Neck (and body) sizing - what am I doing wrong?

[Fotheringill]

Question was raised above as to how much of the neck is sized. Not all neck sizing dies with bushings will size the entire neck down to the shoulder. Redding, for example, will not.

Also- how are you measuring the run out? With what tools and how are you doing it? It might be the tool and it might be you.

 

[SGK]

I am using Redding dies and bushings and am aware there is a small portion of the neck that isn't sized. But @243winxb mentioned only sizing half the neck.

It's not the concentricity gauge (21st Century). I've measured before and after. The "after" is visible to the naked eye. No doubt I cocked them up.

 

[Fotheringill]

If it is visible, my narrow well of suggestions is empty.
Brighter folks than I are already in this thread and I suspect they will straighten out the problem (no pun intended).

 

[David101]

My 308 is a custom f class barrel the neck chamber part is 0.342. I use a 336 Redding bushing in a Redding small base body die with the neck bushing. I use the small decapping pin as to not interfere with the neck once it has been sized by the bushing. when the projectile is loaded there is a few thou neck tension and the finished round is about 0.338 at the neck.

The Lee neck die which I also use gives very similar results but is perhaps not as exact when the brass is harder. but it gives very good concentricity.

 

[dkhunt14]

What is runout on bullet with bullet seated? Matt

 

[JFrank]

My 308 is a custom f class barrel the neck chamber part is 0.342. I use a 336 Redding bushing in a Redding small base body die with the neck bushing. I use the small decapping pin as to not interfere with the neck once it has been sized by the bushing. when the projectile is loaded there is a few thou neck tension and the finished round is about 0.338 at the neck.

The Lee neck die which I also use gives very similar results but is perhaps not as exact when the brass is harder. but it gives very good concentricity.

So your brass is .030??

 

[cw308]

That is thick , I can see 12 x 2 but 15 better check again . No need to change before sizing , how are you cleaning your brass ? The bushing die didn't work for me went back to a standard RCBS Standard Full size die .

 

[SGK]

So your brass is .030??

/2 = 15 thou thick

(Not far off the high side of my PPU which is about 0.0146". Of course, he has a tighter chamber neck dimension.)

 

[SGK]

What is runout on bullet with bullet seated? Matt

I have not tried to seat a bullet in this brass yet. I basically stopped when I realised I had knocked the necks out of whack. (I had checked runout on the previous lot of loaded rounds - now fired - and it was sub 2 thou on the exposed bearing surface of the bullet.)

 

[divingin]

/2 = 15 thou thick

(Not far off the high side of my PPU which is about 0.0146". Of course, he has a tighter chamber neck dimension.)

I was using Lake City brass that was originally about the same at .015". Skimmed it down to about .0145. Near as I can tell, that was a large waste of time.

OP. have you pulled the die apart and cleaned it really well? I have a feeling the brass shavings you mentioned may be playing a part.

 

[Uncle Ed]

Buy a Forster full length die and if needed have them hone the neck of the die.

A full length die will produce less neck runout than a bushing die when reducing the neck diameter .004 or more.

I check the neck thickness variations with a Redding neck thickness gauge and subtract the thickness variation from the neck runout reading.

Below a Redding full length die with a modified Forster spindle and expander installed to reduce runout and less pull on the neck.

 

[JFrank]

You can buy all the new brands in the world but until you find out what happened , it will most likely keep happening.
We normally find that re tracing our steps leads to the place where the problem started.
You mentioned trimming the high side" that right there doesn't sound good, Redding dies are highly regarded make no mistake about that. If you listen to people on the internet, you'll be grinding or modifying next, when measuring and understanding are usually the key.