Loaded ammo bullet runout???

[redgun]

I am using a RCBS Rockchuncker press w/ Redding comp seating micrometer dies (7 WSM and 6BR, loading Berger VLD's in both) and getting bad runout on the loaded ammo. I have already added VLD seater stems to both dies.

Brass on both has been neck turned and being resized with Redding neck bushing dies.


Any suggestions as to what part of my equipment could be to blame/need replacing??

 

[Outlaw6.0]

That depends...


Where is your run out occuring? At the bullet OR at the cartridge neck? That is the question...

 

[redgun]

Where is your run out occuring? At the bullet OR at the cartridge neck? That is the question...

Hmmm, good question.

My runout tool puts the dial indicator on the bullet, so I have never been able to check the necks (say after sizing).

 

[Outlaw6.0]

That is kinda what I was thinking too... I fell into that trap as well.


Most of the "uber" runnout I've seen can be tracked back to the case neck. I usually suggest switching to the Bushing style dies... but you already have those..


I'm guessing you have the Hornady (or similar) Bullet run out guage?

 

[Broz]

Do you have an expander ball on the depriming stem? If so I remove it when neck sizing with a bushing die. Also after neck turning you may need to fire the brass in the rifle to get things back on track.

Jeff

 

[redgun]

I'm guessing you have the Hornady (or similar) Bullet run out guage?

No sir. I forget who made the ones I have, but they are actually runout "correcters".

Picture an aluminum block. A loaded round goes in the top (these blocks are caliber specific and fit very snug) and is spun with your fingers. A dial indicator goes in from the left side and rides on the bullet tip. There is a threaded "screw" on the other side (with a pivot point where it touches the bullet) with a large knob.

You spin the shell by the case head & find the high and low spots. Put it on the high spot, screw in the "correcter" and actually straighten out the runout.

Pretty slick little tool, but there is no way to move where the dial indicator rides (I can't adjust it to ride & check the case neck).

 

[redgun]

Do you have an expander ball on the depriming stem? If so I remove it when neck sizing with a bushing die.

Yes, the expander is still attached on both sizer dies. I can take one of them off & check that.

Also after neck turning you may need to fire the brass in the rifle to get things back on track.

The brass (for both rifles) has been fireformed since neck turning.

 

[Ludicrous]

How much runout are you getting? I measure different runout on almost every load before correction. Some have zero, others a couple thousands out. I'd prefer that than measuring the EXACT same runout measurement on every load. That would drive me crazy looking for the cause. Anyone always get zero runout on every load?

 

[Boss Hoss]

Mine is not far off but my equipment is a little different from most folks. Is is possible to achieve this but it is not going to be easy or cheap.. Have to plan ahead---on factory guns this is pretty much a waste of time because the chambers are pretty sloppy. Does not really make that much difference on those.

Make the dies when reaming the chamber..

 

[redgun]

How much runout are you getting?

.005"-.020" on the 7WSM w/180 gr Berger VLD

.005"-.010" on the 6BR w/105 gr Berger VLD

 

[Bart B]

Mine is not far off but my equipment is a little different from most folks. Is is possible to achieve this but it is not going to be easy or cheap.. Have to plan ahead---on factory guns this is pretty much a waste of time because the chambers are pretty sloppy. Does not really make that much difference on those.

Bottleneck cases headspacing on their shoulder align bullets in the front of the chamber equally perfect up front in all chambers. Doesn't matter how the fired cases are resized as long as there is at least .0005" clearance around the case.

Get rid of that expander, deprime cases before cleaning them then use a bushing 3 or 4 thousandths smaller than loaded round neck diameter.

Bullets don't need runout under 1% of bullet diameter.

 

[rscott5028]

Please post a photo of your runout gauge in operation.

I think you said that your indicator rides on the bullet "tip". I don't recall seeing one like that. It seems like a precarious way to measure with multiple angles converging rapidly.

Most runout gauge indicators ride the bullet shank just ahead of the case neck.

-- richard

 

[Mikecr]

.005"-.020" on the 7WSM w/180 gr Berger VLD

.005"-.010" on the 6BR w/105 gr Berger VLD

With this much runout, I suspect there is something seriously wrong with the measurement.
No way it's actually that far out..

 

[Bart B]

10 thousandths bullet runout measured at the bullet tip's quite a bit, but entirely possible if the case neck's bent out of alignment with the case body axis. I've seen that happen when expander balls have to move a lot of brass sized down quite a bit in a FL die.

Bullet runout measured right in front of the case mouth with the case pressure ring in a V block and bullet tip held in a dead center will be less than if the case pressure ring and bullet right in front of the case mouth are in V blocks and the dial indicator on the bullet about 1/10th inch back from the tip.

The best runout readings on bottleneck cases that headspace on their shoulder happens when the case pressure ring rides in a V block and the case shoulder datum point spins in a dead center with the dial indicator on the bullet about 1/10th inch back from the tip. Such cases align themselves in the chamber this way when they're fired; pressure ring's against the chamber wall opposite the extractor and the case shoulder's perfectly centered in the chamber shoulder from firing pin impact. I've oft times thought about making some drawings showing how a bottleneck case held different ways in a runout guage gives different readings for the same loaded round whose bullet axis is 1/6th degree off the case body axis.