boolit sizing for revolver help

[chevyiron420]

In the past I have been spoiled by always having my cylinder throats being .001 or .0015 over barrel groove. Now I'm working with cylinder throats of .315 and barrel .312, so I have some questions.
1, what should I size too?
2, how much over groove dia. can I go?
3, how much under cylinder throat can I go?
4, what kind of problems will I encounter in either direction?

What seems to be happening is a lead ring is building up in the forcing cone pretty quickly and then it starts smearing up the barrel. After 25 shots the barrel was leaded about a quarter inch up the bore. It wasn't to hard to clean with some chore boy, but the cone fought me hard!:-?

[44man]

Only some testing is what I would do. Try .313" to 314" and see.
It could be your lead is too soft and is skidding or slumping, trying to fill the cone.

[badgeredd]

I have a Colt 38 S&W that has the same problem. Upon advice from several older members, I sized the boolits to fit the cylinder. My boolits are sized.360 and the bore is .356. I use 75% pure and 25% COWW lead for an alloy, air cooled. My loads are a little below full speed. I haven't had any trouble with leading or pressure. I suggest you do as 44man suggested, but I'd likely jump right to .314 to see how that worked.

Edd

[cbrick]

Size to a mild snug fit in the throats. If it takes more than tapping with a pencil to push them through they are too tight. If they fall through they are too loose.

Next question is, does your mold cast that large? If so size to a mild snug fit and go shoot some and see if the leading stops. If not lube without sizing and go shoot some.

Rick

[44man]

Rick is right, some molds are grossly undersize.

[chevyiron420]

Only some testing is what I would do. Try .313" to 314" and see.
It could be your lead is too soft and is skidding or slumping, trying to fill the cone.
Thanks 44man, I defenetly have some testing to do! I have been sizing .314, its the biggest die I have. I have tryed WDWW alloy and accedently #2 alloy and I think the #2 was worse.

[chevyiron420]

I have a Colt 38 S&W that has the same problem. Upon advice from several older members, I sized the boolits to fit the cylinder. My boolits are sized.360 and the bore is .356. I use 75% pure and 25% COWW lead for an alloy, air cooled. My loads are a little below full speed. I haven't had any trouble with leading or pressure. I suggest you do as 44man suggested, but I'd likely jump right to .314 to see how that worked.

Edd
Thanks Edd, I have had the exact same experience with my regulation police smith in 38S&W. I didnt want to cast boolits just for these guns, but I may have to. I have been sick and I'm avoiding the casting pot. A softer boolit may be in order.

[chevyiron420]

Size to a mild snug fit in the throats. If it takes more than tapping with a pencil to push them through they are too tight. If they fall through they are too loose.

Next question is, does your mold cast that large? If so size to a mild snug fit and go shoot some and see if the leading stops. If not lube without sizing and go shoot some.

Rick

Thanks Rick, I wanted to go over today and see how the unsized boolits fit but I'm not feeling to good. I think the 100 grain mold is big enough but .314 is the biggest die I have and boolits sized with that die fall through. What do you think about tumble lubing the boolits as cast?