Prepping fireformed brass

[SKWERLZ]

Also, are you certain you have fully fireformed the cases with just one firing? Sometimes multiple firings are required to fully form the cases to the chamber, and with just one firing you may, or may not have reached the full chamber form just yet. I would measure the chamber to be certain before attempting to bump the shoulder back any.

^^^^^^

 

[SKWERLZ]

Sooner or later, you are going to have to start full length sizing your cases, probably after the third firing.

So the best thing to do is full length size from the very start and tune accordingly.

I’ve played that game before, it’s better to stay on full length sizing because eventually cases get tight and are difficult to impossible to get back to size when neck sizing or shoulder bumping for extended intervals.
Plus load changes instead of the load stability you get with consistent FL sizing

 

[mikecr]

Seeing as I do not wish to FL size my fireformed brass, does this mean I'm better off getting a die dedicated to shoulder bump?

If all you want is shoulder bumping then yes, it's best accomplished with a custom bump die.
That's a die that slightly squeezes the body (but not to yielding/sizing), and just moves the shoulder.

I do this with custom body dies from JLC Precision.
So that the result is as described, I send slightly over pressurized cases. Jim makes a die for me from these cases, and I get a perfect bump only die for normal pressure brass.

I partial neck size with Wilson hand dies.

 

[K22]

Sooner or later, you are going to have to start full length sizing your cases, probably after the third firing.

So the best thing to do is full length size from the very start and tune accordingly.

This is excellent advice Plus:

Especially if you don't want to get caught in the field or in a match or even at the range after a long drive and the ammo won't chamber or worse, chambers with excessive bolt resistance galling the bolt lugs.

And you sure don't want to have to check each loaded round in the rifle chamber to verify that it chambers properly. Besides being a safety issue, it's labor intensive.

 

[CharlieNC]

You can set your die to 1. FL size -shoulder lengthens(wrong) 2. FL size with no shoulder length change, typical for fired brass that chambers easily 3. FL size moving the shoulder toward the base, because the brass doesn't chamber correctly because the shoulder is contacting the chamber surface before the bolt closes. How much you need to bump brass that NEEDS the shoulder moved will be a feel/bolt operation judgement. Or you can use a spent primer to measure the bolt face to case headspace(clearance). My hunting rifles 0.001-0.002, AR's 0.003-0.004 works well when hunting in below freezing temps and avoiding forward assist to battery.

Just to elaborate a bit partially seat a primer, insert into chamber, and close the bolt to finish seating. The resulting length represents zero headspace, which you can use to establish the sized length to achieve the desired headspace. Very accurate and reproducible, and not technique dependent.

 

[Killick]

 

[mikecr]

Absolute declarations only serve to fail tests and discredit the source.
It should be obvious that everyone does not "have to start full length sizing".