Redding Neck Bushing Dies and 300 SMKs.

[warrenb]

I am trying to work out a starting size for the bushings on the Rediing neck dies. I have some once fired brass that seems a fairly consistant 15 to 16 thou at the neck wall. The die set I ordered has a body die and I don't think the bushing die comes with any bushings?

Can someone please mike a few 300 grain SMKs and give me an average?

I know there may be some variance from lot to lot. I just want to get a bushing to get started when my dies arrive.

Or is there a common bushing size that seems to be consistantly used for those shooting 338 lapua?

thanks!

 

[ben hunchak]

You measure the neck O.D. of a few loaded rounds, the bushing/s you purchase should be .001" or .002" SMALLER then your smallest O.D.

 

[warrenb]

Ben,

I only have once fired cases. The dies I have ordered (I don't have them yet) come with a body die (no neck sizing) and a bushing die (no bushing - I think).
So I have no way of loading a round that I can think of.

Hence my attempt to calculate by bullet diameter plus 2 times neck wall thickness.

I'm not expecting to get the perfect tension with the first bushing just to be able to start reloading.

thanks.

 

[rnbra-shooter]

Have you measured your neck thickness using a tubing micrometer, or have you tried to do it with calipers? Using calipers it is tricky to get a good accurate measurement, though with care and persistence you can eventually get a pretty good idea.

The diameter of the 300-SMKs is going to be much more precise than the neck wall measurements you have made. You might as well assume that they are .3380" for now.

If you have .015" thick necks, then the loaded diameter at the neck will be .015" + .338" + .015" = .368". If you have .016" necks the loaded diameter will be .370".

For the former, you'd probably want to get a .367" bushing and/or a .366" bushing. If you had to choose only one it would be better to take the smaller of the two.
For the latter, you'd probably want a .369" and .368".

Given what you know so far, you could end up needing anything from .366" to a .369".

Unfortunately bushings can be a bit costly considering what they are ($15 the last time I looked, gag), otherwise the right thing to do would be to own a whole set in .001" increments.

If you were to order a .366" and a .368", there's a pretty good chance you'd be able to make serviceable ammo with it

*****
EDIT: looks like .365-.366 is a bit of a consensus: http://www.canadiangunnutz.com/forum/showthread.php?p=6476027#post6476027

Once you get your ammo loaded, you can measure up your loaded neck diameter to figure out what you neck thickness really is. It might turn out that your neck wall thickness readings of .016" are a small bit of upward bias in measuring error due to the way the flat surface of a caliper tip touches the inside of the neck at two points rather than one

 

[warrenb]

I used a caliper so yes there is some accuracy loss. Although the conscenus posted on the other thread I guess bears up these measurements to some degree.

Thanks for your help.