Case Neck Concentricity

The reason I ask is because I have been purposely using a Lee Loader (whack-a-mole) for my .243W and seat the bullets out to 10 thousandths over what is considered standard and have almost zero run out.

My "BR" acquaintance however is consistently plagued with bullet runout issues because he his always seating his loads to just 5 thousandths of an inch from touching the rifling. He's shooting a .220 Swift chambered Weatherby and replaces the barrel every 500 rounds as well. 

The only time I have ever experienced a bullet runout issue with my 303 is when I attempted to seat the bullets 20 thousandths of an inch off of the rifling.  Accuracy was severely affected and pressure spikes were an added nightmare.

I reset everything back to military specs and the accuracy returned with no unusual pressure spikes with abnormal runout becoming nonexistent...

You mentioned that you are, "throwing away" your RCBS FL die? Is there something inherently wrong with it?

I ask because the RCBS .303B FL, Neck, and Seating Dies are all I have been using since I started reloading in the mid 1980's.

Originally, I used just the FL die for everything until my BR acquaintance insisted that I get a Neck sizer with a 7.62 expander ball in place of the original 303 expander. For general purpose work using projectiles without a cannelure, I have stayed with a C.O.L. of 3.075". With a cannelure, I seat the projectile to 3.115". This seats the projectiles just past the cannelure while still allowing for reliable feeding and safe chamber pressures. Case and Bullet runout have never been a primary issue in the nearly 4 decades I have been reloading for the venerable 303 British. Runout became an issue only when the bullet was seated out past safe and prudent tolerances. The truly ironic item here is that I have had absolutely zero issues reloading any caliber I have when using the Lee Loader Whack-A-Mole. Just like that Rotisserie commercial, you just, "Set it and forget it."

You mention the "centerline" of the case being "Off"? 

I can picture that happening after a round has been fired and (before reloading) inside a chamber with an amplitude of "generous" spacing but, even with neck sizing only, the case centerline should never be, "Off." 

I should mention here that,

I had a Hornady Seating Die for my 7.62 that was machined wrong from the factory. It would seat the bullet at an angle that provided the bullet runout you described at the start of this thread which is why I asked about you throwing away the RCBS die and it possibly having a factory defect...

I only use this die to bump the shoulder back, ala partial length resize.  About once every 12 to 15 reloads.  I think the only reason why accuracy is not terrible with it is it sizes the body of the case considerably, increasing the taper such that there is sufficient clearance at the shoulder of the case with the chamber and the bullet doesn’t get too far out of alignment with the bore.  

The new .303 Forester Benchrest die is giving me .002 runout. Much much better. 

I also checked my .223 reloads, and those new Wilson dies (full length bushing sizer and in-line seater) produce very concentric cartridges.  The Dillon dies I was using gave .015 inch runout at the bullet.  They just would not get the 80 gr SMK concentric to the case body.  The difference at the target was very noticeable.  Went from 9 ring to X ring at 600 yds just by changing out these dies. 

A cartridge case concentricity gage won’t fix the problem, but it’s sure a good way find out if case neck/bullet runout is the cause of accuracy issues.  It’s not necessary to check your loads with one, unless you’re having unexplained accuracy problems. Some shooters will use them to sort long range loads and set aside those for matches having runout less than .002 inches. 

Sapper, if you’re getting 1 to 2 MOA, that’s as good as it gets, particularly if you’re shooting with the original sights. 

Yes, after some research, I chose the RCBS gage,  it even checks for case web thinning. I’m very pleased with it. 

Do you use any kind of lube inside the case neck when resizing?

A while back I polished all my expander balls & started using a dri-lube applied inside the neck with a cleaning brush.

The polishing is a "one step & done" thing. I just chucked the shaft in a power drill & spun it till it was mirror-bright in Green ScotchBrite pads. I cut a 1" strip off the narrow side of the pad & squeeze the ball from both sides for the most concentric polishing I could think of.

It made quite a difference to me.