Bullet runout and seating dies

[jerrya]

I have been using Lee seater for my 270. I checked with a Sinclair concentricity gauge and my problems are happening at the bullet seating phase. I have .001" or less runout after sizing. Would a Forster ultra seater help with runout?
I should have been a bit clearer, after seating my runout is closer to .008"

 

[BCBRAD]

I too use a Lee seating die for a 7mm08 and TIR is 0.001" as well. I also have several Forester competition seating dies and TIR is ~0.0005 or less.

The 7mm08 is a deer rifle, that gets range use and works well to 1000+ yards, while the others are Benchrest rifles.

 

[bigedp51]

The Forster and Redding benchrest seaters do not allow the bullet to tilt during seating. I have the Forster sizing and seating dies for every caliber I have.

 

[Cameron SS]

I use a redding competition bullet seating die and have never seen the seating process affect the runout that was present before seating.

 

[bigedp51]

Reloading: Seating Die Runout
Seating Die Induced Runout - A Comparison
by Germán A. Salazar
http://www.uniquetek.com/store/696296/uploaded/Reloading-Seating-Die-Runout.pdf

NOTE, both the Redding and Forster seater dies have the same design. Meaning the die chamber holds the case and bullet in alignment.

 

[Tokay444]

If you’re not measuring runout on the empty case inside the neck, there’s no point in measuring runout on the case itself.
Use a mandrel after neck sizing to push the irregularities to the outside of the neck, giving you better concentricity on the bullet.

 

[1-trident-1]

Reloading: Seating Die Runout
Seating Die Induced Runout - A Comparison
by Germán A. Salazar
http://www.uniquetek.com/store/696296/uploaded/Reloading-Seating-Die-Runout.pdf

NOTE, both the Redding and Forster seater dies have the same design. Meaning the die chamber holds the case and bullet in alignment.

thanks for the read.

 

[bigedp51]

If you’re not measuring runout on the empty case inside the neck, there’s no point in measuring runout on the case itself.
Use a mandrel after neck sizing to push the irregularities to the outside of the neck, giving you better concentricity on the bullet.

If you measure the neck thickness variations with the gauge below you simply subtract the thickness variations from your neck runout.

And if you neck turn, case neck runout is even easier to measure

This gives you a method for setting up resizing dies for minimum neck runout and finding out where the runout starts.

Below if you have .002 neck thickness variation, you simply subtract .002 from your case neck runout figure for the amount of neck runout.

 

[jerrya]

Thanks guys. I wasn't considering that the irregularities would be inside the neck of the case.

 

[BCBRAD]

Thanks guys. I wasn't considering that the irregularities would be inside the neck of the case.

They are when you use a bushing.

 

[bigedp51]

The Redding bushing die FAQ tells you if you do not turn the necks and the neck thickness varies .002 or more to use the expander that comes with the Redding bushing dies.

The U.S. Army states that match grade ammunition should have .003 or less bullet runout.

And when you full length resize, the case body has no guiding or alignment effect on the bullet in the throat. The rear of the case is supported by the recessed bolt face. And in the front by the bullet in the throat. So remember when checking neck and bullet runout and rotating the case on the case body that when chambered the case body is not touching the chamber walls.

Below Kevin Thomas worked in the Sierra ballistic test lab and now shoots for Team Lapua USA.

 

[redryder]

BigEd knows his shtuff!