Paper patch groove depth vs bullet weight

[Steveoko922]

What is the typical groove depth seen on conical paper patch barrels and what are the limitations on the bullets ability to obturate the bore?

I have a .408 land, .427 groove rifle that shoots 289 grain bullets. I'm having trouble locating a hollow base bullet but a flat base is avaliable.

I'm worried the soft lead bullet won't be heavy enough to slug up and fill the rifling.

 

[paulab]

What is the typical groove depth seen on conical paper patch barrels and what are the limitations on the bullets ability to obturate the bore?

I have a .408 land, .427 groove rifle that shoots 289 grain bullets. I'm having trouble locating a hollow base bullet but a flat base is avaliable.

I'm worried the soft lead bullet won't be heavy enough to slug up and fill the rifling.

Soft lead will easily bump up to groove diameter. Why do you think you need a hollow base bullet? A 20:1, 24:1, 30:1 or pure lead flat base bullet will easily bump up to groove diameter. What is your twist rate. That will determine how big of a bullet your rifle will stabilize.

 

[Phil Coffins]

Sharps rifles that used paper patch bullets had .001” - .0015” depth of rifling and when a paper patch bullet was used they were smaller than bore size to insure loading ease. Dr. Mann’s book documents that metal jacketed bullets obturated. A pure lead bullet is as heavy as you can get, adding alloy makes a lighter slug.