Round Ball Tumbling With Graphite

Jim in San Diego said:

I’ll have to try the graphite! I have a rock tumbler and successfully tumbled a bunch of 50 cal round balls, but then a batch came out severely oxidized.

I didn’t do anything different, but they were very much like your lower picture.

Then I tried to tumble larger round balls for a 75 caliber blunderbuss I’m having made. Many of the balls came out egg shaped.

Did I tumble too long? Or is tumbling not effective on the larger round balls?

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If you have egg shaped balls, you were dropping them before they cooled enough. Drop them into a bucket of water.

Pro Libertate said:

The patch doesn’t stay with the ball the whole length of the barrel during firing, so I should think there’s plenty of opportunity for the ball’s lubricity to affect velocity.

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Seriously??

This all seems like a waste of time and energy. Unless someone says here is my one hole group at 75 yds after and my 3" group before I don't see the point.

NotDanielBoone said:

This all seems like a waste of time and energy. Unless someone says here is my one hole group at 75 yds after and my 3" group before I don't see the point.

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You simply place your round balls into a tumbler with a single squirt of graphite for an hour or two. Hardly a huge outlay in terms of time or energy. I fail to see how smoother, more uniform round balls could be a bad thing.

Jim in San Diego said:

Then I tried to tumble larger round balls for a 75 caliber blunderbuss I’m having made. Many of the balls came out egg shaped.

Did I tumble too long? Or is tumbling not effective on the larger round balls?

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Thats interesting! Just how long did you tumble them? I tumbled my .735 caliber balls overnight for approximately six/seven hours and I didn’t experience any malformation— they came out perfectly round.

Regarding the oxidation on the other balls… is your tumbler clean? Could there be any residue from polishes or other chemical products used during past tumbling projects? I’ve not run into this issue, so I can only theorize.

waksupi said:

What your picture shows me, is your lead wasn't hot enough when you were pouring according to the wrinkles that show, and there may have been a flake of lead on the mold faces, leaving a mold line.

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My molten lead read a virtually constant temperature of 775 degrees, and I ensured my mold faces were clean. The only thing I can think of is that the orifice on my bottom pourer was getting clogged and that lead wasn’t filling the mold as quickly as it should have.

You’ve got two mold halves coming together (it’s not seamless), so I fail to see how a mold line is avoidable.

Pro Libertate said:

My molten lead read a virtually constant temperature of 775 degrees, and I ensured my mold faces were clean. The only thing I can think of is that the orifice on my bottom pourer was getting clogged and that lead wasn’t filling the mold as quickly as it should have.

You’ve got two mold halves coming together (it’s not seamless), so I fail to see how a mold line is avoidable.

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Well, I have at least 50 molds, none show a seam.

waksupi said:

Well, I have at least 50 molds, none show a seam.

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Huh! Are any of those molds .70+ caliber? Perhaps the seams are more prominent as you get into larger calibers. Then again, maybe it’s due to some other factor(s). I plan on doing some experimentation this weekend and have considered using a cast iron smelting pot and dipper as opposed to my Lyman bottom pour furnace.

I did cast some .36 cal round balls in addition to the .735 and those turned out as perfect as could be. Of course, the bigger the ball, the more obvious imperfections become, and I’d imagine that all the different variables that come into play during casting (lead/mold temperature, rate of pour, etc.) become more critical.

Pointless. Value of this procedure is on the targets. A test will show no difference between tumbled and not tumbled.

Rifleman1776 said:

Pointless. Value of this procedure is on the targets. A test will show no difference between tumbled and not tumbled.

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Several members have already chimed in and claimed otherwise— that they have witnessed an increase in accuracy after tumbling their balls. It only stands to reason that the more uniform and free of irregularities a ball is, the more accurate it will be.

Now, I make no claims regarding the inclusion of graphite other than that they do appear smoother between my fingertips than those that have been tumbled without it— and significantly more so than those that haven’t been tumbled at all. This might improve velocity and ease of loading in a smoothbore. I have neither the time nor energy to commit to exhaustive testing, so I’ll leave that to someone else.

With all due respect, there’s a lot of contradictory statements here; however, those that dismiss tumbling as “pointless” or “silly” apparently make those assertions without having ever tried it for themselves. Those that do tumble swear by it and tout sometimes pretty significant accuracy gains.

Pro Libertate said:

The patch doesn’t stay with the ball the whole length of the barrel during firing ...

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I believe you are mistaken, as the pressure/force behind the patch is what is pushing the ball forward and out the muzzle. In physics it would be impossible for the ball to move faster than the force behind it pushing it forward.

These high speed camera photos show a patched ball in flight and only after leaving the muzzle does the patch deaccelerate away (lag behind) the ball due to drag, drag being but 1 of the 6 factors of External Ballistics.

I concede that I was mistaken. Thanks for the photos— I couldn’t find photographic evidence of this via Google search to save my life! I must’ve spent a couple hours looking for photos/videos of the patch and ball leaving the muzzle.

Pro Libertate said:

Huh! Are any of those molds .70+ caliber? Perhaps the seams are more prominent as you get into larger calibers. Then again, maybe it’s due to some other factor(s). I plan on doing some experimentation this weekend and have considered using a cast iron smelting pot and dipper as opposed to my Lyman bottom pour furnace.

I did cast some .36 cal round balls in addition to the .735 and those turned out as perfect as could be. Of course, the bigger the ball, the more obvious imperfections become, and I’d imagine that all the different variables that come into play during casting (lead/mold temperature, rate of pour, etc.) become more critical.

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Largest I pour is .600.

Parting lines can sometimes be eliminated by a firmer squeeze of the handles and, of course, keeping the mold faces clean.

waksupi said:

Largest I pour is .600.

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I see. This mold is a Lyman, whereas my others are Lee. A cursory internet search seems to indicate that Lyman molds are notorious for visible casting seams. I don’t know if there’s any truth behind this or not, but there is a seam visible in the product photos for the .735 cal mold (shown below). Then again, if one tumbles this is a non-issue and any seam will altogether disappear.

longcruise said:

Parting lines can sometimes be eliminated by a firmer squeeze of the handles and, of course, keeping the mold faces clean.

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I’ll give that a try, thanks! I didn’t appear to have any build-up on the mold faces, but I’ll check their alignment and will apply more pressure to the handles next time around.

Also check for debris or dirt/rust in the line up pin holes, I once found cleaning them out helped eliminate the mold seam.

bpd303 said:

Also check for debris or dirt/rust in the line up pin holes, I once found cleaning them out helped eliminate the mold seam.

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Thanks for the tip. I don’t believe that to be the case here, as the mold is brand new and I scrutinized it pretty well before use, but I’ll keep that in mind. I spray my molds down liberally with Ballistol before putting them away and wipe off any excess before I start casting.

Pro Libertate said:

I see. This mold is a Lyman, whereas my others are Lee. A cursory internet search seems to indicate that Lyman molds are notorious for visible casting seams. I don’t know if there’s any truth behind this or not, but there is a seam visible in the product photos for the .735 cal mold (shown below). Then again, if one tumbles this is a non-issue and any seam will altogether disappear.

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I saw them on the pictures of your tumbled balls.

I don't know for sure since they never wrote about it but my ancestors must have had a special box with some graphite in it to perfect their cast balls in the back of their wagon when they bounced their way over the Oregon trail in 1845. Otherwise, them Indians would have got 'em.