rifling depth on accuracy/velocity...

[IdahoSharpshooter]

Using the standard .300/.308" dimensions on a thirty caliber barrel as a base, have any studies shown a velocity or accuracy change (read:improvement) by decreasing the rifling depth?

IE, going from .004" rifling depth to .003" or .002" or even .001"?

Rumors were rampant that one way Wby got such velocity numbers was by using shallow(er) depth of rifling, or even smooth bore reference barrels back in the old days.

 

[JRS]

With Roy Weatherby, it was all about bigger cases with more powder capacity, and lighter weight bullets. He believed the combination was ideal for flat shooting, hard hitting power needed to create enough hydrostatic shock to kill animals quickly and humanely, starting with the 220 Rocket. He made believers out of Elmer Keith and Jack O'Connor, whom at the time, believed heavier slow moving bullets were the ticket.

Shallower grooves were intended to be used with paper patched bullets.

Speed kills

 

[Kurz]

have any studies shown a velocity or accuracy change (read:improvement) by decreasing the rifling depth?

I'm sure someone, somewhere, sometime, has tried to create a study of this but ran into the same problems everyone else has; there are too many variables in making rifle barrels to be able to compare them accurately.

Bartlein makes a .30 caliber 0.299"/0.308" routinely. This goes right along with their 0.300"/0.308" bore/groove barrels. "Boots" Obermeyer makes several variations on the bore/groove relationship. John Krieger has done the same with his Palma barrels.

 

[swd]

Weatherby's trick was LOTS of free bore to keep the pressure down.

 

[IdahoSharpshooter]

JRS,

I have owned several original Sharps rifles over the past 40 years or so. Every one with a paper patch throat had deep rifling.

 

[wapiti25]

At one time years ago I was told Shilen used shallow lands.