Headspace Question

[Elkbane]

I just made some 260 brass by expanding some once fired Lapua 243 Win brass. I used an expander mandrel to expand the necks, then ran them through my Forster FL dies. I then turned all the necks down to 13 thousands. The brass looks great and is very uniform.

Question I have is on headspace. The headspace on the converted 243 cases measures 1.625" and my usual fired round headspace on the 260 comes out at 1.6275 before sizing,all measurements with Hornady tool - I'm using the term headspace here but I mean case length to the .4" datum line on the case shoulder). I was planning on fireforming the "new" brass with bullets lightly seated in the lands to keep firm contact between the case base and the bolt face. Is 2.5 thousands too much headspace to be safe, or should this work out OK? I need to know before I convert too many cases.

Thanks in advance for your help/comments.
Elkbane

 

[rstreich]

2.5 thousandths shouldn't be too much, but what is the measurement before you FL size it?

BTW, seating a bullet long won't keep the case head against the bolt face.

 

[rayjay]

You will be fine. I normally bump my ppc or br cases a thou or two.

 

[jo191145]

gunamonth
The firing pin spring easily has enough energy to reseat the bullet until the shoulders bottom out in the chamber.

Elkbane
As others have said your within parameters. Nothing dangerous about that much expansion on the first firing. Factory ammo headspace tolerances are usually much looser than yours.
But.....
Can you not back out the FL die to increase your headspace?
If not and if this is your Savage you could reset the headspace on the gun itself.

Seeing as I do not use factory ammo I always set my Savage barrels for a slight crush fit on NEW brass then adjust my dies to bump .001 or so. I only shoot one set of brass at a time.

Theres a few theories on why crush fit fireforming is preferable and I'm not talented enough to argue the merits but it sure seems to have improved the accuracy of my guns while fireforming.
And I save money on all those Go- No Go gauges.

 

[Elkbane]

Thanks for the replies guys, that's what I wanted to know.

rstreich:
My 260 chamber headspace is set to 1.628 with guages. It's slight contact to the go guage at the tail end of the bolt throw. Fired cases measure 1.6275. After FL sizing in the 260 dies, my brass measures 1.6265.

The issue was the that the 243 cases, once-fired in another rifle, measure 1.625 even after FL sizing in the 260 dies - the case shoulder never contacts the shoulder of the dies, so they come out shorter. And I'm not getting enough contact on the 243 case sidewalls to "squeeze" the case and make the shoulder move froward. These cases measure 1.625 before and after FL sizing.

All, don't know whether this makes sense, but the reason I load with a jam for fireforming is that I just think it makes sense to start the ignition with firm contact on the case base. I realize that the spring will drive the case forward, but I'd rather have it start tight than sloppy loose - just seems to make more sense.
Thanks again,
Elkbane