Keeping Neck concentricity under .001?

[AWLEAPHART]

Hello everyone,
I was hoping someone had a trick I don't know about to help keep neck concentricity down. I had a .284 build awhile back and it was chambered with a standard .284 reamer. Loaded round being .312 and a fired case being .320 at the neck. Its a lot to size down Approx:.008. I only have about .0005 to .001 of neck tension on a loaded round. I was thinking that my bullet runout would be less if i put more tension on the bullet but the neck run out about .002 is coming from resizing. I am using a Redding FL Die and a Wilson Seater with the VLD Steam. I am noticing a flyer out of my normal grouping of about 4" at 500 yards. Can't seam to pin it down. I'm thinking its Runout. Some bullet run out is around .007. Thanks for everyones help. Have a nice spring break.
Anthony

 

[Aussie Denis]

A good start is to make sure that your press ram is clean and lubed and the shell holder is clean and gunk free. Then, don't lock your dies down, free float them. Run the die down to the locking nut and back it off a beez dick, "JUST" so its not locked and you can easily wriggle it ever so slightly with your fingers.

What press are you using?

Haveyou been locking your dies down firmly?

 

[AWLEAPHART]

I have an older RCBS Chucker but I also have a Smaller RCBS press thats about 2 years old.

 

[Clod-NC]

Hi Anthony,hi Denis

Denis,your" beez dick"flop adjustment on the die just cracked me up,this is so typically OZ mate....Thanks for that one.Anthony to complement Denis advice I would suggest you put an O ring under your stop ring when you screw it into your press,and don't overtighten it,just finger normal tight,I mean don't break your finger on it,you have to feel your die sort of wobbling a bit when you're done,it helps the die to self center once a case is fed into it....The other thing you must try is a 2 stage sizing;let me explain.Ram your press up with a case in the shell holder only half its normal course for this caliber,then back up all the way,easy on the ram,don't break your wrist if you know what I mean,then turn you case in the holder half a turn(180°),and ram up again but all the way this last time.Normally,logically would be a better word,the second shot should anihilate the "bad forming"of the first,being its exact opposite physically.I hope it helps.Keep us updated,good luck to you.

 

[PALarson]

Let's change gears, Best way to lower runout is to use Wilson Bench rest seaters and a arbor press, they reduce runout to .000 to .002 in most cases. No press mounted seater that I have ever seen is that good.
Paul Larson mid range long range High Master

 

[mikecr]

The root cause of runout is case thickness variance. Sizing converts this variance to runout.
The more of either variance/sizing, the greater the runout.
Since you're now stuck with excess sizing, the only improvement option is reduced thickness variance.

 

[Rust]

.008 is a lot to size down, the previous suggestion to half stroke when sizing can help, but once again .008 is quite a lot.

As Mike mentioned, you'll want to check your brass for neck thickness variation and toss the ones with over .003" and turning them just enough to clean them up to about 80%. There really isn't much sense in going past that with the amount of clearance in your chamber.

Runout can be reduced by short stroking when seating bullets too, seat it halfway, back out, rotate the case 180 and seat it the rest of the way.

To be honest, I've seen no real improvements using a Wilson seater setup compared to either Redding or Forstner bench rest micrometer seating dies in either 6.5 X 284 or .308. Very rarely are bad runout numbers attributable to just the die.

Another thought, check your case runout on an unfired round, find one that's pretty good, and check it again after it's been fired. The chamber could ne contributing to the problem.

Just keep in mind it might not be a single thing, but a cumulative effect.

 

[CdnHotshot]

Lube the outside case neck and extra lube inside of your case neck ...a simple task often over-looked.
Any extra RAM "pressure" or "jerking" will result in poor concentricity.
I would not blame my RCBS Rock Chucker press.
All my dies are REDDING products
I'm loading all these without issues 17Rem. 260Rem. 223Rem., 22-250AI, 20BR, 20PPC, 308, 325wsm

 

[DennisH]

Wilson Bench rest seaters and a arbor press

Above is the best move I made. I use the Wilson with my BRX and 284. I also have one for my 308, I notice the biggest difference with the BRX and 284.

Lube the outside case neck and extra lube inside of your case neck ...a simple task often over-looked

I also feel the above is very important when sizing your brass.

Biggest problem is cleaning afterwards. Either use Denatured Alcohol or an UltraSonic cleaner, makes it easier, the alcohol flashes off quicker.