Premium Brass (Peterson) not getting longer

[Bat Rastard]

I am new to the better brass. I have fired this batch of Peterson three times now and it does not need trimmed. It has only grown .002-.003. Is this common, because it is thicker?
It is 6.5 Creedmoor. I only neck sized the first two loadings, so I think that helps not stretch the cases, but this seems too good to be true!
Any thoughts ?

 

[Varminterror]

It’s growing, it’s just growing slowly: 2-3thou in 3 firings isn’t bad. With a minimal required (2thou) bump or neck sizing only in dies well matched to a chamber, it’s not so uncommon. Alloy resilience and hardness are factors, but I’d chalk it up to the dimensional alignment of chamber and dies more than anything.

I always end up trimming anyway.

 

[AJC1]

Brass composition and load power along with sizing technique all effects growth. If your not growing fast that's good...

 

[Bat Rastard]

Brass composition and load power along with sizing technique all effects growth. If your not growing fast that's good...

I am not complaining! I just have never experienced this phenomena before.

 

[markr6754]

I think this falls under the "Looking a gift horse in the mouth" clause.

 

[Allen One1]

I'm using Starline brass in 6.5 Creedmoor and am seeing little to no growth as well. It gets check each time but nothing is getting trimmed off. I do deburr it each time and I think this may be removing enough material that I don't see the growth.

 

[Armorer 101]

In my experience with brass growth, the quality of the brass has little to do with growth. The major causes are the chamber cut, head-spacing, the sizing die cut, matching the chamber, and the load pressures. Running neck sized properly setup brass at lower pressures will make your brass last a long time. Brass stretching is a major cause of short brass life for a reloader.

Example is a bench rest shooter. They fire one case only, over and over again to maintain the exact same parameters. That one case is reloaded again and again at the bench, at each shot. Any changes to the case are controlled by proper machining and pressure.

 

[Walkalong]

Brass flow is caused by pressure. A better fit helps stop stretching in the middle of the case. Head Clearance (fit) makes a difference because the case head will always be blown back the the breech face, causing stretching in the middle. A better fit helps stop hardening as well.

So, fit & pressure, then the brass alloy used/condition/softness of the brass.

 

[Bat Rastard]

A fired case measures .001-.0015 on my RCBS Precision Mic . All the theories presented match up.