Can someone explain .308 headspace to me please?!

[Utectok]

Possibly depends on how much tolerance between neck dimensions on case and in chamber to start with?
I‘ve not experienced failure to load since I started running cases through the action prior to loading, but it wouldn’t be a big deal if it happen.
Ken.

The base of the case expands and you resize it with a body die? Ken.

Yes Rcb body die is what I use. Doesn’t affect neck size and should bump is controlled by a rcb set of special shell holders. So you pick the correct thickness of shell holder and push the ram all the way home on the full length body die (odv with some lubricant on the case).

 

[drone]

I can't handle all this bs about headspace. My method of finding if my headspace is acceptable is a procedure I picked up many moons ago, I can't remember where, it goes along the lines of fully resize your case then pop it completely deprimed into the chamber to ensure the bolt closes on it. Remove it then insert a SPENT primer in the pocket but do not push it completely home. Insert the case into the chamber and gently close the action. gently remove the case from the chamber and measure the case from case mouth to neck then over the primer to the neck.
The image shows a case from my 308 Browning BLR where the primer is protruding just under 0.008" and the other is a 22 savage hi power from my 1918 savage model 1899 protruding 0.002"
I measured them with a digital caliper which is OK for comparison readings but not really highly accurate enough for accurate measurement.
My readings say my 107 year old savage is still just about at the minimum headspace and the 1981 BLR is starting to get near the maximum.
Best thing about it is it's really inexpensive and, if one is careful, accurate and bs free.
FWIW the 22 hi power was resized in a redding FL sizing die and the 308 in an RCBS small base FL sizing die.
Provided your chamber and brass are clean this method gives an almost irrefutable figure though some will probably argue that.I popped this image of a case from my 94 win 30/30 that shows headspace of 0.0015" which is really at the minimum.

 

[jthyttin]

I can't handle all this bs about headspace.

Your method has two problems.

First measuring "to the neck" is no exact science (especially in conjuction with next point).

Secondly resizing does not give you any reference that has something to do with headspace.

BTW 308 is on of those chambering where CIP maximum round won't fit in CIP minimum chamber.

 

[Bowland blades]

Good evening. I am trying to get my head around the concept of headspace and in particular how and why case shoulders get bumped.

For context I've been shooting and reloading about 6 years (centrefire) and have all the basics down. I shoot a Tikka .308 which is used exclusively for stalking so I don't need 'match grade' ammo or precision.

A few years ago I had a new experience whereby some home loads I'd put together misfired. Closer inspection (ruling out firing pin issues etc) revealed that some of the brass (nny) had had the shoulders inadvertently bumped back excessively. Looking into this is turned out to be a newly acquired die set that had a different (and unadvertised) die included while i inadvertently misused. Anyway, I chucked the main offenders, pulled the rest, shelved the brass and bought some new Lapua.

Looking at it today with a comparator set to hand, the fireformed Lapua (neck sized) comes in at an average of 1.621" on the Hornady gauge. The shelved brass upon measuring has a comparative average figure of 1.615". My questions are, if you can help/advise:

Is 0.006" enough to produce misfires (soft pin strike)?

Is the original brass salvageable/safe to reuse?

If shooting a bolt-action stalking rifle, fireforming the brass from new and neck sizing thereafter, do I need to concern myself with headspace? (With bullet, primer, powder, coal etc being kept the same)

And if so, how is it best done/checked and what does it achieve? (I'd based my initial assumptions on fire-formed, neck sized and trimmed brass being 'perfect' for my particular chamber, therfore not requiring extra attention).

If it helps, codes on the Lee dies are: (fl) LEE - 308 - 13 and (neck) LEE - 308 WIN - G9.

I hope that makes sense and that you might be able to explain the above to me. Thank you.

Lets make this simple . Clean a once shot case , check if its within length spec ( trim if its not but thats rare ) you do this by measuring with callipers . Take the spring out the bolt and feel for tension 99 out of 100 it will be fine , though each use the brass will flow a bit more - you will feel tension now closing the bolt and the case needs the shoulder pushing back
Get a book on the subject and read it

 

[Utectok]

I mean basically if your worried about headspace you need … go no go gauges
Otherwise resize to sammi spec and you’ll be fine not really worth overthinking this in my view