Slugging a barrel

[Jimbo Jones]

Hi, can anyone please explain to me step by step how to slug a barrel to determine the size of cast bullet required?

Many thanks, Jimbo

[lightning22]

Here’s how I did it.

Fill and old case up to the base of the neck with molten lead. When cooled I inserted a long soft lead bullet and chambered it with the rifle pointing upwards.

Then taking a long brass rod I inserted it from the muzzle end until it contacted the soft lead bullet and then pounded on the rod until it didn’t seem to want to go any further.

Ejecting the case leaves the slug behind so you just tap it out with the rod.

That should give you a pretty accurate measurement of the throat which is what you should be sizing your cast bullets to.

[Jimbo Jones]

That’s great, many thanks for your advice with this. It seems dead simple when you know!

[lightning22]

No worries, I think that method was described as pound casting on the Cast Boolits forum. It certainly worked for me, there was more effort put into making a Lee sizer work to the right diameter. My .303 is running a .314 throat from memory.

[steve R]

i had major problems with tumbling bullets in my .44 taurus ,these good chaps on here showed me how to slug which in fact solved the problem, barrell was oversized needing only .432 bullets instead of .429, ordered from the awesome shellhouse bullet company......still shooting good ,well as good as i can