How to figure ball diameter for your guns bore

[M. De Land]

Here is the page out of the hard cover addition of Roberts Book Ed.
I made a Cerosafe cast of my match barrels bore and the groove diameter mics .478. The Bore is .451 so each groove is .0135 deep for a total cross groove depth of .027. If I take my .445 ball and add full patch thickness on both sides of the ball in relation to the groove (.018 x 2 = .036). Ball at .445+ both sides of patch .036 I get to .481 and my groove diameter mic's .478.
Ball plus double patch thickness gets me to .481 using the groove diameter as the base measurement I get within .003 of a match so with a .003 patch compression into the ball the grooves are sealed and the ball fully engraved. I know the ball is patch engraved with this component combination because I have pulled some I dry balled and checked.
So the re- calibrated formula for ball diameter seems to work out using groove diameter minus double patch thickness and figuring .003 of patch engrave-meant into the ball. This is a snug fitting load that does not need to be pounded down but probaly 20-25 lbs of pressure using a solid steel 5/16s range rod with a down the muzzle bore protector and delivers accuracy with good patch performance.
I think that makes sense................ no ?
Note the crown and how sharp the land ends are after hundreds of rounds shot. This is because a down bore brass muzzle guide/protector is always used when loading or cleaning.
The polish ring on top is from patch knife rub.

I was thinking that this is a good example of the practice of so called "reverse engineering" , a ten dollar phrase for(backing into a remedy)!

 

[M. De Land]

I was thinking that this is a good example of the practice of so called "reverse engineering" , a ten dollar phrase for(backing into a remedy)!

I need to apply this idea to the rest of my muzzle loaders and see if it holds true or is it just a fluke on this one. Interesting exercise though.

 

[Jim in Wisconsin]

That's interesting that your book says "plus". I don't know how to take pictures and get them on here, but my page looks just like yours except says "minus". My book is an old hard back "Muzzle Loading Cap Lock Rifles" by Ned H. Roberts with a last copywrite date of MCMLII (1952).
Looks like we found a printing error of some sort, old Ned would be ticked off I suppose! It is a good book to have and has some nice pictures.

In general, I think if the ball with a greased patch can be pushed in with finger, it's probably too loose and if you have to pound hard to get it to start that's too tight. Patch material isn't always real consistent in thickness or strength - amount of lube, ball diameter and hardness might vary, maybe it doesn't pay to try to be real precise about this.

 

[Grenadier1758]

I was thinking that this is a good example of the practice of so called "reverse engineering" , a ten dollar phrase for(backing into a remedy)!

What I am seeing of your procedure is what could be thought of as "Total Quality Management". It is a procedure to determine the best method to obtain the desired results. It begins by measurement. It starts with your Cerosafe casting of your bore to get the exact measurements. Then you record your measurements to get the land-to-land bore measurement and the groove diameter. From that information the groove depth is obtained. From previous best practices we know that we have to strive to have the patch material compress to the groove depth and the windge between the ball and the lands. With a soft lead ball, we have the patch material engrave as the patch material is compressed between the ball and the lead. Now we can select a ball size. Knowledge of previous best practices would indicate a windage of 0.005" or less to compress the patch material. Therefore we take a starting ball diameter of twice the windage less than the land-to-land diameter. Is there a commercial ball or cast ball that meets that dimension? We can choose a larger ball diameter for a tighter fit or a smaller ball diameter for an easier fit. Now we choose a suitable patch material that at its compressed measurement is close to the groove depth plus the windage. In most cases that will be the groove depth (in this case 0.0135" plus 0.005". So, our 0.018" cotton drill cloth will be close. It will compress on the lands and as it fits into the grooves it will lightly compress from the groove. I'm not giving specific instructions for a particular barrel, ball, and patch as I did that earlier, but this procedure can be applied to your other rifles. Once we have a starting configuration, it's time to test to see if our results meet our requirements.

n all cases this is a determination of a possible starting configuration that can be adjusted to obtain ease of loading, on target accuracy, or acceptable hunting performance.

My method is just a guideline to get started, the findings are not absolutes.

It's all part of this traditional muzzleloading journey

 

[Snydly]

Just remember... if you are using .018 patch material,,,, it is doubles as it is basically on two sides. Thus it is actually .036. That sound about right?

 

[Grenadier1758]

Yes, one has to consider twice the patch thickness as well as twice the groove depth.

 

[M. De Land]

What I am seeing of your procedure is what could be thought of as "Total Quality Management". It is a procedure to determine the best method to obtain the desired results. It begins by measurement. It starts with your Cerosafe casting of your bore to get the exact measurements. Then you record your measurements to get the land-to-land bore measurement and the groove diameter. From that information the groove depth is obtained. From previous best practices we know that we have to strive to have the patch material compress to the groove depth and the windge between the ball and the lands. With a soft lead ball, we have the patch material engrave as the patch material is compressed between the ball and the lead. Now we can select a ball size. Knowledge of previous best practices would indicate a windage of 0.005" or less to compress the patch material. Therefore we take a starting ball diameter of twice the windage less than the land-to-land diameter. Is there a commercial ball or cast ball that meets that dimension? We can choose a larger ball diameter for a tighter fit or a smaller ball diameter for an easier fit. Now we choose a suitable patch material that at its compressed measurement is close to the groove depth plus the windage. In most cases that will be the groove depth (in this case 0.0135" plus 0.005". So, our 0.018" cotton drill cloth will be close. It will compress on the lands and as it fits into the grooves it will lightly compress from the groove. I'm not giving specific instructions for a particular barrel, ball, and patch as I did that earlier, but this procedure can be applied to your other rifles. Once we have a starting configuration, it's time to test to see if our results meet our requirements.

n all cases this is a determination of a possible starting configuration that can be adjusted to obtain ease of loading, on target accuracy, or acceptable hunting performance.

My method is just a guideline to get started, the findings are not absolutes.

It's all part of this traditional muzzleloading journey

I like formulas that can predict repeatable results rather than chasing ones tail in the dark. I have also experimented with .440 ball diameters and found they are easier to load but not quite up to the same accuracy level as a .445 ball. I have molds for each.
Another surprise for me in this exercise was compressing my lubed shirt felt patch material between the jaws of my 1 inch mic quite firmly and only getting .001 compression. I would have expected about .005 or so but it was much more firm than I had thought it would be. The shirt felt I like to use is very tight weaved and 100 percent cotton.
The lube I have settled on is winter grade windshield wash who's ingredients are water, alcohol and liquid soap.
This lube works very well in hot or cold conditions to keep bore fouling to a minimum for a ten shot relay string before a more complete job of wiping out for the next relay.

 

[M. De Land]

Just remember... if you are using .018 patch material,,,, it is doubles as it is basically on two sides. Thus it is actually .036. That sound about right?

Yes, that is in the adjusted calculation given. Makes me wonder what else is mis-printed in this edition of Ned's book!

 

[M. De Land]

I like formulas that can predict repeatable results rather than chasing ones tail in the dark. I have also experimented with .440 ball diameters and found they are easier to load but not quite up to the same accuracy level as a .445 ball. I have molds for each.
Another surprise for me in this exercise was compressing my lubed shirt felt patch material between the jaws of my 1 inch mic quite firmly and only getting .001 compression. I would have expected about .005 or so but it was much more firm than I had thought it would be. The shirt felt I like to use is very tight weaved and 100 percent cotton.
The lube I have settled on is winter grade windshield wash who's ingredients are water, alcohol and liquid soap.
This lube works very well in hot or cold conditions to keep bore fouling to a minimum for a ten shot relay string before a more complete job of wiping out for the next relay.

I should point out that this combination is the best I have yet to discover for match work. The patches are soaksd in the windshield was fluid and then squeezed between the fingers leaving them only damp for both patching and wiping.
For a hunting load (I have never tested yet) I'd try a milk carton over powder wad and saturated bear oiled ball patch squeezed out. This would prevent corrosion, seal the charge against moisture and oil migration into the powder charge.

 

[Urban Coyote]

I must be doing it all wrong. I test patch and ball combinations until I find one that fits my needs. Needs? Yup, if I'm shooting targets in competition I might want a tight fit and it might require some effort to load. If I'm fixing to go hunting I might want the most accurate load that allows me to fire a few, say 5 shots, without wiping the bore yet allows for ease of loading, reasonably.

 

[Urban Coyote]

Played with patch material today. T/C PA Hunter Carbine, I love this gun. Anyway, end result using .490 ball, spit lubed red stripe ticking patch .017, and 70 grains of Schuetzen 3F. I fired several five shot strings using various patch material, all cotton. I started a 5 shot string using a .495 ball and .010 patch but after three shots it was obvious that was not going to work for me.

Here is where I ended up at 50 yards. I'd fired three shots when some over anxious shooter who'd just walked onto the range called for a target check. Afterwards I fired the two shots low and to the right.

 

[Marplot]

So the .018 patch would equate to .036?

 

[Grenadier1758]

Yes, there is 0.036" of an inch of patching to account for along with the ball.

However, @Marplot, it's not as simple as doubling up the patch thickness to determine the effect of the ball, lands and groove. Patch material compresses into the grooves. That compression between the lands and the ball will engrave into the ball. Then the bunching up of the patch as it gathers around the ball are also factors.

In most cases, there is a gap of 0.005" between the ball and the land. That 0.018" thick patch has to be compressed to fit in there. Normal patch compression will work for that. In new barrels, the sharp corners of the lands cut into the patch to force the fit. When the corners of the lands become smooth and slightly rounded to prevent cutting of the patch and with a soft lead ball the patch material will engrave on the ball for the last few thousandths of an inch to load the ball. The rest of the patch bunches up to slightly compress into the grooves. That's one reason why the grooves should be wider than the lands. Th wider grooves will hold more fouling and the damp and slightly compressed patch material in the grooves will better seal the bore on firing.

 

[Marplot]

Yes, there is 0.036" of an inch of patching to account for along with the ball.

However, @Marplot, it's not as simple as doubling up the patch thickness to determine the effect of the ball, lands and groove. Patch material compresses into the grooves. That compression between the lands and the ball will engrave into the ball. Then the bunching up of the patch as it gathers around the ball are also factors.

In most cases, there is a gap of 0.005" between the ball and the land. That 0.018" thick patch has to be compressed to fit in there. Normal patch compression will work for that. In new barrels, the sharp corners of the lands cut into the patch to force the fit. When the corners of the lands become smooth and slightly rounded to prevent cutting of the patch and with a soft lead ball the patch material will engrave on the ball for the last few thousandths of an inch to load the ball. The rest of the patch bunches up to slightly compress into the grooves. That's one reason why the grooves should be wider than the lands. Th wider grooves will hold more fouling and the damp and slightly compressed patch material in the grooves will better seal the bore on firing.

It seems I have blow-by with nasty residue. Patch not cut, but a hole through it. We also took a long piece of patch about .019, pushed the ball down in the muzzle until level and pulled like hell to get it out. No cuts. Two people to hold the rifle and two to pull the cloth.

BTW the rifle was made about 1858 and there was not really exact calibers. As I understand that they made a rifle and gave you a mold that would make a ball for your particularly gun. Obviously I don't have the mold!

It seems like the ball starter take more than usual effort, but the ramrod kicks in and it moves more easily after about 6 inches from the muzzle..

So here is what my micrometer says.
Ball .530
Groove to groove .564
Land to land .530

It is also a German Jaeger that may have deep refiling. I am guess that my ball is too small.

 

[Rob M.]

You are overthinking this (non) issue. Unless you are working with an old original with a strange bore size you won't have much looking to do to find the right ball size. You mentioned .50 cal. With today's modern barrels a .490" or .495" ball and proper patch will work perfectly. To find yer ball/patch combo all you need to do is try both sizes and several different patch materials. That ain't so bad as the name of the game is shooting and it requires shooting to dial in yer new smokepole.

Well said .... Just get a couple sizes of ball , anything under the bore size , won't be that many , and then try a couple different thicknesses of patching material . It ain't difficult and can be a lot of fun ... in my experience pillow ticking is always nice and usually the thickest , and I always have cotton T-shirt material laying around , usually the thinnest ...try them all and see what your rifle or gun likes .

 

[Uncle Miltie]

Circa 1860's- 1880's when Brockway was active bullets were often called balls, a hold over from the round ball days. The target rifles he made would have used picket or sugar loaf bullets, as pictured above. Later parallel sided bullets used a two piece construction with a hard lead nose and soft lead base. I wonder if the patch referred to was a paper patch?

The picket rifle was pretty much washed up when folks began using slug rifles in the early 1860's.
Mr. Brockway made many slug rifles which used a bullet more than 1 1/2 calibers in length and an oiled paper patch.