Inconsistent shoulder bump (Starline brass)

[NotBotvinnik]

Hiya-
So I’m cranking out some loads with Starline brass for my 6.5 creeds and I’ve noticed some shoulder bump inconsistencies. Everything else I size is right on the money.... ie Lapua, Hornady, Peterson etc. Fired brass comes out of my rifles @ 1.5250” and I kick it down to 1.5230” running the brass I just listed. However, running the Starline my bump can range from none at all to forty thousandths.

I just can’t figure it out. I can pull that Starline out of the equation.... go back to Lapua and get two thou like clockwork.

I’m using-

Imperial sizing die wax
Redding Type S bushing FL die
Redding T-7 press

Yes everything is nice and snug and my die is set up properly. Thanks for any advice

 

[KZP]

How many firings have these cases gone through?

 

[NotBotvinnik]

The Starline cases are once fired

 

[KZP]

Have you measured 20 or so fired but non-resized starline cases shoulders to see if they are all at the same starting point?

 

[spife7980]

I notice “creeds” was plural. Are these all out of the same chamber?
Keep brass separate to the chamber they were fired out of and I bet you don’t have this problem of you are mixing brass now.

 

[AllenOne1]

If you are seeing variation between zero and 40 thousands you have a big issue and it isn't the brass.

If this is random brass then you would have to check each piece before it was sized and again after to see what is going on but it isn't going to be 40 thousands short and it isn't going to grow by 40 either.

 

[Bradv86]

I could maybe understand .004", but .040" makes no sense..

Even if you have a generous chamber and size it completely I am not sure you would even be able to achieve .040 bump given where the shell holder makes contact with the die.

Is your caliper battery dying?

Trying to resize snap caps?

Even if between multiple rifles, if they all pass headspace measurements I still don't see .040 happening once the shell holder contacts the die.

Give a bit more information on your equipment, process etc otherwise you will likely just start getting a bunch of wild guesses.

 

[918v]

He’s not seeing a .040” variance. It is not possible to induce that kind of variance.