Headspace comparator question..

[Unclenick]

Sounds right. To get a tighter measurement that compare apples to apples, set the die out slightly more so there's no cam over and a gap both ways. Find the right feeler gauges for the caseless shell holder and the one for the die with the case in it and subtract the former from the latter. By getting the same feel of friction on the feeler gauges both times, you are going to get a more certain measure of the difference. Cam-over, on presses that do it (Lee's presses have stops to prevent this), has so much leverage you can easily be squeezing with far more deforming force than you realize.

[F. Guffey]

When sizing a case and the ram is all the way up I have a gap of .020 in between the shell holder and the die . I assume that means I have .020-ish of flex in my press ???

The gap created when the ram was raised to the top indicates deflections, then there is the ability of the case to resist sizing. That is where everyone runs off and leaves me, they fire a case, then fire it 4 more times to get the case to maximum size and then claim they start over by full length sizing, I can not do that because after I fire a case 5 times, it has been fired 5 times and that increases the cases ability to resist sizing.

Forum members are covering the forums like the wind trying to reinvent new and different words and phrases to replace old word meanings and phrases. The .020" gap could mean the case whipped your press by .020", the one thing for sure we should know when there is that much gap the case did not get stuffed into the die.

That brings us to the part were we should know our dies, in the effort to cover the forums like the wind members have started labeling everything a 'head space gage so I will try to make this simple, I would use the head space gage that in used in the chamber to determine of the bolt will close on it. I would remove the primer punch/sizer ball assemble then install the head space gage that into the shell holder, raise the ram and then adjust the die down to the gage, after the die contacts the gage I would use a feeler gage to check the gap between the top of the shell holder and bottom of the die. If the die was a 30/06 full length sizer and the gage was a 30.06 go-gage the gap would be .005" in the perfect world.

What could be learned from this test? The reloader should understand when the die contacts the shell holder when sizing the case is full length sized, I have long chambers, to compensate for the long chambers I adjust the die off the shell holder, again, I have one that requires a gap of .014" for a chamber that is .002" longer than a field reject gage.

Wait! Before everyone tries this at home, remember, there is a chance the head space gage will not fit the shell holder, not a problem, the deck height of the shell holder is .125". To solve the problem use a shell holder that is used on larger case heads.

F. Guffey

The die and shell holder barely touch meaning I can barely feel it cam over

Remember, progressive presses have a shell plate, the shell plate is mounted to the ram in the center and the case is installed off center.

[Bart B.]

Does this. . .

The reloader should understand when the die contacts the shell holder when sizing the case is full length sized

. . .mean that a case sized in a full length sizing die such that the shell holder stops a few thousandths short of touching the die bottom is not full length sized?

Even if the resized case body diameters from the pressure ring to the shoulder and the neck diameter from the shoulder to the case mouth are smaller and the shoulder is .001" closer to the head that before it was sized?

[F. Guffey]

closer to the head that before it was sized?

Bart B. I thought you treated Old Roper in a manner rather rude, if not for that I would not take the time to quote you.

When I secure a Mauser barrel to the receiver and the barrel face contacts the 'C' ring, that is it, the barrel is not going to get closer, I can torque it and stretch the threads. What you need to try to understand when the die contacts the shell holder, that is it, the distance from the deck of the shell holder to the shoulder of the die is not going to get closer, there is no way to crush the shell holder or reduce the length of the sizer die from the from the bottom of the die to the shoulder of the die.



F. Guffey

[Metal god]

yeah but your not taking in to acount the flex/give in the press it self . I can set my die to lightly touch the shell holder and I can torque it down on the shell older . Just because they are both touching the shell holder does not mean the case will be sized the same .

I just adusted my die down to where the press would not cam over . I then sized 5 cases . The average size from shoulder the head face was 1.612 . that is .010 shorter then I size my cases and .012 shorter then my fire formed cases . That makes me think the die will size a case at least .013 shorter then my chamber . What does that all mean ?? I don't know never checked all that before

Am I right in saying the SAAMI "B" measurement on the 308 Win case is Max 1.634 and min 1.627 ?? if so thats no where near what I need to size my cases to for a good fit .

[Bart B.]

Guffey, I didn't ask about the die crushing the shellholder. Instead, I asked about the die not touching the shellholder and .001" space between them making the case have smaller dimensions in all surface areas from the pressure ring forward; even more space in some situations.

In simpler terms, does the bottom of the die have to touch the shell holder when the ram's all the way up to have a "full length" sized case and if it's not touching, the case isn't "full length" sized?

Metal God, you asked

Am I right in saying the SAAMI "B" measurement on the 308 Win case is Max 1.634 and min 1.627 ?? if so thats no where near what I need to size my cases to for a good fit .

Yes, that's right.

That makes me think the die will size a case at least .013 shorter then my chamber.

That can happen if you die's a bit short on headspace and/or the shell holder height is less than .125"

But the important thing, in my opinion/experience is that fired cases have their shoulder set back about .002". It doesn't matter what their exact measurement is; it could be anywhere between 1.627" and 1.632" if you chamber is within SAAMI specs of 1.630" to 1.634".

If you fire formed cases are 1.624", I think one of two things are happening. One's that your barrel chamber is way short of normal. The other's that your loads are well under max and the case shoulder may be pushing back quite a bit from firing pin impact. But these are only guesses and without more details/information, that's the best I can come up with.

Will a case with headspace at 1.630" allow the bolt to close easily on it?