How to figure ball diameter for your guns bore

[M. De Land]

I am just finishing Ned Roberts book on the cap lock muzzle loader and in the last chapter Norman Brockway gives his formula for figuring ball diameter for any muzzle loader. His formula is bore diameter plus one thickness of the patch material to be used. For example if your bore measures .400 and the patch thickness is .009 then your ball size should be .409 for that thickness of cloth patch. Bore diameter means diameter on top the lands as opposed to groove diameter.
Norman Brockway was one of the master rifle makers of the late muzzle loading era.

 

[Bad Karma]

I am just finishing Ned Roberts book on the cap lock muzzle loader and in the last chapter Norman Brockway gives his formula for figuring ball diameter for any muzzle loader. His formula is bore diameter plus one thickness of the patch material to be used. For example if your bore measures .400 and the patch thickness is .009 then your ball size should be .409 for that thickness of cloth patch. Bore diameter means diameter on top the lands as opposed to groove diameter.
Norman Brockway was one of the master rifle makers of the late muzzle loading era.

It’s been a while since I’ve read the book and I’m packing up most of them so I don’t believe I can find it easily. Does he tell us how big the hammer should be?

 

[rafterob]

That may work but would be a tight load. A lot of the latter part of that book is talking about target rifles which had become in vogue in the latter 1800's. It also discusses false muzzles and paper patched bullets. Many of us use a slightly looser combination to facilitate loading.

 

[Ed C.]

I apologize for my ignorance, but this makes no sense to me. Assuming that most .50 cal bores are .498 to .503 land to land in diameter and you use .010" patch, according to Ned Roberts you need a .508 to a .513 ball? I've got to be misunderstanding something here. I could see that being used if we were talking grove to grove diameter.

 

[Bad Karma]

I apologize for my ignorance, but this makes no sense to me. Assuming that most .50 cal bores are .498 to .503 land to land in diameter and you use .010" patch, according to Ned Roberts you need a .508 to a .513 ball? I've got to be misunderstanding something here. I could see that being used if we were talking grove to grove diameter.

Or subtracting .010 from the bore size.

 

[Grenadier1758]

Brockway is describing the target shooting practice of the early 1900's. That method of target shooting required a very tight fitting ball and patch. The patch needed to be hard driven into the soft lead ball, so the oversized ball was required. The short starter had a tip curved to match the diameter of the ball to prevent distortion of the ball surface when driven in by the loading mallet.

Most of us aren't looking for that degree of target accuracy and find an easier loading ball and patch preferable to pounding a load down the barrel. An acceptable alternative starting combination is a ball that is 0.010" less than the land to land diameter wrapped in a patch that compresses to the depth of the groove. This is fairly tight and use of a short starter is common. The patch will engrave on the soft lead ball and once started can be easily rammed to the breech.

 

[M. De Land]

It’s been a while since I’ve read the book and I’m packing up most of them so I don’t believe I can find it easily. Does he tell us how big the hammer should be?

I haven't seen anything about hammer size yet.

 

[M. De Land]

That may work but would be a tight load. A lot of the latter part of that book is talking about target rifles which had become in vogue in the latter 1800's. It also discusses false muzzles and paper patched bullets. Many of us use a slightly looser combination to facilitate loading.

Yes this was all top accuracy for target work !

 

[M. De Land]

I apologize for my ignorance, but this makes no sense to me. Assuming that most .50 cal bores are .498 to .503 land to land in diameter and you use .010" patch, according to Ned Roberts you need a .508 to a .513 ball? I've got to be misunderstanding something here. I could see that being used if we were talking grove to grove diameter.

Keep in mind most of these target rifles were using false muzzles as well for loading ball or bullet. I thought it interesting information and something to experiment with. I use a short starter for all my target shooting. I am going to measure my bores and patch material and see how close I am to his recommendation and how it works.

 

[M. De Land]

I apologize for my ignorance, but this makes no sense to me. Assuming that most .50 cal bores are .498 to .503 land to land in diameter and you use .010" patch, according to Ned Roberts you need a .508 to a .513 ball? I've got to be misunderstanding something here. I could see that being used if we were talking grove to grove diameter.

I do believe though after many years of trial that the patch material should always be made of pure cotton and have a tight weave. The cloth should be thick and tough enough to engrave the ball in the groove as well as land and be able to be loaded with no tear or cut in it from the muzzle . A good and accurate patch will usually fray the perimeter but should be able to be used again if one chose to.

 

[Rifleman1776]

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.

 

[Ed C.]

Brockway is describing the target shooting practice of the early 1900's. That method of target shooting required a very tight fitting ball and patch. The patch needed to be hard driven into the soft lead ball, so the oversized ball was required. The short starter had a tip curved to match the diameter of the ball to prevent distortion of the ball surface when driven in by the loading mallet.

Most of us aren't looking for that degree of target accuracy and find an easier loading ball and patch preferable to pounding a load down the barrel. An acceptable alternative starting combination is a ball that is 0.010" less than the land to land diameter wrapped in a patch that compresses to the depth of the groove. This is fairly tight and use of a short starter is common. The patch will engrave on the soft lead ball and once started can be easily rammed to the breech.

Ok, thanks. So we are talking about using a ball larger in diameter than the bore. Does anybody do that with todays rifles? Sounds like you'd have to custom make your own balls

 

[longcruise]

It's been a long time since I read the book so this post probably has some misunderstandings in it.

My memory suggests that the competitions of the time were shot with bullets rather than balls. Maybe they were called picket bullets apparently the widest point point of the bullet was the base and the were shot with a patch.

They had to be loaded with a false Muzzle and it had to be done perfectly. Based on the results possible with these they must be capable of exceptional accuracy but I think that any minor deviation loading would be inaccurate.

Regarding measuring the patch, the very tight fit was probably not too difficult to load with his formula given the small surface being compressed.

 

[Jim in Wisconsin]

I have that book too, and found that part. It says "The round ball as it drops from the mould should be the bore diameter minus one thickness of the patch material".
That would work good, and not be overly tight I think.

 

[rmark]

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?

 

[rmark]

One of the great defects of being at work is not having your reference library at hand

 

[Bad Karma]

One of the great defects of being at work is not having your reference library at hand

I just retired but I’ve been packing up my library so it’s not immediately to hand either…

 

[Ed C.]

I have that book too, and found that part. It says "The round ball as it drops from the mould should be the bore diameter minus one thickness of the patch material".
That would work good, and not be overly tight I think.

OK, thank you. Now that makes sense! Nice to see the exact quote.

 

[M. De Land]

I have that book too, and found that part. It says "The round ball as it drops from the mould should be the bore diameter minus one thickness of the patch material".
That would work good, and not be overly tight I think.

I'm reading the book as I type (page 417) this and if your bore is .400 across the lands and your patch material is .009 then the ball Brockway not Roberts recommends is .409 diameter for the best accuracy that barrel is capable of ! That's bore diameter "Plus" patch thickness not minus for optimum accuracy. Keep in mind the grooves were often .006-.010 deep per side (that's .012 to .020 total groove depth) which has to be filled with patch material so as not to allow gas blow by and patch rupture or burn through.
It's not a misprint either as he proscribes the same formula further down the page for picket or sugar loaf bullet using a cloth patch.
As cloth patch use declined to paper patching and then grease groove bullets the groove depth and land style both changed profile and got more shallow.

 

[M. De Land]

It's been a long time since I read the book so this post probably has some misunderstandings in it.

My memory suggests that the competitions of the time were shot with bullets rather than balls. Maybe they were called picket bullets apparently the widest point point of the bullet was the base and the were shot with a patch.

View attachment 237309

They had to be loaded with a false Muzzle and it had to be done perfectly. Based on the results possible with these they must be capable of exceptional accuracy but I think that any minor deviation loading would be inaccurate.

Regarding measuring the patch, the very tight fit was probably not too difficult to load with his formula given the small surface being compressed.

Yes, they used ball as well as picket bullet, sugar loaf bullets and two piece soft base .hard nose bullets usuaully swaged after casting for best accuracy. Later on they developed the Luvern style bullets with many grease grooves down the bullet shank and no patch for cartridge shooting, bullet seated from the muzzle.