Figuring out the perfect conical size.

D

Detonator

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Hi I'm new here.

I have to start with a question. Several years ago I bought a custom-made longun. It's a 60 caliber bore. The exact measurements are: .625 and .594 X 36 inches, made with my mechanical micrometer.

.580 balls work with the right patch.

Somebody told me that conicals and minis would need to be a "perfect fit".

Now I have to find out what diameter conical bullets should be for this barrel. I'll no doubt need a custom mold. I'm interested in flat-bottomed conicals at about 600 grains. Is that the same diameter as a mini would need? Since I know next to nothing about BP hardware, I can't even guess at the answers.

Det
 
Your long gun barrel seems to have deep rifling grooves.
A custom sizing die can be used to size a wide variety of bullets. And the outfit below can enlarge the size of a die if the diameter proves to be too small. That way the mold doesn't need to be the perfect size.
Lee makes custom sizing dies but has temporarily suspended most custom work because their business is booming.
But there's other outfits that will make them including this one:

http://www.doughtyent.com/Pages/SizingDies.html

A custom mold can also be enlarged to some degree.

http://www.hollowpointmold.com/
 
Last edited:
A minie needs to be .002 under bore size. A flat based conical needs to be bore size with a little taper to help it get started. Your rifling twist rate will determine how well it shots round balls and conicals.
 
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