Adjusting dies for trueness.

[Airgunner7]

I just got one of those Hornady bullet concentricity measurers and noticed my bullets are ALL about 2-3 thousands off center. Do you think it is something correctable with rcbs brass neck sizer or bullet seater dies and how would a guy go about it?

Thanks

 

[boomtube]

I'm sure you understand that the only adjustments for the dies is to screw them up or down, neither of which will influence run-out. But, something can be done; get a Lee Collet Neck Sizer and a Forster BR or Redding Competition seater.

Actually, if you are refering to Total Indicated Runout, what you're getting now is quite good.

 

[flashhole]

Not true. There is enough lateral play in the die and press threads to get a fair amount of movement. What I do to true the die to the press is take a known straight/concentric case and run it up into the die before I lock it down in the press. The technique works for both the sizer and seat die. As simple as this sounds it really goes a long way in keeping runout to a minimum.

 

[Gene]

I think .002 - .003" TIR is pretty good. I check mine regularly on a Hollands concentricity guage, and that is about as good as it gets. Above .006" would concern me. I would say, do nothing. But if you are really anal about it, try placing a 7/8" O ring under the die. Tighten the die down but not excessively. This will allow the die to adjust to the case dimensions as it is sized or seated.

 

[Hairtrigger]

I guess the application is reasonably important here
Hunting rifle, Varmints? Benchrest?

 

[Mikecr]

Gene, he isn't measuring runout at all, but concentricity. Concentricity gauges mask most runout as the ends are pinned stationary.
For example, 1thou off concentric over a case body length could measure 12thou TIR off a seated bullet bearing. But he'll never see this...
So 2-3thou 'off concentric' likely means more in actual runout. And I'm sure he can see his bullet tips wiggling all over hell with loaded rounds rolling across glass.


The ONLY ways he'll fix this:
1. Buy & use a RUNOUT gauge, and BALL MIC.
2. Cull brass for least thickness variance.
3. Setup dies to size the very least he can get away with(NOT FL).

He can do every other DIY trick in the book, and his loaded rounds would still go unmeasured as straight.
Does it matter? Probably not. In this regard I agree with you.
It's considered or ruled out as an issue when performance is poor.
But we shouldn't confuse concentricity numbers with TIR here.

 

[boomtube]

"I guess the application is reasonably important here Hunting rifle, Varmints? Benchrest?"

Air Gunner's runout/concenticity is the same no matter what he will use it for. He didn't ask us how much it matters, he just asked our opinions for reducing it.

My opinion is that carefully conceived methods of "adjusting" dies in the threads do nothing unless the press is horribly out of alignment to start with and then only if the die is locked down hard with pliers or a wrench. Finger tight/snug is all any die needs to be secured. The O ring thing can fix that, it's why Dick Lee decided to use that kind of lock ring.

 

[Airgunner7]

O ring it is then.

I do tend to lock em down tight(with pliers lol)



Can't see any runout while rolling them but, every little bit helps.


Thanks



I'll b hunting varmints off my portable benchrest.

 

[flashhole]

O ring it is then.

Thanks

You might be better off just buying some Lee Die Rings with the O-ring. It is recessed to contain the ring.

 

[boomtube]

"Can't see any runout while rolling them ..."

If runout is visible while rolling it's HORRIBLE! It's the last few invisibile thou that are really hard to get rid of.

I haven't found the o ring to be greatly helpful, just spin the dies in by hand and make them snug, they tend to center themselves when sizing/seating pressure is applied.

 

[Airgunner7]

I used a set of lee dies only once, went running back to rcbs...

Kinda funny, the guy at the local reloading shop said "one guy here uses them and swears by them"....makes me wonder about that statement now.

 

[boomtube]

I dunno what you didn't like about your Lee die or what you think is so great about RCBS dies but if you think big green is always perfect, or even better on average than Lee, you will eventually be disapponted. I have and have used dies from every maker for a long time, and tried borrowed dies too. Tested many of them for effect and tolerances. Find there is about as much difference between dies of the same brand as between brands.

Seems there are two grades of dies. Forster and Redding are tied for best because of their superiour designs. All the rest are tied in second place for how well they work. We may LIKE some brands features or how they look better than others but that's only personal preference, not quality of function.

 

[Airgunner7]

After the third stuck case I gave up that's all. I really liked the features of lee but, I had never had a stuck case till the lee...even with one shot lube.

 

[BigJakeJ1s]

Threaded dies floating in threaded press holes will tilt when they float laterally. You're better off making sure the shell ram, shell holder and cartridge case can slide around a little to align with the die (i.e. some polishing and lubrication). Even more importantly, pause at intervals on the way up and down in the stroke, to take the pressure off and allow things to re-align. Or use a press such as the co-ax that does not shift alignment during the stroke like conventional presses do, and allows the die to float laterally without tilting.

Also, different types of lock rings affect initial alignment. It is virtually impossible to get a set-screw lock ring locked in place square on the die body. The set screw forces the lock ring off-center to the die body, which then forces a tilt as soon as the lock-ring & die are tightened in the press. In this regard, the Lee O-ring system is better, but the Forster/Hornady cross-bolt lock rings are better yet. They lock in place securely and squarely. The lee lock rings are too easy to move out of adjustment while swapping dies, and the compression of the o-ring makes it difficult to repeat the exact same depth of the die in the press.

Andy