Sizing/headspacing

[F. Guffey]

“This aside, if the die's headspace (shoulder to a touching shell holder) is at its long end of specs, the gap between shell holder and die bottom may well be extremely tiny and....”

We all (should know) if there was such a thing as a die having head space the distance would be measured from the shoulder/datum to the deck of the shell holder, not from the shoulder to the top of the shell holder, if the die had head space the distance would be reduced .125” because of the deck height of the shell holder.

As UncleNick knows I do not use a back light, I simply use a feeler gage. Back to the gap, it is possible to remove the shell holder before the ram is lowered, simply rotate the shell holder until it will slide off the ram and case at the same time, then remove the die with the sized case, after removing the die with the case protruding reinstall the shell holder, WHY? Measure the gap. Most will have problems installing the shell holder on the gage, not a problem, remember, the deck height of the shell holder is .125” without a shell holder the protrusion can be measured with a depth gage, or, remembering the deck height of the shell holder is .125”, use a magnum/belted shell holder.

Again, for those that own and coveted head space gages, remove the die, remove the primer punch/neck sizer plug assembler then drop the coveted head space gage into the die then install the shell holder, same thing, measure the gap between the die and shell holder, the gap will indicate the difference between the length of a go-gage chamber and a minimum length/full length sized case.

Again, SAAMI does not designate head space on the cartridge, SAAMI designates head space if the chamber. Again, head space is measured from the shoulder/datum back to the bolt face, very few refer to head space as fill in the blank as in head space is ________________________? I fill in the blank with the distance from the datum/shoulder to the bolt face.

I do not covet head space gages, in the time it takes to order one I can make one to fit my chamber with .000” clearance. I can also make one that fits any chamber from go to infinity.

I have 10++ 8mm57 mausers, I use one set of dies when sizing cases to fit each one of them, I do not grind the die, I do not grind the shell holder, I do not use Redding competition shell holders, one day every thing I own will belong to someone else, can you imagine, RCBS replacing all those bubb-upt dies?

I have dies that belong to someone else, some were very respected shooter/reloaders, to avoid going beyond minimum length/full length size I am required to shim the die off the shell holder, it is nice to know how to determine how much was removed from the die.

F. Guffey

[F. Guffey]

“gap between shell holder and die bottom may well be extremely tiny and....”

When a case whips my press I want to know by how much, “extremely tiny” is not a value.

I must not be a vain individual, I think nothing of reaching for the humblest of tools, the companion tool to the press, the feeler gage, a $5.00 +/- a little from Harbor freight to measure a gap, to make adjustments, I give the tool the class it deserves, after all what other tool qualifies as a standard, transfer and verifier.

F. Guffey

[Unclenick]

Bart,

I don't disagree at all on controlling shoulder setback. But since the OP seems to be working with once-fired cases from someone else's chamber that are reluctant to fit in his chamber, getting maximum sizing on the first pass seemed to be to be justified. He won't be able to measure setback until he's fired them once in his chamber. Still, you are correct that this is not the practice he will always want to follow. It's just for the first pass, and I should have pointed that out.

[F. Guffey]

Unclenick, it is possible to measure the length of the case from the shoulder to the head of the case before it is fired, no matter what chamber the case was fired in. I have gone to the range and purchases 200 cases +10%, before sizing the cases I have measured them for length from the shoulder/datum to the head of the case, matching cases to the chamber they were fired in is possible, again, my favorite case is a case that has been fired in a trashy old chamber.

measuring before sizing makes it possible to determine the effect sizing had on the case, again, I know when the case is sized by the gap created between the die and top of the shell holder. The advantage to cases fired in ugly/trashy old chambers allows the reloader to size cases that fit.

Then there are bench resters, again, bench resters do not have chambers like chambers that come in a reloaders rifle, if bench resters had chambers like most of the chambers in my rifles they would require therapy, especial with their insistence on full length sizing.

F. Guffey

[F. Guffey]

The question is always asked “What to do with new, unfired, 50 or 100 cases in a bag” The answer is always the same ‘full length size’, I don't, the new unfired cases are minimum length/full length sized, I would only be happier if cases were available for reloaders that know what to do with a case that is oversized, at one time I could acquire cylinder brass, a 35 Whelen case with with straight walls and 2.650” long, outside of cylinder brass there is the 280 Remington case for 30/06 chambers and forming dies to form cases for chambers that are shorter than the 30/06 case etc..

Back to mindlessly sizing a case to minimum length/full length size. Again, full length sizing is not necessary if the reloader knows the dimension of the chamber the cases are being sized for.

F. Guffey

[Unclenick]

Normally I would agree. Go straight to headspace measurement and correct for that. But if you look back at the OP, these cases are 0.003" too fat at the shoulder, and this seems to be after using the sizing die. Very odd. That's why the suggestion that he has a neck-size only die rather than a full length sizing die makes sense. But if that's not the case, the only thing I can think of to try is to run the sizing die down hard and check the diameter again. At that point, if it still doesn't fit, I'd have my small hole gages up in the sizing die, figuring it might be a bad die and probably trying another.

[Bart B.]

I've always thought full length sizing was the process of reducing fired case diameters and its headspace any amount. It does not mean sizing the case back to its original dimensions when new nor back to SAAMI minimum dimensions which are typically less than what new cases are.

Unclenick, thanks for the clarification; it makes good sense to me, now.

[mehavey]

UncleNick, I'm a boundary-value kinda guy in these instances. I'd run the sizing die down to contact +1/16 turn to remove all spring in the press; Size the case (well-lubed); and chamber it.

If it fits--case solved. Now we can apply finesse in the follow-on.
If it doesn't fit (and commercial ammo still does), bad die or a small-base problem.

[F. Guffey]

“I've always thought full length sizing was the process of reducing fired case diameters and its headspace any amount. It does not mean sizing the case back to its original dimensions when new nor back to SAAMI minimum dimensions which are typically less than what new cases are”



Then that part about “it makes good sense to me, now” The case does not have head space, the case has a length that off sets the length of the chamber, the length of the case is measured from the shoulder/datum to the head if the case. Full length sizing is full length sizing, the confusion is about full length sizing to ________________ (fill in the blank), there is full length sizing to minimum length/full length sized, Then there is the problem of assuming as in assuming the case is restored to minimum length/full length size. That brings us back to determining if the die made it to the shell holder when the ram is raised when full length sizing.

If the case is holding the die off the shell holder there will be a gap between the die and shell holder, if there is a gap between the die and shell holder there is no full length sizing back to minimum length, again, it is possible to measure the gap, a less effective method involves light passing between the die and shell holder when the ram is at the end of it’s stroke. The additional fractional turn of the die after contacting the shell holder increases the presses ability to overcome the cases resistance to sizing.

Isolating the problem: Attempt chambering the sized case before seating bullets. If the case chambers before seating bullets the problem could be caused by the seating die adjusted to crimp ‘too much’. Another set of dies? Another set of dies, for me, is a matter if choosing dies from a different drawer. Then there is the diameter thing, the case has a taper, the case is round, the round case with a taper creates varying diameters, measuring the diameter of a case anywhere along the length of the case body is doable, determining if the diameter is different at any point along the case body when compared with another case is simple, convincing someone it can be done could take a like time.

Chamber gages, I make chamber gages, for chamber gages I do not have, I have take off barrels. if the take off barrel has a bore that, for any reason, is worn out, rusted etc., it becomes a chamber gage, simply cut the chamber off then clean up in a lathe. Then it become a matter of sizing a case then dropping the case in the gage and measuring case head protrusion, point? By the time the case is sized, primed, powdered with the bullet added the reloader should know if the the reloaded round is going to chamber.

F. Guffey

[F. Guffey]

I'd run the sizing die down to contact +1/16 turn to remove all spring in the press; Size the case (well-lubed); and chamber it.

If it fits--case solved. Now we can apply finesse in the follow-on.
If it doesn't fit (and commercial ammo still does), bad die or a small-base problem.
mehavey is offline Report Post


Mehavey, removing the spring (caused by the cases ability to resist sizing) does not guarantee the cases is sized when the ram is raised, the reloader assumes the case is sized when the ram is raised, to determine if the case is sized when the ram is raised check the gap between die die and shell holder, anything (the case) holding the die of the shell holder indicates the case did not get sized, meaning, it is possible the die could require and additional 1/4 turn to 1/2 or an additional 1/2 turn added to your starting 1/4 turn.

At some point a reloader with ambition to improve in method and technique will move away from wild guessing, “If it fits”? I do not settle for anything less than ‘By how much’.

“If it doesn't fit” Back to the assuming reloader assuming the case was sized when the ram was raised, and the deductive reasoning, if the relaoder had a commercial case that would chamber he would have a case he could use in a comparator, chambering the full length sized? case would not be necessary.

Then there is the other method and or technique, a reloader should be able to determine the length of the chamber from the datum/shoulder to the bolt face, there should be no mystery or guessing when deterring if a case will chamber after sizing.

And again, it is possible to determine if the die and shell holder has the ability to restore a case back to minimum length/full length size, but to accomplish this task the reloader needs a good understanding of transfers, standards and verifying.

F. Guffey

[Bart B.]

SAAMI does designate head space on the cartridge. In the reloading industry, it's typically called "case headspace" so it won't be confused with the barrel's chamber has. For the .308 Win., case headspace is the 1.634"-.007" dimension from case head to the reference point on the shoulder shown on the cartridge case diagram in the following SAAMI document:

http://www.saami.org/PubResources/CC...Winchester.pdf

What's typically called "headspace" (in reference to the chamber) and sometimes called "chamber headspace" is the 1.630" to 1.640" dimension from the bolt face to the reference point on its shoulder shown in the barrel chamber diagram in the above document.

Note both reference the .400" diameter datum/reference point on both the chamber shoulder and case shoulder.

[F. Guffey]

Again, another SAAMI drawing without a head space designation to the case, again, a foot note designating head space as it applies to the chamber.

Then there are the bench rester shooters that full length size with total disregard of chamber length, not me, I off set the length of the chamber with the length of the case from the shoulder/datum the head head of the case.

F. Guffey

[F. Guffey]

Then there are the gages that are comparators and case length gages labeled as head space gages, some choose to have 2 standards, I don’t, I have one standard for head space? I refer to head space as the chamber length from the datum/shoulder to the face bolt, when dealing with head space I fill in blank, meaning head space becomes a dimension, not a term.

F. Guffey

[hooligan1]

Guffey, would you be so kind as to write a book or produce a quality video illustrating every proces you go through from "brass from an ole trashy chamber" to a finished cartridge?
I will buy a copy no foolin.

[omnimedic]

Sorry for the delayed response... Had to go out or town unexpectedly. Thanks for all the replies. Here's where I am:

I'm a very analytical person, and do lots of troubleshooting on different things; to that end, when I'm working on something, I normally don't change more than one variable at a time so if I fix it, I know which variable fixed it. I broke my rule this time and made several changes:

1) I am using a FL die, and adjusted the sizing die with very close attention to detail, and according to the instructions you guys gave: ram all the way up, screw the die down till it touches the shell holder, add 1/16 turn, lock it down

2) I slowed down the speed I was running the arm; I may have been going too fast and not giving the brass time to erase its memory and get over the springback.

3) I had overlooked case lube, as someone mentioned. Lube is good (insert your own joke here)

So... With all those steps, my cases are within spec when measured with calipers. I haven't loaded any yet, but we'll see what happens...

Thanks for all the help!
-Omni