Case length growth Q:

[bow shot]

1) Savage 6.5-284, factory, new.
2) Measuring with Hornady case length gauge and Fowler NKS caliper (i.e.., measuring what we commonly call head space, not trim length)
3) Laupua brass
4) Length of brand new brass before firing: 1.800" (+/- 0.0005")
5) Length after 2 firings: a bump down to 1.805" is required to close the bolt without resistance (firing pin removed)
6) Bumping is done with Hornady FL die, shimmed up with Skip's Shims to achieve "good" bolt closing (no resistance turning bolt down)

I see that my cases grow over 0.005" after fire forming.

The question: is this degree of case length growth unusual?

 

[300 RUM]

It really depends on your chamber. I would say perfectly normal.

 

[Shynloco]

Normal growth for a 6.5x284. Even 6.5X55 do much the same. I've encountered that and a bit more in mine during fireforming and even subsequent firings. 6.5's create real pressure and love to eat barrels as many have experienced and written about. Nature of the beast I'd say. Just my thoughts.

 

[bow shot]

Thanks folks. I hadn't had cause to measure such things till lately (lots of boring reasons…).

Anyway, you know how it is: You measure something that you never measured before, and go "huh.. I wonder if that's normal"

…especially when it involves something that can tear your face off if it isn't "normal"