Shoulder Setback & Die Bottoming Out

[Phil3]

I am new to reloading, shoot an AR15 in 223 Remington, and have a question regarding shoulder setback and the Redding full length sizing die bottoming out on my Forster C-Ax press shellholder jaws.

Using some Sinclair tools, the average length of fired cases is 1.277". The actual measurement is not relevant...it is odd because of the attachments on the measuring calipers. I carefully adjusted the die downwards a bit at a time, measuring the case until it measured 1.274", so as to give about .003" clearance between the shoulder and the chamber.

I found that to achieve the 1.274" dimension the die was bottomed out on the press shell holder jaws. It would not be possible to push the shoulder back any more since you can not screw the die down any further. This seems very odd to me. What if the rifle had fired shells that were 1.273"? Trying to set the shoulder back to 1.270" (.003" clearance), would be impossible.

All this seems to indicate a very tight chamber, and perhaps it is. It is a Krieger barrel chambered in 223 Remington, not 5.56.

Please educate me on what I may be missing here.

- Phil

 

[RonAKA]

Can't seem to match up your numbers to the standard .223 Remington case dimensions. Where is it that you are measuring 1.277"?

 

[BoydAllen]

The caliper attachments are not designed to measure absolute headspace, which is really a distance between where a circle of specified diameter would come to rest on the shoulder angle of a chamber and the bolt face. They measure how far the shoulder of a case is set back in the sizing process. The headspace, which is a chamber dimension, is not referenced in the cartridge illustration provided by the second poster. I copied the following description from a post on another board. The cited headspace is from the bolt face.

The Mil SPec on AR15 M4 head space is:
3.4.1 Head Space The head space shall not be less than
1.4646 inches nor more than 1.4706 inches when measured to the
.330 inch datum diameter on the first sholder of the chamber.

 

[rocketron]

is the die hitting the shell holder with or with out a case?

if it's hitting w/out a case check for gap when sizing a case.....i think you'll find some

Ron

 

[zedsdead]

I've had to have a few thousandths machined off the bottom of a die before when I was having the same problem you are describing.

Jason

 

[bozo699]

I've had to have a few thousandths machined off the bottom of a die before when I was having the same problem you are describing.

Jason

I have as well had to do this a few times,however I now mill a few thou off the shell holder works great.
Wayne.

 

[kkeene]

If the re-loaded rounds chamber OK you are good to go. A full length resizing die is intended to bottom out on the shell holder.

FYI - Cases out of my friends Kreiger AR barrel get resized .002 inches with the die bottoming out.

Keith

 

[necchi]

I don't have that press, but when setting up, there is a few thou differance between just touching contact and FULL firm contact, and there can be some more with the amount of pressure a person applies to the lever, is a firm hand being used on a full downstroke?

 

[Bob3700]

Redding makes a set of shellholders that are of varing heights. That way, if you have your situation, you can install a shellholder that is slightly shorter.

Give them a try.

Bob

 

[BoydAllen]

All of the Redding Competition Shell Holders are standard height or taller.

 

[bozo699]

All of the Redding Competition Shell Holders are standard height or taller.

BoydAllen,
I bought a set of these thinking they would be the cats meow,wrong why they would make them taller instead of shorter makes no sense to me as it is easy to raise your die but when its bottomed out its bottomed out and a shorter holder is required! I would much rather mill off a few thou. off a low $ shell holder than a high $ redding die! just my $.02
Wayne.

 

[BoydAllen]

The taller shell holders (in .002 increments) allow you to bottom your die on the shell holder at a variety of die settings that may be dictated by the headspace of different rifles, and or differences in work hardening of different lots of brass. By bottoming the die on the shell holder, the slack and spring is taken out of the ram linkage, which may result in more uniform shoulder bump. This is more of an issue when the amount of bump is kept at a small value, which can put one into a situation where one case is tight and another not, with the same die setting. With non-uniform case hardness the degree that the softer cases are bumped, to get the minimum bump on the harder ones can be excessive. Annealing (properly done) helps this situation greatly, as does bumping the shell holder, using a uniform amount of lube, and a uniform amount of pause at the top of the ram stroke.

 

[LWolken]

Die was reamed too deep or the chamber cut in the rifle is on the short side. I'd have the die cut back rather than altering the shell holder. You can send some fired cases in with the die and they will cut it back for your brass. At least thats what redding did for me. Changing the shell holder can cause sizing problems with all the other dies which use that holder, plus it could weaken and rip apart on extraction. Make sure you have an accurate way to measure headspace or shoulder setback. It doesn't take much to get into trouble.

Lance

 

[bozo699]

Changing the shell holder can cause sizing problems with all the other dies which use that holder, plus it could weaken and rip apart on extraction.
Lance

I keep my modified shell holders in die box I have it altered for.Lubed properly I haven't had any problems ??? buy I can see it could and that could ruin your day!
Wayne.

 

[Kenny474]

The OP has .003 chamber clearance after sizing, why does he want to increase that by milling the dies or sanding the shellholder? Full length dies size within SAAMI spec when the die bottoms on the shellholder. And his chamber, while tight, is obviously within this range.

My question is why change anything if the cases are being sized, fit in the chamber, and the gun cycles?

And to answer your original question Phil, If the cases came out of the gun measuring 1.273 (as measured by your calipers and attachment) they would have been crushed to fit in the gun in the first place, as the chamber would be far too tight and out of SAAMI spec. You will likely never see a chamber that tight, so there is no need to size that far.( to 1.270)
There is no need to size beyond what you are already doing, and doing so will create excessive headspace. You likely have a tight match chamber which is at the minimum end of SAAMI spec, which is why you only size such a small amount with you FL die. If the cahmber was any tighter you would likely have issues.

Remember, all generic (not ground to your specs) FL dies will size to minimum SAAMI spec, so that brass sized in them will reliably chamber in all factory guns. There are a few exceptions as have been noted, but your die and method are fine and need not be modified.

Make sure it makes firm contact with the shellholder when you are sizing and you will be fine. You WANT full contact for consistency!

 

[BoydAllen]

SAAMI chamber min, is larger than SAAMI cartridge max. Not that I am making a suggestion, but Lee FL dies are made to cartridge max. I believe that RCBS, to min. Don't know about the others. I would agree that "what iffing" a nonexistent problem may be a waste of time.
Go shooting!