Concentricity with RCBS Competition Dies

[Rol_P]

I have been using RCBS Competition Dies to hand load my 30-06 cases.. My resized Lapua cases in the last batch all were within .001 of concentric before seating the bullet..

I loaded five Partitions and five Accubonds earlier today and final loaded cartridges are from less than .002 out to .005+ out. Only four of the 10 were .002 or less.. out of concentric.

Does anyone on the forum use the Forster or Redding Competition Seating Dies? If you have, what kind of measurements are you getting when checking concentricity of the loaded rounds? How significant is concentricity when looking for accuracy? I have read that .002 or less will produce MOA with a rifle capable.

I like the RCBS open window to place the bullet in, and the collar to center the bullet over the case, but there appears to be too much play in the machining of the collar. Upon examination the points of both Nosler Partitions and Accubonds wabble in the seating stem. RCBS will make a custom seater stem for 17.95 each to take care of the wabble, but I am wondering if a Forster or Redding Competition Seater would be the way to go, even if more expensive.

Thank you in advance.. Rol

 

[kraky]

These questions always open a huge can of worms!
You might be really well off to do a Google search on the stuff.
It's my belief the concentricity by itself does not make an accurate round. Accuracy really comes from how well your rifle likes the harmonics of the powder and bullet. Some guns have a problem with bullets that are a little bit out of round and other guns don't seem to mind them at all.
All that said it's certainly a good idea to try to make as consistent of ammo as you can and any ammo under .003 is probably going to shoot great provided your gun actually likes the load.

 

[NWBlacktail]

I have an RCBS comp seater for my 223 Rem 700. But I only really use it for playing with new bullets. Otherwise I just use standard RCBS seating dies. And I've never ever measured concentricity.

Both my Rem 700's shoot well below MOA, with good bedding and one has a Timney trigger.
My Ruger M77 shoots about 1 to 1.3 MOA, with all factory rifle (not bedded).

Anyway, I think my point is concentricity likely matters when you are trying to get below 1/2 MOA, and your scratching for every last bit of uniformity.

 

[ElmerThud]

I use RCBS competition dies for my .25-06 (essentially the same case as 30-06) I minimise run out because a bigger run out is far more likely on longer cases than medium sized ones and has great effect in undermining accuracy on good loads.

I only ever F/L resize and you can see how on the 'messin' around with press and dies' thread.
It comes down to how carefully you set your die up - in particular the de-cap rod.

Once the concentricity of neck/case alignment is done, care in bullet seating comes next. Even with a competion seating die, it does no harm and potentially some good to 'start' the bullet into the neck, then back off & rotate the case 90-180 degrees and then seat the bullet.

'The F/L resizing die is closely set up on the press to F/L resize to the selected headspace dimension then locked down without the lock nut being too tight & with the 'O' ring in place...The die can then be moved up/down with grips if necessary to F/L resize cases to the exact fired case dimension or certainly within .0005"-.002" range.

Centralising the expander/decapping rod is important..more so on longer cases i.e. 30-06 than shorter cases, but nevertheless should be done anyway. There is a good technique for doing this.

Loosen the de-cap rod then drive a lubed case into the F/L die. As you retract the case, as soon as you feel the expander ball tension in the case neck, tighten the decapping rod locknut before retracting the case from the die further. Your case neck/case body concentricity should then be as good as it gets'.
ATB ET

 

[Oldtrader3]

I don't much care for RCBS decapping stems and bullet seating stems. I get .001/.002 TIR max (most .001) on all loaded bullets with the Forster dies and carbide stems. Forster's seating die is more accurate and better made than RCBS as well.

 

[257 Ackley]

Get a Wilson seating die for the best chance of Great concentricity.

 

[ElmerThud]

Get a Wilson seating die for the best chance of Great concentricity.

Joel these dies are so damned expensive in the UK - even RCBS dies & especially competition dies are pretty pricey....but hey, we have to use something and since my dies were bought so many years ago and by & large have produced decent enough ammo. I'll just carry on doing it the old fashioned way :roll: LOL

I suppose if you're starting off reloading a new cartridge it may be best to buy the modern up to date dies from the outset...but me, I'm old now and really only shoot hunting rounds.
Stay well, ATB ET

 

[PJGunner]

I only have one set, It's for the .308 Win. I use it mostly for the cast bullet loads I shoot. I've gotten one load that if the wind isn't blowing too hard will do 1.5 MOA at 200 yards. I even got that load to shoot 2.5 MOA at 300 yards but that was on a totally calm morning. I don't even know if I ever want to try a see if I can do that again. :lol: Probably was more luck than anything else.
Paul B.