shoulder bumping

[Hoodlum]

Where do you guys measure the shoulder bump when resizing? Is it measured where the body meets the shoulder, neck meets the shoulder, the datum, or any of the above? I made a gauge comparator gauge to help measure the shoulder bump, and made the measurement point on the datum (.40") on .308win. Just making sure it's the correct point before I start using it to measure...

Hoodlum

 

[mdmp5]

Where do you guys measure the shoulder bump when resizing? Is it measured where the body meets the shoulder, neck meets the shoulder, the datum, or any of the above? I made a gauge comparator gauge to help measure the shoulder bump, and made the measurement point on the datum (.40") on .308win. Just making sure it's the correct point before I start using it to measure...

Hoodlum

The datum point. It is not universal; just any point on the shoulder itself. It will be the same point measured before and after sizing

 

[rw496]

Ahh..good question. I was just using the Hornady gauges and noticed that each one is good for several different calibers. So.as long as it's the same point the measurement should be accurate

 

[Hoodlum]

Perfect.... Thanks....
Hoodlum

 

[SWThomas]

I use whatever point touches the inside of my Sinclair bump gauge.

 

[damoncali]

Some calibers have a datum defined in the spec. If you want to match up your measurements with the spec, you'll obviously need to use the same diameter insert. If you just need to make comparative measurements ("how much did I bump the shoulder"), then it doesn't really matter so long as you hit somewhere approximately midway up the shoulder.

 

[Kirkd]

Plus it is only good for that inset as well. You wouldn't want to measure from 1 insert and compare to another insert.


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[AIdog]

+1 for the Larry Willis digital headspace gauge... It measures all cartridges and even measures bullet seating jump/jam... It's become one of my favorite pieces of reloading equipment. This gauge can also be used to examine bullet bearing surface (ogive to base)

 

[AIdog]

Easy to use... Zero a fired case being your chamber casting then set your die height until it bumps shoulder -.0015"

 

[Ultraman550]

Ok here's a question. What about LC brass that is all sorts of fucked up from a machine gun? Do you guys FL size these to where the die body is touching the shell holder the first time and then second or third time around you only bump the shoulder back .0015 or .0020? I use a Wilson case gage to make sure these are in SAAMI specs the first go around but I have not loaded any of the cases for a second time (technically it would be its third though)