Shoulder Bumping

horseman2

CGN Ultra frequent flyer
Rating - 100%
163   0   1
Location
Fraser Valley
Does a neck sizer die bump the shoulder?

While neck sizing .25-06 with the die and shell holder making contact, my readings indicated a shoulder bump of 0.001 which would be desirable.
 
It isn't meant to. Since the die doesn't support the case body the way a FL sizing die does, what you are doing essentially is crushing the case. In a FL die, when you bump the shoulder, the brass has nowhere move so it flows up the neck causing the case to grow in length.

How easily do the cases chamber after? Try pushing them in with your finger, is there resistance?. And what kind of neck runouts do you get afterwards?
 
So you're using a collet neck-sizing die? If so, it's not supposed to move the shoulder. If it is you're crushing the shoulder back and need to re-adjust your die.
The instructions with mine even has a pic of a bulged shoulder with a caption that basically says "This shouldn't happen";)
 
So you're using a collet neck-sizing die? If so, it's not supposed to move the shoulder. If it is you're crushing the shoulder back and need to re-adjust your die.
The instructions with mine even has a pic of a bulged shoulder with a caption that basically says "This shouldn't happen";)

Just a RCBS Neck sizing die. My original intention was to have all of the neck sized for outside neck reaming.

I do not have a tool to measure runout and they are currently in the tumbler.
 
Even with a regular, non-collet neck sizing die, you shouldn't be bumping the shoulder.

lol. good point.:D I was more trying to find out if he was using a neck sizer or a FL sizer adjusted for neck sizing.

So horseman, to answer your question---no, the shoulder shouldn't be getting bumped.
 
It may work, depending on your chamber and die match-up. Or, it may also cause the mushroom effect at the body-shoulder junction and give you terrible neck runouts and tight chambering. No way to know without trying...
 
Outside Neck reaming.
So I had 12 fired rounds and backed the die off. I measured everyone to the shoulder and every measurement after neck sizing shortened to the shoulder. Probably something that just happens but most of the measurements were 0.001 less and some at 0.0005 with only one reading of 0.0015.

Probably nothing to lose sleep over.
 
Last edited:
neck sizing

You will find, as in all reloading tools and components, there are variations. You need to set your die to match YOUR fired cases from YOUR chamber. The dies will almost always be shorter than the chambers, (this is so they will still do their job for a SAAMI minimum chamber) thus causing your problem of shoulder bump. Just back your die out to suit your particular needs and all will be well, needen't worry about a thou, unless you mean 10 thou.
 
Back
Top Bottom