Thread: Case Neck runout with redding type s bushing die

Using new RCBS single stage summit press and getting roughly 3-6thou case neck run out after re sizing..any idea why ?


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Give the die a little bit of float using an o-ring. The Lee lock rings are good for this. Give the bushing a little bit of float by not screwing the plug down on top of it hard. Anneal and neck turn the brass.

They seem to work well with custom tight necked chambers. A bit hit and miss on factory chambers sometimes. FL dies don't do this.

Originally Posted by Pommy

Give the die a little bit of float using an o-ring. The Lee lock rings are good for this. Give the bushing a little bit of float by not screwing the plug down on top of it hard. Anneal and neck turn the brass.

They seem to work well with custom tight necked chambers. A bit hit and miss on factory chambers sometimes. FL dies don't do this.

Will suss some lee lock rings thanks for that! Its for 300norma mag


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Originally Posted by Pommy

Give the die a little bit of float using an o-ring. The Lee lock rings are good for this. Give the bushing a little bit of float by not screwing the plug down on top of it hard. Anneal and neck turn the brass.

They seem to work well with custom tight necked chambers. A bit hit and miss on factory chambers sometimes. FL dies don't do this.

I agree...my chambers are all tight requiring neck turned brass, and Redding S type dies with loose bushings just can't and never produced zero runout on the necks.......FLS first and then if you have too deal to the neck size. I have seen a Hornady FLS die with standard expander button produce excellent zero runout every time and that is on Bertram brass with up to 0.001" neck wall variation so it is not a dream to have zero runout.....!

To measure neck runout is very difficult as well so be sure you actually have a neck that is not concentric with the body as distortion of the body can produce a false negative. Not sure how you are measuring runout but it is imperative the body of the case is running true on bearings of your gauge by indicating on the radial line of support first before the neck. Better still is to machine a mandrel on the lathe and press your cases onto it......you will soon see if you have runout then.

Is the run out there before sizing?

Originally Posted by chainsaw

Is the run out there before sizing?

New norma brass is about 1-2thous. Once fire formed 0-1 thou!


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3-6 thou I wouldn’t worry about it if the loads are accurate

Is the bush able to move slightly in the die so it can center on the neck?

If there is more than 5 thou difference between your fired case neck outside diameter and the sized case then Redding suggest you use more than one bushing.

I had this same issue when sizing for a 6.5x55, fired were .299" and sized are .291 and I experienced runout. Once I sized in two steps the runout dropped to around. 001".

Originally Posted by Tech

If there is more than 5 thou difference between your fired case neck outside diameter and the sized case then Redding suggest you use more than one bushing.

I had this same issue when sizing for a 6.5x55, fired were .299" and sized are .291 and I experienced runout. Once I sized in two steps the runout dropped to around. 001".

Ill do some measuring. Thanks for that!


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Do you neck turn or not? What is the inside neck run out?

Originally Posted by Friwi

Do you neck turn or not? What is the inside neck run out?

Havnt actually measured ID.. nah maybe i should be neck turning tho


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Another thing you can do is half seat the bullet then raise the ram and turn the case 180deg then finish the seating.

Was getting similar result with my type s die, 3-4 thou was common and that is neck turned and then annealed.My competition redding die was no better. Tried a redding FL die and that was more often in the 1-2 thou range and surprisingly running an expander mandrel through after sizing had no effect on runout

Originally Posted by Waimauku

....My competition Redding die was no better.

@Waimauku, could I ask please if you ever found a way to get improved runout from either your Competition or FL Bushing dies?
Although the design of the competition dies is intended to remove misalignment introduced by the press, I have found this not to be the case, and traced unexpected runout back to the shell holder. Perhaps the case-to-sleeve fit is poor?
Has anyone considered running their chamber reamer into the sleeve?