Newly formed brass fits gage...reloaded rounds do not

[cigsour]

Hi All,

I would be grateful for your guidance. As the title states, newly formed brass made on a Dillon 650 and 1500 trimmer will case gauge fine in the Sheridan.

However, when I case gauge my loaded rounds, they won’t sit flush. In station one I have a Lyman M die, station two is primer and powder drop, three is powder check, four is Redding competition seater die and five is Lee factory crimp die.

As an experiment, I slightly undersized a case… Meaning The brass sat below flush in the gage. I loaded that piece of brass and the finished round fit the case gauge perfectly.


Is it OK to slightly undersize the brass? Am I missing something here? Thanks for any and all help.

[smustian]

IIRC the Sheridan gauge has a max/min step. If it is flush out of the forming process then it is at the max dimension. By "undersizing" the case you are bumping the shoulder back a little allowing the brass to fit. Hopefully your gauge is the slotted version so you can see where the original problem is. "Undersizing" by a couple of thousands below flush will work fine and will put the shoulder in an acceptable range.

[cigsour]

Excellent info… Thank you Smustian.

[dellet]

Sounds like you're asking for trouble.

As an experiment, I slightly undersized a case… Meaning The brass sat below flush in the gage. I loaded that piece of brass and the finished round fit the case gauge perfectly.

If the loaded round sits higher in the gauge than an unloaded piece of brass, your not sitting on the shoulder, your sitting on the bullet.

A loaded round should sit exactly like an unloaded case.

Without knowing what bullet you have and the length your loading to. it's impossible to say if your jamming the bullet into the lands or not, but it sounds like you might be. Or you're seating the bullet off center and it's hanging up.

Measure how much of the case is sticking up out of the gauge and seat the bullet that much deeper plus at least .010". If the loaded round now sits in the gauge like it did originally, you just saved yourself a potential disaster.

[Boolit_Head]

You don't say what headstamp the brass is. There is good and bad brass for conversion.

[cigsour]

Thanks for your feedback dellet.

I’m definitely not sitting on the bullet as I have a slotted Sheridan gage And I can see that it is hanging up on the shoulder. It’s the Lyman M die... how are you guys expanding the case mouth? Thx

[cigsour]

Lake city brass...thx!

[dellet]

Thanks for your feedback dellet.

I’m definitely not sitting on the bullet as I have a slotted Sheridan gage And I can see that it is hanging up on the shoulder. It’s the Lyman M die... how are you guys expanding the case mouth? Thx

It's almost impossible to deform a shoulder seating a bullet, unless you are compressing a load.

Try it in the gauge after expanding the neck. My guess would be your going too deep and crushing the shoulder.

[Boolit_Head]

I use NOE's version of the M die and all you have to do is let the second step enter the case mouth just a bit. Unless you are seating cast bullets you really don't need the M die.

[cdl]

A "Death" crimp can crush a shoulder too.