way.
However it is done, the surfaces need to be square to the center-line and flat. An angled surface on the die or shell holder is not a good condition.
Take some fine wet and dry sand paper and lay it on a piece of plate glass the size of the sheet of sand paper. Wet the glass to keep the paper from moving and apply water or light oil to the sand paper. Now lap the top of the shell holder using a figure eight motion until the desired amount is removed.
A shell holder is much cheaper than a sizing die and you only need a flat surface to lap a shell holder. And remember brass spring back varies with brands and age of the cases, so do not be hesitate to lap a smidgen more off the top of the shell holder.
I just chuck up a shell holder in the lathe and turn .010” off the TOP once the needed amount is found. Then simply adjust the die until the desired bump is given.
How I determine what needs to change is by using feeler gauges under the case head with the expander/de-capper rod removed.
Cheers.
How I determine what needs to change is by using feeler gauges under the case head with the expander/de-capper rod removed.
Cheers.
Good process, not having a lathe but having a Dremel with a diamond wheel and a set of feeler gauges I do about the same. I am working on a process to spin a shell holder using a mandrel held in my cordless so I can hold the spinning shell holder against a diamond sharpening stone ( medium grit). The Dremel makes the shell holders look sort of distressed.
Help me out. I assume you mean .002 smaller than the outside diameter of the brass neck with a seated round in place for the die and .001 larger than the neck (of what? the bullet diameter?) for the expander, correct?
Last edited:
Rwfish
Silver $$ Contributor
Not sure you’ll get direct feedback from a 5year old comment??
Thanks - didn't catch that.
6MMsteve
Gold $$ Contributor
use bullet dia to determine your neck tension if .264 then use .262 o r .2625 .263 ect mandrel to get the feel or the accuracy of what the barrel likes if that's what ur askin
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