Slugging an oddball barrel.

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Gooddaytoya!

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Hello, some may remember my hex bore long-rifle, it's a real oddball. No way to ID it, but I like it. It's not a Whitworth and is a low value rifle. It shoots patched 58 caliber rb's tolerably well. Now I want to make an accurate slug to show to a machinist about making a hex boolitt mold for it. Not that I'm trying to be a purist, this is more of a casual hobby to me. I already made a quickie slug that measures .599 across the flats. I plan on casting the new slug near the butt end of the bbl because the front is a bit irregular for the first 2 inches. My question: should I chill the barrel to maybe 32F before pouring the lead, so that when the bbl warms there is a smidge of clearance for the slug's removal? Question 2: should I lube the bbl with something special so the slug doesn't get stuck? Please don't ask me why I want to do this, I just do, plus I'd like to shoot an elongated bullet with this contraption. TY in advance, Goodaytoya!
 
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Hello, some may remember my hex bore long-rifle, it's a real oddball. No way to ID it, but I like it. It's not a Whitworth and is a low value rifle. It shoots patched 58 caliber rb's tolerably well. Now I want to make an accurate slug to show to a machinist about making a hex boolitt mold for it. Not that I'm trying to be a purist, this is more of a casual hobby to me. I already made a quickie slug that measures .599 across the flats. I plan on casting the new slug near the butt end of the bbl because the front is a bit irregular for the first 2 inches. My question: should I chill the barrel to maybe 32F before pouring the lead, so that when the bbl warms there is a smidge of clearance for the slug's removal? Question 2: should I lube the bbl with something special so the slug doesn't get stuck? Please don't ask me why I want to do this, I just do, plus I'd like to shoot an elongated bullet with this contraption. TY in advance, Goodaytoya!
Curious as to how much you are allowing for shrinkage of the lead after it has cooled? Any alloy in it will change shrink rate compared to pure lead. For a muzzleloader I prefer using an oversized lead slug pushed down a well oiled bore that is that is then slide hammered back out with a brass rod. Another option is Cerrosafe, but I believe you still need the brass rod slide hammer behind it in case it gets stuck. No practical way to push it out unless the breech plug is removed.

Best of luck on your quest.
 

Gooddaytoya!

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Curious as to how much you are allowing for shrinkage of the lead after it has cooled? Any alloy in it will change shrink rate compared to pure lead. For a muzzleloader I prefer using an oversized lead slug pushed down a well oiled bore that is that is then slide hammered back out with a brass rod. Another option is Cerrosafe, but I believe you still need the brass rod slide hammer behind it in case it gets stuck. No practical way to push it out unless the breech plug is removed.

Best of luck on your quest.
You and Phil Coffins: I do plan on removing the breech to do this. The slug will be cast about 4-5 inches above the breech end of the bbl. The breech plug is no big problem to remove and is sealed with anti size compound, so all is well "down there". Any objections to driving the slug out by placing the rod down the bbl and driving the slug backward, out the breech end? My hope is that if I'm careful, the slug won't scrape against the breech threads and be marred by them. Part 2) Pushing an oversized slug normally does work, but this bbl has a twisted hexagonal bore, which requires a whole lot more pounding, especially for an elongated slug. That's why I mentioned cooling the bbl before the pour, which seems to me would create a bit of clearance after the bbl warms. Sense or nonsense?
 

Phil Coffins

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A cool barrel will make the casting have wrinkles and voids so will be inaccurate to measure. It’s the same as casting bullets to shoot, hot mold and metal fills out and gives the form you need.
 
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You and Phil Coffins: I do plan on removing the breech to do this. The slug will be cast about 4-5 inches above the breech end of the bbl. The breech plug is no big problem to remove and is sealed with anti size compound, so all is well "down there". Any objections to driving the slug out by placing the rod down the bbl and driving the slug backward, out the breech end? My hope is that if I'm careful, the slug won't scrape against the breech threads and be marred by them. Part 2) Pushing an oversized slug normally does work, but this bbl has a twisted hexagonal bore, which requires a whole lot more pounding, especially for an elongated slug. That's why I mentioned cooling the bbl before the pour, which seems to me would create a bit of clearance after the bbl warms. Sense or nonsense?
You do realize that the cast lead slug you end up with will not be the exact size of your bore? What is your plan to account for that shrinkage?

If you are insistent on getting an exact casting of your bore, why not use Cerrosafe? The stuff is made for doing what you want, getting a chamber casting. As it cools it shrinks a bit (30 minutes), then after 60 minutes grows back to the ‘exact’ size of the chamber it was cast in. It continues to grow a bit over time, but before that occurs one can have taken all the measurements they desire.

 
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Just brain storming here. But what about hanging a long smallish bolt or piece of all thread with a nut/washer on the end down the bore. Pack some “Oakem” down around it, pour lead, cool, draw out slug. You could always put the brass rod down the barrel first too, just in case. More I think about it, two nuts on the end of the threaded rod with a slightly over bore piece of leather sandwiched between. Would not even need the Oakem.
 

M. De Land

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Hello, some may remember my hex bore long-rifle, it's a real oddball. No way to ID it, but I like it. It's not a Whitworth and is a low value rifle. It shoots patched 58 caliber rb's tolerably well. Now I want to make an accurate slug to show to a machinist about making a hex boolitt mold for it. Not that I'm trying to be a purist, this is more of a casual hobby to me. I already made a quickie slug that measures .599 across the flats. I plan on casting the new slug near the butt end of the bbl because the front is a bit irregular for the first 2 inches. My question: should I chill the barrel to maybe 32F before pouring the lead, so that when the bbl warms there is a smidge of clearance for the slug's removal? Question 2: should I lube the bbl with something special so the slug doesn't get stuck? Please don't ask me why I want to do this, I just do, plus I'd like to shoot an elongated bullet with this contraption. TY in advance, Goodaytoy
 

M. De Land

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I'd pull the breech plug and cerosafe cast the bore. It will be exactly the size of the bore where it was cast in about 45 minutes.
 
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rich pierce

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I’ve slugged dozens of barrels. If you’re going to work from the breech end and hope to drive it out the breech, first examine how a tight patch on a jag exits the breech. It’s very common for the breech plug face to mar the very end of the bore and create a little lip that will mess everything up royally when you drive the slug out the breech end.

I agree the barrel must be very hot to get a good pour with lead. Much too hot to handle.

Not sure I understand why you need an extremely accurate slug ( why a thousandth of an inch of shrinkage matters to anyone). The bore will vary more than that on an old gun.

There is a strong possibility that what you think of as a hexagonal bore is the result of a badly done freshing job during the gun’s lifetime of use. I’ve seen it before. Of course it could be hexagonal but that’s a lot of work for an ordinary rifle.
 

Gooddaytoya!

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You and Phil
You do realize that the cast lead slug you end up with will not be the exact size of your bore? What is your plan to account for that shrinkage?

If you are insistent on getting an exact casting of your bore, why not use Cerrosafe? The stuff is made for doing what you want, getting a chamber casting. As it cools it shrinks a bit (30 minutes), then after 60 minutes grows back to the ‘exact’ size of the chamber it was cast in. It continues to grow a bit over time, but before that occurs one can have taken all the measurements they desire.

Good suggestions and grist for the mind.I agree that a cold bbl will probably f-up the slug, so I'm abandoning that idea ,I'm thinking I 'need' a bullet that is slightly narrower than the bore, and that a certain amount of shrinkage might be what I need. My present question is about the theoretical diameter of the cast bullet from whatever mold I end up with.I don't remember the clearance of the conical bullets of the Whitworth rifles, but I do remember they are snug, I assume they are slightly under the bore size but how much I don't know. One or two thousandths? I want to cast hexagonal elongated bullets, that fit as hex bullets of this type should. So, for instance, if the bbl is .599 from flat to flat, I have to know what the bullet diameter should be: .590, or .589? I know this will be a heavy bullet, and I have to be careful, and I won't make it very long, not nearly the BC of the original Whitworth boolits. The secondary purpose of the slug is to replicate the twist of the bbl. Guidance, anyone, or will I be winging it in this one? To me, this is very interesting
I’ve slugged dozens of barrels. If you’re going to work from the breech end and hope to drive it out the breech, first examine how a tight patch on a jag exits the breech. It’s very common for the breech plug face to mar the very end of the bore and create a little lip that will mess everything up royally when you drive the slug out the breech end.

I agree the barrel must be very hot to get a good pour with lead. Much too hot to handle.

Not sure I understand why you need an extremely accurate slug ( why a thousandth of an inch of shrinkage matters to anyone). The bore will vary more than that on an old gun.

There is a strong possibility that what you think of as a hexagonal bore is the result of a badly done freshing job during the gun’s lifetime of use. I’ve seen it before. Of course it could be hexagonal but that’s a lot of work for an ordinary rifle.
First, many thank-yous about that common minor breech deformity! Excellent to know! SecGood thinking, but it actually is a hexagonal bore. Think this thought: The slug will be an almost exact copy of the bullets I plan to make, except the bullets will be a few thousandths narrower, as in the original actual Whitworths. It's rate of twist is 1/66 which is too slow to be some kind of legitimate attempt to make a large bore Whitworth.The bore is Very weird looking, concentric swirly looking when I peer down using a tiny light. Def not lands and grooves. This one is so odd that I think I would need to have it examined by an expert just so I could relay his opinion to you guys so you could be convinced. There is a well known muzzleloader gunsmith about 65 miles from me, maybe I should give him a look, but he's already rather ho-hum about my oddity, just to confirm what I already know. The hurried slug I did already create by the pounding-in method was a perfect hex. What I should have asked you guys at the start was, when I do create an elongated bullet, how tightly should it fit (in the Whitworth bullet fashion) or another way to ask is, how many thousandths smaller than the bore should the boolitt be? This question may be for Whitworth experts. Or I may have to figure my own way on this one. Some may ask "Why not just settle for using RBs?" Well to tell the truth I like rifles and anything that goes bang, and I think I'm on a mission.
 

rich pierce

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Sounds like a fun project. I’m not a machinist so am trying to figure out how the bullet mold will be cut. Best of luck!
 

Gooddaytoya!

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Sounds like a fun project. I’m not a machinist so am trying to figure out how the bullet mold will be cut. Best of luck!
Machining the mold will be x-PEN-sive, if I can find a machinist who wants to do it. It's a slightly twisted hexagonal bullet of all things. He might want CAD drawings, which would be too large an added expense. But I'm not there yet. Now I need to talk to some Whitworth owners. Thank you all for your input, it was def helpful and saved me a misstep.
 
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