How Does Case Diameter Affect Barrel Life?

[TScull]

Will a long narrow (small diameter) case result in a longer barrel life than a short fat (large diameter) case of the same capacity? (Assume both cases drive an identical bullet to the same velocity.)

My thinking is along the lines that the long case may delay ignition of the portion of the powder furthest from the primer with the potential of lower peak gas temperature and a corresponding increase in barrel life.

What have your experiences been?

 

[mikecr]

I don't know for sure, but I'd think a short-fatter-steeper-shoulder case would produce best barrel life.

My thinking; More powder burnt inside the chamber instead of traveling(and burning) in the bore.

And opposite;
A powder slug would add to recoil, carbon, decrease efficiency, and contribute to excess muzzle pressures. I can picture it blasting the throat like a cutting torch, and impinging into the bullet base and crown face on exit.

 

[J. Valentine]

My experience has been that it don't make enough difference to identify it from any of the other reasons why barrels wear out.
There has been theories about steeper shoulder angles containing the blast better but most improved designs are run flat out anyway because thats why they go to an improved design in the first place .
So any possible benifit may be wiped out by higher chamber pressures , extra powder abrasion etc. of the improved design.
You would have to run two identical rifles , one chambered in a improved larger case diameter version of the other and load to the same chamber pressures or maybe same velocity in both guns.
Then shoot and clean them identicaly until wear becomes obvious to maybe see a difference .
I have found that moly coating is more useful at adding extra barrel life rather than anything else I can identify. Good quality barrels , correct cleaning and reasonable load pressures not withstanding .