22 Creedmoor shoulder case bump

[US MILITIA AOD]

Good morning and Happy New Year,

I am putting together a 22 Creedmoor AR10, the barrel is KAK Industries 18" 1X7 twist. I purchased 6mm CM Hornady brass and sized them down to a 22 CM dimensions using a Lee die, I also used a Hornady Headspace Comparator and the bump on the shoulder measured 1.530, after about 5 cases I used a L.E. Wilson Case Length Headspace Gauge and noticed that it was sticking out about 1/32" to 1/16" so I lowered the die ever so slightly and re-sized it and again tested it with the Wilson case gauge and it was perfect this took the shoulder bump to 1.525, I just finished cleaning the brass my next step is to anneal then trim.

So this is my question, I am hoping that a member here has a Hornady factory unfired 22 CM cartridge and measure the shoulder bump and post it here.

Thank you ever so much.

 

[RegionRat]

This may end up being one of those situations where we go down a rabbit hole because those Hornady tools tend to have rough tolerances and that makes sharing non-referenced dimensions risky.

If I just do as you ask, running the 0.400 tool, then I would get 1.532" - 1.533" on virgin factory brass. Just goes to show why we can't share numbers without a reference to an actual GoGage.

For example. My Alpha brass is 22 CM from the factory.

When I compare Alpha 22CM brass to these SAAMI specs, it is all at zero or -0.001 referenced from the GoGage.
My bolt guns run +0.001" compared to the GoGage and will close hard on the gage with a piece of tape on the gage but close easy on the gage.
When I just zero on the Hornady tools as you asked, they do not match the GoGage which is supposed to be the chamber MIN of 1.541" and none of that sounds like your numbers or even close. That is why I zero on a GoGage and reference to the 1.541" spec.

I always suggest owning the GoGage but even without one you can still make progress by using your chamber and a tape method.

Lets assume your virgin 6mm brass is made to GoGage or under. If you carefully neck a sample without bumping the shoulder, the chamber should close on it. (If it doesn't we have to punt cause then something else is going on.)

Then, if you strip the ejector from the bolt, and use a layer of Scotch tape on the base of the case, you should be able to roughly estimate the headspace datum of your chamber. Using just the upper, apply only finger pressure to close the bolt on your taped case till you would need more force to close. Zero your Hornady tools on your virgin brass and measure that taped case for an idea of your headspace.

Keep that case with the tape on it to transfer a reference with your Hornady tools till you wrangle yourself a legitimate gage, or just keep rolling once you get cases to chamber with a little margin and call it good. YMMV

Merry Christmas and Happy New Year!

 

[US MILITIA AOD]

Thank you for your response it is appreciated. If someone else has an original 22 Creed shell casing unfired and unmolested and can get me the measurement it would be greatly appreciated.