Need guidance / partial full length sizing of brass

[10 Spot Terminator]

I have ran across a glitch after neck sizing 60 fire formed cases for my 30-06. All came from 1 lot of factory loaded Rem. ammo. All were neck sized in one setting with new Lee dies. All were trimmed to length well under max specs. The problem is this ,,, about 6 of the rounds you cant close the bolt on and about 10 of them they have a noteable resitance closing the bolt . For the life of me I cant find the dimension fault in these cases. I have checked the shoulder setback using a stoney point comparator with a .375 and .400 collet to allow measuring at 2 points along the shoulder and no difference between those that go and those that dont. I have checked the cases at the datum line on the shoulders and at the widest spot on the case web with no noteable variations. bullet seating is consistant at the ogive and .020 off of the lands. Those cases that close somewhat stiffly show a light scuffing on the very edge of the case rim on the face from rotation of the bolt. I have glanced at threads over the years where some had partial sized cases with a full length die and as I have a spare RSBS die with the decapping pin not installed could someone walk me through this proceedure ??? I will pull down these rounds and try it on the known "no go" cases and reassemble to see if changes them at all. Thanks for any help you can give. 10 Spot

 

[bgdv1]

i ran into the same problem with my 30-338 win mag. i ended up having to set the sizing die down some more to set the shoulder back a little and everthing work then.

 

[steve4102]

1. Put the Shell Holder in the press and raise the ram.

2. Screw the Full Length(FL) Die into the press so it is about a "nickle's thickness" above the Shell Holder.

3. Lube a "Fired" case (walls and inside the neck) and squash it.

4. Remove the Lube and try closing the bolt on it in the chamber.

5. If the bolt closes with no resistance, screw the FL Die into the press about 1/8-1/4 turn and repeat steps 3 & 4.

6. As you feel the resistance begin, slow down how much you screw the FL Die into the press so you are at about 1/16 of a turn, or "Fine Tuning". At some point you will not be able to close the bolt and you are extremely close to having the FL Die in the proper position.

NOTE: The reason for this is because the FL Die has begun Resizing the Case-walls down to the Pressure Ring. As it does so, the Case-body lengthens slightly which in turn moves the Case-shoulder slightly forward. Then as the "Fine Tuning" continues the Case-shoulder makes contact with the FL Die and is moved slightly reward(or slightly shortens the Case-head to Case-shoulder dimension).

7. Stop when there is a slight bit of resistance when closing the bolt on the empty case. You now have a "slight crush fit" for the case in that specific chamber, or Zero Headspace.

8. Once you get it where you want it, take some masking tape or a black marker and put a Witness Mark where the FL Die Lock Ring is positioned to hold the FL Die in this position. Loosen the FL Die and return the Lock Ring to align with the Witness Mark and sung up the Set-Screw.

Screw the FL Die back into the press and try squashing another case. It should have the same resistance as the previous one. If not, you need to re-adjust the Lock Ring so it does. But you are extremely close to where you want it, so make very small changes at this point.

Occasionally check the fit of the cases in the chamber, say every 5th firing just to make sure nothing has slipped. Checking more often won't hurt anything and give you confidence that the Set-Up is still proper.

 

[Bart B.]

steve4102 says:

7. Stop when there is a slight bit of resistance when closing the bolt on the empty case. You now have a "slight crush fit" for the case in that specific chamber, or Zero Headspace.

I asked Sierra Bullets about this very thing many years ago. Their man who tested virtually all of their bullets for accuracy as well as developing reloading data said they never got good accuracy with a crush fit; belted or rimless bottle neck cases. Sierra always set the shoulders back a little bit. I later learned that none of the folks winning high power matches setting records once and a while along the way never did that either but set case shoulders back, too.

So I quit doing that, got a case headspace gage, set the full-length sizing die to put a sized case shoulder back a couple thousandths from its fired position. A riflesmith catering to folks winning those matches showed me what happens when chambering a crush-fit case in most rifles. With a dial indicator on the bolt head, one can easily see how a crush fit makes it not close to the same place with each shot; a loose fit lets the bolt head position closed quite uniformly on every round. My accuracy with all reloaded cartridges got a bunch better.

As most rifles don't have their bolt face squared with the chamber axis, their slight angle gets impressed on the case head the first time that case is fired. Each time that case is resized to a crush fit, when it chambers the high point of the case will mate someplace around the bolt face and depending on where it touches, binding will occur in different amounts causing the bolt head to align itself someplace different each time in the receiver. Even with squared bolt faces with crush fit cases, binding will still prevent perfect repeatability closing the bolt to the same orientation in the receiver. That small difference causes a bit of inconsistancy to degrade accuracy. Maybe not too much, but noticable to the best shots.

 

[T. O'Heir]

"...fire formed cases..." As in once fired? They fired out of your rifle? If not, you'll have to full length resize 'em first. You can neck size 'em for use in the rifle they were fired out of only.
"...Zero Headspace..." Headspace has nothing to do with the cartridge.

 

[10 Spot Terminator]

Thanks guys and I did end up finding where the case had enough variation to cause the problem. I seems that when using the neck sizing only die on the fire formed cases that the length of the case neck that was resized in relation to the datum line on the shoulder would vary by maybe .002 of an inch . when I backed the full lenghth sizing die off by appx. 1/8 inch and remeasured one case as I progressively worked the die lower and lower being sure to check for any pushing back on the shoulder and attempting to chamber the one case as I went along I found this,,, the very instant every last bit of the neck was sized tight up against the shoulder and no movement measured on the shoulder the case would chamber in my rifle. It would seem that using the Stoney Point ( now Hornady ) collets to measure the cases that they set to far down onto the shoulder of the case rather that right at the junction point of the neck and shoulder where the body of the case first starts to form. As a precaution I set the die down another appx. 1/16 of a turn and was able to detect maybe .0015 of setback using calipers at the datum line and still not a bit of movement with the case comparator. All of the brass feeds smooth as glass now. Will load them tomorrow after Turkey huntin. Thanks for the help guys .