Bushing die increasing run-out

[IAHNTR]

Fired cases run within 1 thou of run-out. After running through my Redding Comp. Neck Bushing sizer the run-out is increased to around 3 thou. The bushing is loose and rattles if I shake the die. This is a relatively new die and bushing, less than 100 rounds sized.

Is this normal and if not what should I try?

I took the die apart and cleaned with no effect.

 

[Trickymissfit]

Fired cases run within 1 thou of run-out. After running through my Redding Comp. Neck Bushing sizer the run-out is increased to around 3 thou.

Is this normal and if not what should I try?

I took the die apart and cleaned with no effect.

been saying for several years now that sizing a case, and at the sametime neck sizing with a bushing is asking too much for the die to do. But alas it might simply be a die alignment problem, or wear in the press.
gary

 

[IAHNTR]

I'm pretty sure this die just deprimes and sizes the neck to the 0.309 bushing size. I was using this die in an older Lee press so will try it in the rockchucker after my next time out.

 

[TOM H]

Fired cases run within 1 thou of run-out. After running through my Redding Comp. Neck Bushing sizer the run-out is increased to around 3 thou. The bushing is loose and rattles if I shake the die. This is a relatively new die and bushing, less than 100 rounds sized.

Is this normal and if not what should I try?

I took the die apart and cleaned with no effect.

Are you using expander if so they should of include a decapping pin retainer may want to try that.

 

[IAHNTR]

No expander ball/plug, just a decapping rod that screws into the micrometer head.

 

[Mikecr]

Sometimes reducing runout is trial & error, and another press might produce better results. Sometimes reducing runout means measurement to find the root cause.

It is normal for the bushing to float(by design). A press can cause some runout as well.
The main cause of runout is thickness variance in the cases. This is concealed with fire-forming, and brought out again and again(often worse each time) with sizing, because differing thickness springs back differently, and sizing is adding energy to it.

Other contributers to high runout are poor case design, poor chamber design, and of course excess sizing.
Loaded runout(as measured off bullets) can jump dramatically with a seating problem.

 

[Bill Johnson]

The main cause of runout is thickness variance in the cases.

That's what I've found. Wall thickness in the necks can and does vary if the necks are not turned (or you have Lapua brass) as much as .006 one side to the other.

When the case is fired, the neck expands all the way around until it contacts the chamber, then it contracts slightly, so the unequal wall thickness doesn't show on the outside.

 

[AZShooter]

You can always talk with Redding. 607-753-3331 Unfortunately they are close the week of Thanksgiving.

 

[LBZ]

It is normal for the bushing to float in the redding die. However not all bushings are concentric. It may also help to float the die on a #17 rubber O-Ring to help with any press miss - alignment.

 

[IAHNTR]

It is normal for the bushing to float in the redding die. However not all bushings are concentric. It may also help to float the die on a #17 rubber O-Ring to help with any press miss - alignment.

So you put the o-ring on the top side of the press and then just snug it down a little? - Thanks

 

[Lost creek]

I have the same problem with neck and full length bushing dies. Adjust so the bushing does not size most of the neck. I only size about 1/2 the neck and can keep runout about 1/2 thousands.

 

[Greyfox]

Fired cases run within 1 thou of run-out. After running through my Redding Comp. Neck Bushing sizer the run-out is increased to around 3 thou. The bushing is loose and rattles if I shake the die. This is a relatively new die and bushing, less than 100 rounds sized.

Is this normal and if not what should I try?

I took the die apart and cleaned with no effect.

The looseness of the bushing can be controlled by adjusting the upper portion of the dye. While a very slight looseness is preferable, too much may cause the bushing to be cocked when sizing and cause runout. I set my bushing by tightening all the way, then loosening just enough to hear a very slight click when shook. I also lube the case necks when neck sizing. Most of mine give me .001" of runout.

 

[Bill Johnson]

By sure the bushing is installed with the numbers down, as well as slightly loose.

 

[LBZ]

So you put the o-ring on the top side of the press and then just snug it down a little? - Thanks

Correct. the O-Ring should fit on to the die just below the lock nut. You will of course have to re-adjust your die.