12 Gauge Slug Mould

[mattsheik]

I am in the process of getting a mould made up for a 12 gauge slug gun.  My question is, normally I've always heard to size it .001" larger than the bore?  Is this the same for a rifle?  Even a rifle that will be firing a heat treated bullet?  I've also heard that a hard bullet will lead the forcing cone area if it's too hard and not driven fast enough?  Does anyone have some experience or ideas to share on this subject?  I do not want to have to cut multiple moulds!  Big moulds are expensive!!! 

Thanks to all,

Matt

[Cat Whisperer]

The .001 (or so) oversize is so the bullet will engage the rifling.  On a shotgun you NEED clearance.

Can't comment on how much.  I have my first mould blocks for 10ga cut now.

One will be for the cylinder bore, another for using inside a standard shotcup.

At the end of the summer I'll know which works best.

Then I'll work on my 20ga fully-rifled one.  That will be designed to engage the rifling.

[mattsheik]

I realize that that is why it is oversize now, after reading your post.  That makes sense.  So on a rifled slug gun you would also want the slug .001 oversize correct??  Then concerning hardness, I've read dixie slugs are bhn of 30.  So very, very hard.  But, there's are sized to the bore of a hastings barrel, not oversize?  But like I mentioned super hard?  Maybe that is the way to go? 

Thanks