Measuring shoulder bump with coal vs shoulder comparator

[Nevrsummr]

I removed the extractor plunger and firing pin from my bolt. I then bumped my shoulder using a Redding Type S bushing die and the Redding Competition shell holders. Starting with the .010" shell holder I sized the brass and checked the fit in the chamber. I worked my way down until the bolt would close with out tension (.006" shell holder for my particular chamber). I then measured the case using my headspace comparator to get the correct base to shoulder number to go off of. What I have observed is that if you do not anneal every time, you will get a different shoulder bump using the exact same press/die/shell holder set-up. This is due to a difference in brass spring back as the brass work hardens. I anneal immediately before bumping my shoulder and have found that this give the most consistent shoulder bump.

Interesting on the annealing. I read a recent thread in which a member was saying anneal last for consistent neck tension so i was trying to get these all sized so that i could go anneal.

 

[Taylorbok]

So, i followed the steps in the video and the instructions on the redding shell holder kit. Started with the .010 shell holder and with the die firmly touching the shell holder. My bolt closes the same tension with or without the sized case in it. Shoulder comparator reading before sized is 2.212 and after sized is 2.213 so the shoulder grew .001. Should i just call it good with the .010 shell holder? Or should i try the .008? I dont think i will be able to feel the difference. My ejector is removed from the bolt btw.

do you have firing pin out also? Yes try the shorter shell holder, most people move the shoulder back .002"
Everyone I know of anneals before sizing.

 

[VenatusDominus]

So, i followed the steps in the video and the instructions on the redding shell holder kit. Started with the .010 shell holder and with the die firmly touching the shell holder. My bolt closes the same tension with or without the sized case in it. Shoulder comparator reading before sized is 2.212 and after sized is 2.213 so the shoulder grew .001. Should i just call it good with the .010 shell holder? Or should i try the .008? I dont think i will be able to feel the difference. My ejector is removed from the bolt btw.

The shoulder can grow like yours did because the die will squeeze the body and the brass will flow toward the shoulder until it meets the resistance of the die, and then flow up the neck. If there is the same bolt resistance with and without the case, then it sounds like you are good. Is this once fired brass? As others on this site have noted, it may take up to 3 or 4 firings of virgin brass to grow it to fully fit the chamber. Hotter loads will obviously grow your brass quicker. Firing pin must be removed or the spring tension will be what you feel, not the brass in the chamber.

 

[Petey308]

The case will initially grown in headspace before it shrinks, because the material goes in the path of least resistance. If you keep screwing your die down, it will eventually start bumping the shoulder down.

If needed, use a shorter shell holder to allow more of the case to enter the die.

 

[Petey308]

Follow these insctructuons. It's how I do it as well.

 

[Nevrsummr]

Pulled firing pin. That made a huge difference in feel. Having some interesting results. Going to follow all yall's advice n anneal first.

 

[VenatusDominus]

Pulled firing pin. That made a huge difference in feel. Having some interesting results. Going to follow all yall's advice n anneal first.

Also the extractor plunger and spring (not the extractor claw) needs to be pulled

 

[Nevrsummr]

Went through exact same process on a different rifle. 6.5 max. Made it all the way down to the .002 shell holder and not enough bump. Had to go to a standard rcbs #4 to get enough. So very different results from the first rifle