I am neck sizing my 280AI cases, in a redding bushing die. Before the cases go into the die, they are less than .001" out around the neck. Once they come out of the die, they are over .002" out around the neck. What is going on with this die? What could be the problem ?
I have cleaned the necks very well, and lubed them. The press is a rockchucker if that matters.
Posts: 1496 | Location: behind the crosshairs | Registered: 01 August 2002
JustC: The expander ball is probably the culprit. Several things you might try:
1) Take your expander ball/stem out of die and put in drill or drill press. Use 400 emery cloth or crocus cloth to polish the ball. The higher the polish, the less friction.
2) Slip an o-ring over the threads (under lock nut) of the exp. ball stem and adjust so that the ball is as high as you can get it but be sure it is not within the neck sizing portion of the die. This will, hopefully, allow the expander ball to enter the bottom of the neck before the case neck exits sizing area of die. Do this before tightening the lock nut so as to hold ball centered in case while tightening lock nut. Once lock nut is tightened, the o-ring will allow very slight movement of the stem to self center within the "slop" in threads present in all dies.
3) Lubrication of inside of neck is extremely important to case concentricity. Imperial dry neck lube is excellent....graphite works well, also. Easily applied w/Q tip.
JustC, The usual problem is the die itself. Neck sizing dies have more case body clearance than full length resizing dies. The case is not supported solidly enough for the expander ball NOT to have an influence on concentricity of the neck. The expander ball can actually pull a neck out of concentricity. One way to solve the problem is to remove the expanding ball when sizing the neck and reinsert it after the neck is sized, but leave it loose enough to conform to the neck, rather than vice versa. It's a pain in the drain, but case neck concentricity probably has more affect on tight groups than anything else. If simpler remedies fail, this trick usually works.
Posts: 529 | Location: Missouri | Registered: 31 January 2002
Follow the advise as posted above. There's one more thing to try, though, assuming you're using a press and not hand dies : squaring the dies in the press. Threads on dies being of a rather sloppy fit, it helps to put a washer on top of the shellholder to apply firm upward pressure against the base of the die (you will feel the slack being taken up), while locking the ring. I've done it with all my dies and in some cases, it did a remarkable job in eliminating case neck run out.
Posts: 2420 | Location: Belgium | Registered: 25 August 2001
quote:Originally posted by Andr� Mertens: Follow the advise as posted above. There's one more thing to try, though, assuming you're using a press and not hand dies : squaring the dies in the press.
What brand of dies do you use? I was able to do this with Lee dies due to the rubber O-ring under the locknut, but with Redding dies all I get for my trouble is a loose locknut.
John
Posts: 1246 | Location: Northern Virginia, USA | Registered: 02 June 2001
I use several brands, incl. Redding dies and with the latter achieve .001" runout. A loose locknut may mean a stucked pellet under the screw. Take out the screw and tap the ring to loosen the pellet. If it doesn't loose up yet, try tapping inside the screw hole with a punch to get the pellet to the bottom. Start the procedure again and all should be fine.
Posts: 2420 | Location: Belgium | Registered: 25 August 2001
