Question on mould

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GoodRabbitPilgrim

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Hi,

I'm looking to order a mould for the 20G smoothie for round ball. From what I've read here a .600 ball with a .010 patch being slightly under bore of a .620 bore would be a good place to start.

I can't get anything out of the states at the moment with the usps suspension of shipping here so am looking elsewhere. This British company makes them but on their website they have this formula for their mould size. I mentioned to the guy that I was thinking of a .600 ball with a 0.010 patch ans he gave me an equation that worked to a 0.594 mould. I'm not doubting him I just don't get the logic. Does this make sense to you guys?

Screenshot_20211015-222904_DuckDuckGo.jpg
 

Notchy Bob

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Gosh, who knew it was that complicated?

I don't do a lot of shooting with patched round balls (PRBs) in my smoothbores, but I have found that a .600" patched ball can be pretty tight, especially with some fouling. I also found that balls cast from scrounged range lead, mostly fired by cowboy action shooters, drop out of my .600" Lee mould at about .603". Harder alloys make larger balls than pure lead, using the same mould. The formula shown actually accounts for that.

Anyway, the balls I like best for my 20 gauge smoothbores are pure lead in the .595" size. Note that a true 20 gauge is .615". Using a harder alloy (e.g. scrounged range lead), these balls would probably go about .597" or .598" from the same mould. Lead shrinks a little as it cools. Harder alloys shrink a little less. So, mould cavities are cut very slightly oversized.

I think the mould-maker is confusing bore size and ball size in his "Patches" paragraph. You already know what ball size you want. It looks as if you multiply the desired ball size by 1.007 for pure lead or 1.005 for hard alloys to get the ball you want. I think most commercial mould makers do that calculation for you, and recommend a most appropriate alloy. The subject mould-maker wants you to do the calculation for yourself, and he'll cut the mould cavity to the size you tell him.

We'll see what others have to say. Good luck!

Notchy Bob
 

Brokennock

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One of my two 20 gauge smoothbores likes loose loads. A .600 ball with .010 patch,,,, that shoots well in the other gun,,,, doesn't perform well at all.
But, a .595 ball with the same patch shoots really well.

Is there any way you can get your hands on some roundball of different sizes and a few samples of patch material of different thicknesses to try before you commit to a mold?

Just a thought, but, Probably easier to deal with a slightly undersized ball and thicker patches than a too large ball and not be able to get patches thin enough. Of course,,,, then,,,, the gun that likes the patched .595 ball also shoots even better with a .610 ball sandwiched between wads and cards.
 

GoodRabbitPilgrim

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One of my two 20 gauge smoothbores likes loose loads. A .600 ball with .010 patch,,,, that shoots well in the other gun,,,, doesn't perform well at all.
But, a .595 ball with the same patch shoots really well.

Is there any way you can get your hands on some roundball of different sizes and a few samples of patch material of different thicknesses to try before you commit to a mold?

Just a thought, but, Probably easier to deal with a slightly undersized ball and thicker patches than a too large ball and not be able to get patches thin enough. Of course,,,, then,,,, the gun that likes the patched .595 ball also shoots even better with a .610 ball sandwiched between wads and cards.
The whole problem is I can't find anyone with a ball to fit my bore to try. So I'm relying on getting something imported. I was happy to just get a Callahan bag mould at .600 and cast from there.

Based on cost I'm probably not going to get a .595, .600 and .610 mould. I'm just trying to figure out what the safest bet would be. Sounds like maybe the .595 with varying thickness of patches?
 

Brokennock

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The whole problem is I can't find anyone with a ball to fit my bore to try. So I'm relying on getting something imported. I was happy to just get a Callahan bag mould at .600 and cast from there.

Based on cost I'm probably not going to get a .595, .600 and .610 mould. I'm just trying to figure out what the safest bet would be. Sounds like maybe the .595 with varying thickness of patches?
So, you have the Callahan .600 mold?
If so, if you are getting another mold, I'd get the .595 mold.
 

Steve Martin

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Just get a mold and then you can "play" with different patch thickness. Much easier to try different patches than different molds. My 20 gauge/.62 caliber smoothbore likes .600 balls with a rather thick .18 patch. You can get a mold for .595 if you are worried .600 might be too tight for your gun but you are gonna have to just pick whatever mold you can most easily get It sounds like and try patches from there.
 

SDSmlf

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I'm looking to order a mould for the 20G smoothie for round ball. From what I've read here a .600 ball with a .010 patch being slightly under bore of a .620 bore would be a good place to start.
Couple of questions for you. Have you measured the actual bore diameter? Do you know if the gun has any type of choke? What make is the gun?

I use a Lee .600” diameter mold for my 62 caliber rifled barreled guns and a couple of 20 gauge guns that I had. Never though much about it, just figured out what patch thickness worked with each gun without much difficulty. Without knowing the bore size of your particular gun, I would error on the side of caution and go with a .594”/.595” mold as other have suggested and then find a patch thickness that works. As long as your 20 gauge is not at the low end of normal manufacturing tolerances and significantly undersized you should be good to go.
 

GoodRabbitPilgrim

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I spoke with Pedersoli and interestingly they suggested the best load they've seen for the Indian trade gun is 60 grains of 2F a .614 ball and a 0.010 patch. Sounds like a tight combination.

They said a maximum powder charge of 80 grains 2F which surprises me. I would have thought it could go higher (not that you would need to).
 

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