Ok so i may not be looking at this right but im sure you guys will help me out...I had a new piece of winchester brass(300WM) I put it into to RCBS consintricity(sp) gauge it was around .003 of movement. I marked what appeared to be the "high" spot with the rcbs con gauge when i put the case in the forester turner it cut the oppsite side of the "high" spot. when I measured the case it was still .003????? Im sure the answer is in front of my face but i dont get it. I suppose the consentricity gauge may not be measuring neck thickness but i would think i would show you where the thick part of the neck is. Also how is it possible to trim half the neck and get the same measurment?
-
Having trouble using the site?
Contact support
Tried neck turning and im confused......
- Thread starter AtownBcat
- Start date
Re: Tried neck turning and im confused......
What may be happening is you are measuring the banana shape of the case down its whole length at the neck with the concentricity guage and not actual neck wall thickness .
However when you neck turn you turn in line with only the neck which will most likley not be in line with the whole length of the case anyway.
The neck turners mandrel centers on just the neck diameter over it's short length nothing else.
Do your case sorting then just turn up your necks to clean up about 75% then do all your other case preperations .
Then after fireforming try them on the con guage again . You should then see a vast improvement in straightness.
If some still appear to have excessive run out then they could be the bad ones.
All new brass is slightly bent to some degree .003 is nothing in a new case .
Even a gentle size in a full length die can sometimes straighten up new cases a bit but be careful not to push the shoulder back any .
New cases stretch enough as it is.
What may be happening is you are measuring the banana shape of the case down its whole length at the neck with the concentricity guage and not actual neck wall thickness .
However when you neck turn you turn in line with only the neck which will most likley not be in line with the whole length of the case anyway.
The neck turners mandrel centers on just the neck diameter over it's short length nothing else.
Do your case sorting then just turn up your necks to clean up about 75% then do all your other case preperations .
Then after fireforming try them on the con guage again . You should then see a vast improvement in straightness.
If some still appear to have excessive run out then they could be the bad ones.
All new brass is slightly bent to some degree .003 is nothing in a new case .
Even a gentle size in a full length die can sometimes straighten up new cases a bit but be careful not to push the shoulder back any .
New cases stretch enough as it is.
Re: Tried neck turning and im confused......
place fired case on gage and see how much it runs out. I suspect you will get about zero run out, next size it and try same case again. If you get the .003" you know it is a die problem.
Some die manufacturers chamber their dies in two steps. The cut the body then they run in a neck reamer which may or may not repeat on the same center line.
About fifteen years ago in Precision Shooting a guy had a article about this and he recommended getting a 7/8" O ring at automotive parts store( about .25) and putting it under lock ring. This is to allow the die to adjust for the case coming in and sizes it straighter.
I tried it and now about all my dies have the O ring on them.
Won't cost you but .25 to find out. Oh yeah the Lee dies all have a smaller rubber O ring on them now.
You adjust your die as normal to locate shoulder about .002" off the chamber shoulder. I marked mine with a Sharpie permant marker to locate to front of tool so when you replace die later it comes back to same place.
Note: when unscrewing these dies apply torque to the nut and not the die and it shouldn't move.
place fired case on gage and see how much it runs out. I suspect you will get about zero run out, next size it and try same case again. If you get the .003" you know it is a die problem.
Some die manufacturers chamber their dies in two steps. The cut the body then they run in a neck reamer which may or may not repeat on the same center line.
About fifteen years ago in Precision Shooting a guy had a article about this and he recommended getting a 7/8" O ring at automotive parts store( about .25) and putting it under lock ring. This is to allow the die to adjust for the case coming in and sizes it straighter.
I tried it and now about all my dies have the O ring on them.
Won't cost you but .25 to find out. Oh yeah the Lee dies all have a smaller rubber O ring on them now.
You adjust your die as normal to locate shoulder about .002" off the chamber shoulder. I marked mine with a Sharpie permant marker to locate to front of tool so when you replace die later it comes back to same place.
Note: when unscrewing these dies apply torque to the nut and not the die and it shouldn't move.
Re: Tried neck turning and im confused......
If you don't know the year and make/model of car that has the right sized O-ring, you're not going to do much good at the auto store these days. The guy at the hardware store will be able to communicate much more effectively.
If you don't know the year and make/model of car that has the right sized O-ring, you're not going to do much good at the auto store these days. The guy at the hardware store will be able to communicate much more effectively.
Re: Tried neck turning and im confused......
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hummer</div><div class="ubbcode-body">getting a 7/8" O ring at automotive parts store( about .25) and putting it under lock ring. This is to allow the die to adjust for the case coming in and sizes it straighter.</div></div>
Ditto
Terry
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Hummer</div><div class="ubbcode-body">getting a 7/8" O ring at automotive parts store( about .25) and putting it under lock ring. This is to allow the die to adjust for the case coming in and sizes it straighter.</div></div>
Ditto
Terry
