Minimum safe loads- which data do I use

What is the shoulder length from base on full sized or new factory brass and brass fired in the gun . If the difference is enough to cause problems the fix would be to fire form brass to your chamber with powder puff loads .

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The case head stumps me. I would have thought a headspacing problem but in this case, no pun intended I have no clue. All I can add, if you want to try is how I set up my die which males the brass a custom fit to your chamber.

This is how I set up my sizing die for bottleneck cartridges.

1. Take a once fired factory round and blacken the neck and shoulders with a Magic Marker or Sharpee pen. Some people like to smoke the neck and shoulder, but I find the Magic Marker/Sharpee pen a bit better.

2. Carefully lubricate the case.

3. Loosen the lock ring on the sizing die and back off about two turns from when the die is set to touch the shell holder.

4. Size the case. Note where the marks are on the case and turn the die down about a half a turn and size again. Turn down some more, and resize again. What you are looking for is the marks on the blackening just touching the shoulder.

5. Clean the lube from the case and try it in the rifle. It may chamber just a bit on the snug side. If so, turn the die down ever so slightly, lube and size again. Wipe off the lube and try in the rifle. If it slides in as easily as a factory round, you should be good to go. If not, usually one more very slight adjustment should fix the problem.

6. Tighten the locking ring for the die and you're done. You have just set your sizing die up for a custom fit to your specific rifle, rather than a generic one size fits all guns.

Paul B.
If these are first time fired factory rounds, I'm stumped! Never seen this separation before on a new factory round first time fired!

However, if they are reloads from factory brass, the shiny ring on the brass above the case head leads me to believe that it's a headspace issue & F/L resizing without setting the die for correct head spacing is the problem.
Correct head spacing is measured from the centre of the case shoulder to the case head, with your F/L sizing die set up to accommodate this dimension.
Tools are available to measure the headspace using a fired case to find the dimension, but the correct setting can be found by trial & error when setting up the F/L sizing die.
Good luck resolving the issue (y)
Headspace like already said, but also just maybe the powder measuring went bad. I've experienced some of that with both electronic and beam scales and it took a while to catch on. How did you measure CL? About the factory loads picture, the one with 3 before the separation and 4 after: it would be nice to know all the dimesions of those cases measured at several points from web to shoulder, and the length from base to shoulder and base of neck. If ones prior to the separation event measure less, then something strange is happening. Did you alter your cleaning process recently - products, patches, brushes, etc.? We are all wondering with you.
Thanks all for the replies. I cannot account for the apparent "increase in headspace" as it appears in the rings around the case. OTHER THAN the possibility that I have over resized the brass. I have been shooting reloads from this rifle for 20+ years and some of the brass is that old. Those two factors in combination might produce the case head seperation. I have not been able to put the calipers to these cases but I am interested make the following comparisons: Measurements of the new factory un-fired vs once fired vs the cases that have separated. I'm also going to try and gently polish/ clean the chamber in an effort to make sure that the "rings" I'm seeing are not the result of carbon etc left from the separated cases.
Also- I have enough unfired new brass to duplicate or come close to the loads in question, with new brass. Come spring I have a friend who has offered to go through my reloading process w/ me and "critique" my process. He shoots @ 600 and 1000 yards competitively, and does a lot more reloading than I do. For the present I will stick with new brass. I dont shoot that much.
In any event, for now, I am likely out of shooting and reloading 'til April. Too D@mn cold. Depressed.... Thansk again for the replies. IF I get a chance to do any more work I willl update the thread. CL
I don't trust the paperclip method at all. I have used the little battery powered led lights that are a single light on a flexible stalk, put on my readers, and move light, eye, and case around. The light will make a distinct shadow ring if an internal separation has begun. I've used my borescope too, but prefer the little led. I've verified the suspicious ones by wasting a few cases by grinding half the case off. Works for me. EE2
Thanks EE2-Your LED Light sounds like a good plan. I pulled bullets from the last box that had seperated cases. Eventually I will do a little grinding/cutting CSI and see what I can find. HATE to scrap what looks like decent brass but its not worth the risk. I re-scaled several charges and verified accuracy with another scale. I was spot on within a couple tenths of a grain from one scale to the other. Hated to do that to but I destroyed the powder in those rounds. Putting it back in the canister after a few months seems like a bad practice too. Thinking about getting one of these too. Might be a Santa gift to myself.