Help me choose a neck bushing for my Redding Die

[dmproske]

I am loading for a Remington Sendero in .300 RUM. Factory barrel. I started with a RCBS neck size set and am having problems getting under 1.5" at 100

I decided to get the best dies possible to get that problem out of the equation. I purchased a set of Redding Type S match bushing neck die set with the body die in it.

When I ordered the dies I selected a .334 bushing. I think that is where I screwed up, not sure what I measured that day.

Once fired cases out of my rifle have less than .001 variation as measured by my Sinclair concentricity gauge.

Today I used the dies for the first time. I sized three of the once fired cases and wound up with .004-.007 neck runout!!

I thought maybe I got a too small bushing and measured two boxes of factory ammo. Once box measured .338-.339 outside neck diameter. The other box of a different brand measured .336-.338 outside neck diameter.

I measured neck thickness of a handful of my cases with my RCBS caliper and came up with .0015-.0018.

Using this information, it looks like I might need a little larger bushing like say a .337.


Will using a too small bushing cause that much neck runout?

 

[Kevin Cram]

It would be a good idea to skin turn your necks. You don't have to get them to clean up 100% but 80% would be suffucient, just enough to knock off the high spots. From there use a ball mic to measure the wall thickness for unniformity. A set of calipers has a flat on the jaws and is giving you a false reading. You'll probably end up with .014 .015 neck thickness. Your .334 bushing should work but I would try a .336 myself. I also de-prime my cases with a seperate die and remove the threaded rod that holds the de-capping pin in my type S dies. It shouldn't be causing it but maybe the sizing ball that holds the de-capping pin is too large and double sizing the neck crooked, once with the bushing and once again on the way out with the sizing ball. I have a Type S for my .308 Win and I had to use a smaller sizing ball becasue it was making contact with the inside of the neck on the way out and giving me a larger than desired neck.

 

[dmproske]

I have a larger bushing and some neck turning tools on order. What I do not get is that the necks are true when coming out of the rifle. As in less than .001 neck runout.

After sizing I am getting .003-.004 neck runout. The dies came with two seperate sizing balls. I am using the smaller one and do not feel it hitting the neck.

 

[woods]

Hey dm

The necks should be true when coming out of your rifle. The firing has pushed the neck brass to your chamber and almost all chambers are cut true.

IMO a bushing die should not be used with and expander ball at all. The reason you are using the bushing is to set you outside neck diameter to a specific diameter. If you then run an expander back through it you might as well be using a regular full length die.

Also the bushing dies work best with a consistant neck thickness so outside neck turning will help. If you turn your brass down to it's lowest thickness of .015" then the math would be: .308" (caliber) + .015" + .015" = .338" which should be the outside diameter of your neck after turning the brass and loading a bullet. Now it will depend upon how much bullet grip you want as to what bushing you need. A .334" bushing will give you .004" of bullet grip. That is a little stiff and I prefer .002" for ease of seating and not to cause runout.

Another thing you need to realize is that with a neck thickness variation of .015" to .018", when you size with a bushing then you will be pushing that variation to the inside of the neck. Since neck thickness variations will usually be thin on one side and thick on the other, seating a bullet with the variations on the inside will tilt the bullet and lead to lots of runout.

Turn the necks to .015" and get a .336" bushing.

 

[trueblue]

dmproske,

You got great advice from both Kevin and Woods.
+1 on cleaning up the necks to 0.015 thickness, and going with the .336 bushing without the expander ball.

 

[dmproske]

Thank you for the replies. A few days ago I orderd some neck turning tools and a .336 and .337 bushing.

My type s die set came with two different size exander balls that also hold the decapping pin. I use this die to decap as well. The smaller ball is so small I believe it does not touch the neck at all. I am fully aware of the problems that expander balls cause and that bushing dies should not use them.

That being said I have a few more questions....

1. Does redding offer a decapping assembly for their dies that have no expander ball at all?...do i can totally rule that out.

2. Should I neck turn before or after sizing fired brass?

3. What about fresh new brass? I have a 500 count box of new brass that has some very visually crooked and out of round necks. How do I turn these? I may have to run them through a expander ball to get them in the ball park enough to see what I have. Some of the necks are almost square shaped
I hate to cull them out. .300 ultra brass is too **** expensive to do that.

 

[trueblue]

I full length resize new or once fired brass, then neck turn . Do your neck turning before you trim, as trimming leaves an edge on the inside of the neck. I use the Sinclair neck turning tools N-1000 I believe it is called. You will need an expander mandrel and a turning mandrel along with a die body to hold the mandrels. Then just adjust the cutting depth on the cutting tool to shave approximately 80% of the case neck to clean off the high spots.

 

[woods]

That being said I have a few more questions....

1. Does redding offer a decapping assembly for their dies that have no expander ball at all?...do i can totally rule that out.

2. Should I neck turn before or after sizing fired brass?

3. What about fresh new brass? I have a 500 count box of new brass that has some very visually crooked and out of round necks. How do I turn these? I may have to run them through a expander ball to get them in the ball park enough to see what I have. Some of the necks are almost square shaped
I hate to cull them out. .300 ultra brass is too **** expensive to do that.

1. Get a Universal DeCapper, works for all calibers and doesn't complicate the feel of the sizing operation

2. You will have to have a tight fit on the neck turning mandrel. With fired brass your inside neck diameter will be too large to get a tight fit. Depending upon your sizing die, the inside diameter of the neck after sizing may be too tight. That is why K & M (arguably the best neck turner) offers an expander as a precursor to using their neck turners in order to make the mandrel fit tight but not too tight. Personally I use a Lee Collet Neck Sizer which only sizes the neck .001" to .002" below caliber diameter and that works well with the Forster mandrels (they are very tight but workable).

3. New brass is when I outside neck turn. That is where I use the Lee Collet to straighten out the neck and prep them for turning.