RCBS neck size tension

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Viper26

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I just bought an RCBS 2-die set and I think the neck sizer is giving me too much tension.
How much neck tension is right for a mag fed bolt gun?
What's the right way to measure it?

Savage 12LRP, 260rem
New Lapua brass
Hornady 140 AMAX

If the die is too tight, can it be opened up?
thanks
 
Viper26 said:
What's the right way to measure it?
Click to expand...

The "truly" right way to measure it is with a tubing micrometer and a regular micrometer. Assuming you don't have those, this way is nearly as good:

1 - size a piece of brass
2 - as carefully as you can, measure the o.d. of the neck using your calipers
3 - seat a bullet
4 - as carefully as you can, measure the o.d. of the neck using your calipers

The difference between your readings in steps "4" and "2" are the amount of neck tension that you have. Less than 1 thou is quite light, 1-2 thou is typical, more than 2 thou is needlessly too much (it won't hurt anything, but it won't be helping anything either)
 
Thanks rnbra-shooter. That pretty much confirms what I was thinking.
A loaded cartridge is 0.292 at the mouth. A sized case is 0.282.
I guess I need another 6 or 7 thou larger. Can they be honed out to size?

rnbra-shooter said:
The "truly" right way to measure it is with a tubing micrometer and a regular micrometer. Assuming you don't have those, this way is nearly as good:

1 - size a piece of brass
2 - as carefully as you can, measure the o.d. of the neck using your calipers
3 - seat a bullet
4 - as carefully as you can, measure the o.d. of the neck using your calipers

The difference between your readings in steps "4" and "2" are the amount of neck tension that you have. Less than 1 thou is quite light, 1-2 thou is typical, more than 2 thou is needlessly too much (it won't hurt anything, but it won't be helping anything either)
Click to expand...
 
@Viper26 - doesn't your RCBS neck sizer die have an expander button? (It should; and it should measure about 0.284" or so).

If your die came with an expander button and you removed it, you should put it back in.

If you want to use your die without an expander, you could increase the size of your sizer's neck, but this is a one-way operation and if you go too far it won't be useable any more. Or if you change to a different lot of brass with thinner neck walls, it won't size your necks small enough.

Usually, if one wants to neck-size without using an expander button, you get a die set with interchangeable bushings, then choose a bushing size needed for your brass.
 
Viper26 said:
What's the best lube for the expander button?
Click to expand...

It gets pretty sticky/draggy without lube, eh?

I don't know if there is a "best"; I find lubing the inside of case mouths to be a royal P.I.T.A. (which is why I tend to use Lapua brass and a bushing die).

When I size brass where I need to use an expander button, I apply regular case lube (typically the water-soluble RCBS case lube) with a Q-tip. A light dab/sweep on the inside of every fourth or fifth case seems to be enough (did I mention it was a P.I.T.A......? )
 
I've been using the Dillon spray lube, but I see a bushing die in my near future.
I've always had the Lee Collet type before. This RCBS is new territory for me.
Thanks for the help.
 
Viper26 said:
What's the best lube for the expander button?
Click to expand...

Powdered graphite, I have a film canister 3/4 full of no. 9 lead shot I fill with the graphite. Dip the neck in and size!!!

Redding sells something similar now, but uses plastic beads, it works just as we'll if not better than the lead shot, although if you have any lube at all on the neck prior to dipping, the plastic beads will stick to the neck, inside as well.
 
I like the Hornady torpedo style expander. The RCBS tends to be sharp, and I sent the one from my .22-250 back which they replaced. Since then I have converted to the Lee collet die.
my lubing procedure is with a nylon brush and keep adding RCBS lube whenever the expansion stage gets a little sticky.
Perhaps it is time to take a shotgun shell apart to reclaim the shot and get some graphite.
 
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