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 ?


Sent from my iPhone using Tapatalk

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.

Is the run out there before sizing?

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".

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

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


Sent from my iPhone using Tapatalk

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


Sent from my iPhone using Tapatalk

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!


Sent from my iPhone using Tapatalk

Originally Posted by chainsaw

Is the run out there before sizing?

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


Sent from my iPhone using Tapatalk

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

Cheap & cheerful way is to buy a, Lee collect neck sizing die, and even after FLR use the lee die & turn the case 180degrees, give it a double tape. Works well for me.

Might pay to check neck thickness variation too. You may have a couple of thou here that's showing up as runout. Turning necks will clean this up.