Runout
- Thread starter shinny
- Start date
Dick Grosbier
Club Coordinator
Is there a accecptable amount of runout for case necks and loaed rounds when mesaured on the bullet?
.0001" would probably be very acceptable.
Dick
jackie schmidt
New member
Acceptable Runnout
We would all like to see "zero", but what I settle for is about .001. My 6PPC and 30BR dies will consistantly hit that mark, I would rather not straighten them if at all possible. I think straightenning rounds actually might do more harm than good because it compromises the neck tension. Consistant neck tension just might be more important in solving the "accuracy equation" than round straightness.
For what it is worth, many of us have sat down with our Rail Guns on good days and seen for ourselves just what is tolerable. I have shot 10 shot groups with rounds that ran out in the .003 range, and the groups were not much different from the groups that had rounds where every loaded case measured .001 or less.
Doesn't prove much, but what we all try to do is strive to get everything as close as possible, if for any other reason, peace of mind...........jackie
We would all like to see "zero", but what I settle for is about .001. My 6PPC and 30BR dies will consistantly hit that mark, I would rather not straighten them if at all possible. I think straightenning rounds actually might do more harm than good because it compromises the neck tension. Consistant neck tension just might be more important in solving the "accuracy equation" than round straightness.
For what it is worth, many of us have sat down with our Rail Guns on good days and seen for ourselves just what is tolerable. I have shot 10 shot groups with rounds that ran out in the .003 range, and the groups were not much different from the groups that had rounds where every loaded case measured .001 or less.
Doesn't prove much, but what we all try to do is strive to get everything as close as possible, if for any other reason, peace of mind...........jackie
My indicator won't read .0001 at best .0005
Boyd Allen
Active member
The number depends on how the loaded round is supported and where the indicator is placed. if we are not measuring using the same setup, we are not comparing "apples to apples". If we are supporting on the body, just in front of where the pressure expansion near the head starts, and just back of the shoulder, where does your indicator touch the bullet?
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Boyd, I'm using a Sinclair tool and case is supported where you indicated. Indicator tip contacts the bullet just ahead of where it exits the neck and is certainally on the bearing surface i.e. .308
jackie schmidt
New member
Adding to What Boyd Said
If you use a checker that supports the bullet at the point, and the case at the rear, that is like putting something between centers.
If you run the case body in V-Blocks, and check the tip of the bullet, that is like hanging it out in a steady rest.
While you might get different set of numbers, the idea is to ascertain if there is appreciable run-out.
I use one of those little things that Lester Bruno sells. It simulates the round being between centers, and it does give you a good idea how bad, or good, things are. It also offers a very easy way to straighten those that run out if you choose to do so.
I would rather not get into the arguement as to whichmethodis better. As with many things, using common sense with either goes a long way......jackie
If you use a checker that supports the bullet at the point, and the case at the rear, that is like putting something between centers.
If you run the case body in V-Blocks, and check the tip of the bullet, that is like hanging it out in a steady rest.
While you might get different set of numbers, the idea is to ascertain if there is appreciable run-out.
I use one of those little things that Lester Bruno sells. It simulates the round being between centers, and it does give you a good idea how bad, or good, things are. It also offers a very easy way to straighten those that run out if you choose to do so.
I would rather not get into the arguement as to whichmethodis better. As with many things, using common sense with either goes a long way......jackie
Boyd Allen
Active member
If I remeber correctly Dick Wright wrote it up in PS a long time ago. My memory of that article is that it is a very well made piece, that is easy to use. Continuing on what Jackie said, I have an old Sinclair that is based on three steel blocks on a common shaft, with bearing balls supporting the case. It is my favorite for case work, and for a quick evaluation of loaded rounds. I also have an H & H that supports on the nose of the bullet and the back of the case. It is easy to straighten with, can be used with a variety of calibers, and is built as sturdily as a brick (but a lot better looking). I wouldn't say that one way of supporting or point of measuring is better, just that since they effect the outcome, it is good to be on the same page.
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JerrySharrett
Senile Member
Are you asking about out-of-roundness of the case neck or runout of the bullet point somewhere along the bullet body?
I know Bud Welsh but I don't remember what his concentricity checker looks like.
T
tenring
Guest
If the dial indicator is on the neck (unloaded round), you roll it and concentricity is excessive, can you be certain it is in the neck? Isn't it possible that the case is out of round further back on the body?
Boyd Allen
Active member
That is the reason that the fellow that designed and builds the H & H believes that supporting a loaded round at the nose of the bullet and in front of the case head is a superior method for that particular task.
This looks like a possable long thread on case to neck run out.
I'm sure it's been gone into in depth at some time.
I remember back when with case neck straight tools and the like.
I think it might even go to the extreams.
Lets look
case actual concentric.
They make tools to check the actual wall thickness on cases.
I guess all you do is sort the cases maybe theres a fix.
Next would be the sizing die and run out on the press .
Maybe a straight line sizer and an arbor press for this.
Next would be the seater die and a straight line seater die set up.
The all important neck turning tool also.
So what are the opinions?
Does this mean
the following?
I a sizing die made with your reamer reamed to a very close tolerance?
2 a seater die made with your reamer to the same close tolerance?
3 a tool to check the inside of the case for wall thickness?
4 Of couse a really good neck turning tool.
5 A decent arbor press.
6 the sinclair or other tool to check the runout on a loaded round?
Finally just how much is enough or acceptable?
.
I'm sure it's been gone into in depth at some time.
I remember back when with case neck straight tools and the like.
I think it might even go to the extreams.
Lets look
case actual concentric.
They make tools to check the actual wall thickness on cases.
I guess all you do is sort the cases maybe theres a fix.
Next would be the sizing die and run out on the press .
Maybe a straight line sizer and an arbor press for this.
Next would be the seater die and a straight line seater die set up.
The all important neck turning tool also.
So what are the opinions?
Does this mean
the following?
I a sizing die made with your reamer reamed to a very close tolerance?
2 a seater die made with your reamer to the same close tolerance?
3 a tool to check the inside of the case for wall thickness?
4 Of couse a really good neck turning tool.
5 A decent arbor press.
6 the sinclair or other tool to check the runout on a loaded round?
Finally just how much is enough or acceptable?
.
O
OldPPC
Guest
I looked at Bruno's site and I can't find anything that, to my eye, matches your description. Do you have a better description of what the "little thing" is?
Pete Wass
Well-known member
Have you looked at the Hnew Horniday?
There is an article in a recent magazine on the new Horniday. It looks interesting. This is an area I haven't delved into. i think it may bear some looking into but haven't found a device yet I thought was accurate enough and easy enough to use.
There is an article in a recent magazine on the new Horniday. It looks interesting. This is an area I haven't delved into. i think it may bear some looking into but haven't found a device yet I thought was accurate enough and easy enough to use.
Boyd Allen
Active member
Pete,
Have you tried one of these?
http://benchrest.com/hnh/index.htm
I have one, and have used it at a match with no time issue. It is easy to use and with a little practice you can quickly straighten Benchrest ammunition to three quarters of a thousandth.
Have you tried one of these?
http://benchrest.com/hnh/index.htm
I have one, and have used it at a match with no time issue. It is easy to use and with a little practice you can quickly straighten Benchrest ammunition to three quarters of a thousandth.