12 bore worn barrel.

[TOPGUN749]

I have an old side by side which was made in Birmingham about 1895 as close as we know,Chris Cradock once said 1894-1900, steel 30 inch barrels,hammerless, black powder proof. It was my Grandfather’s and he got it second hand,I haven’t used it for years. Today I obtained a set of proof gauges,and found the left barrel worn 10 thou + The original proof was 13/1 meaning .719 inches,and now the left barrel is .729+ 

I wonder how many cartridges it would have taken to wear 10 thou of steel? Or I wonder if the guns of that era were not ever made to close tolerances and it wasn’t actually.719 when new? The right barrel which is true cylinder shows within proof (for BP) even though stamped the same 13/1.

Edited October 10 by TOPGUN749

[enfieldspares]

It depends how long ago Grandad acquired it? It may be that in fact it has had the barres lapped out before he got it? Or, of course, the the Rules of Proof meant that a barrel at .728 would have been stamped up as 13/1 as far as I believe? In which case the wear is a lot less than you'd think. So I think you are correct in what you suggested. There are others on P/W will know better than I regarding 13/1 and the largest that a bore could be to still be marked as 13/1.

Edited October 10 by enfieldspares

[TOPGUN749]

6 minutes ago, enfieldspares said:

It depends how long ago Grandad acquired it? It may be that in fact it has had the barres lapped out? Or, of course, the the Rules of Proof meant that a barrel at .728 would have been stamped up as 13/1 as far as I believe? There are others on P/W will know better than I regarding 13/1 and the largest that a bore could be to still be marked as 13/1.

It was in the family almost from new we believe my great uncle had it,then my grandfather,then my Dad,certainly wasn’t used a lot in the past 60 years as we couldn’t afford a lot of cartridges! Never been lapped out,and has pitting now which was there 50+ years to my knowledge caused by black powder and not cleaning properly I expect. 13/1 is the .719 proof mark,12 is the .729 mark.

Edited October 10 by TOPGUN749

[JohnfromUK]

16 minutes ago, TOPGUN749 said:

13/1 is the .719 proof mark,12 is the .729 mark.

That is correct.  The bores were 'measured' with a 'go/no go plug gauge' set - the size stamped being the largest plug that would pass (I believe 9" from the breech face)

So - a gun stamped 13/1 - the .719 gauge passed, but the .729 did not - therefore a bore of between .720 and .729

a gun stamped 12 - the .729 gauge passed, but the .739 did not - therefore a bore of between .730 and .739

As said above - the gun could have started life as high as .728 and still been marked 13/1 at the time of proof.

[TOPGUN749]

14 minutes ago, JohnfromUK said:

That is correct.  The bores were 'measured' with a 'go/no go plug gauge' set - the size stamped being the largest plug that would pass (I believe 9" from the breech face)

So - a gun stamped 13/1 - the .719 gauge passed, but the .729 did not - therefore a bore of between .720 and .729

a gun stamped 12 - the .729 gauge passed, but the .739 did not - therefore a bore of between .730 and .739

As said above - the gun could have started life as high as .728 and still been marked 13/1 at the time of proof.

Thank you for that info which I agree with,yet if a 13/1 barrel nominally .719 was manufactured at .728,it would then have only 1 thou of wear limit before being ‘out of proof’ which goes against the 10 thou ruling really.

[JohnfromUK]

14 minutes ago, TOPGUN749 said:

Thank you for that info which I agree with,yet if a 13/1 barrel nominally .719 was manufactured at .728,it would then have only 1 thou of wear limit before being ‘out of proof’ which goes against the 10 thou ruling really.

Yes, but that's how the system worked.  I don't believe accurate and reliable internal gauges were available when proof rules were originally written (early 19th century?), so they were written around plug gauges - which were accurate and repeatable.

It is quite common to see guns originally proofed as 13/1 in reproof at 12 - and still have decent wall thickness, suggesting little has been bored out.

[TOPGUN749]

1 minute ago, JohnfromUK said:

Yes, but that's how the system worked.  I don't believe accurate and reliable internal gauges were available when proof rules were originally written (early 19th century?), so they were written around plug gauges - which were accurate and repeatable.

It is quite common to see guns originally proofed as 13/1 in reproof at 12 - and still have decent wall thickness, suggesting little has been bored out.

Maybe that explains it,and the left barrel was manufactured larger than the right yet both stamped for .719. If this happened with more modern guns say from post war many would be deemed out of proof much before their time.,rather unfortunate.

[enfieldspares]

1 minute ago, JohnfromUK said:

Yes, but that's how the system worked.  I don't believe accurate and reliable internal gauges were available when proof rules were originally written (early 19th century?), so they were written around plug gauges - which were accurate and repeatable.

It is quite common to see guns originally proofed as 13/1 in reproof at 12 - and still have decent wall thickness, suggesting little has been bored out.

This +1. I had maybe ten plus years ago an old 1925 or so BSA that was stamped as 13/1 and in fact was at the other end of the scale. That is to say they were .729" when measured. So it was by just that one thousandth of an inch and marked at 13/1 and not the lesser diameter stamp.

[TOPGUN749]

2 minutes ago, enfieldspares said:

This +1. I had maybe ten plus years ago an old 1925 or so BSA that was stamped as 13/1 and in fact was at the other end of the scale. That is to say they were .729" when measured. So it was by just that one thousandth of an inch and marked at 13/1 and not the lesser diameter stamp.

So meaning your BSA was effectively out of proof if the .729 plug gauge would pass at 9 inches from the breach, as I understand the rule.

[enfieldspares]

Just now, TOPGUN749 said:

So meaning your BSA was effectively out of proof if the .729 plug gauge would pass at 9 inches from the breach, as I understand the rule.

No. Oops! I got distracted. And hit the wrong key. The gun was .720" when measured. 

[JohnfromUK]

I have a Henry Atkin, original barrels.  It was originally proofed at 13/1 (.719) in nitro in around 1911.  It has been later re proofed at 12 (.729) with no other changes (i.e. no chamber lengthening or similar).

Currently measures .731 in both barrels, both with 30 thou minimum wall thickness.  This wall thickness makes it unlikely much has been removed

[TOPGUN749]

14 minutes ago, enfieldspares said:

No. Oops! I got distracted. And hit the wrong key. The gun was .720" when measured. 

That’s reasonable,only 1 thou over,plenty of life left before reaching the 10 thou limit!

[TOPGUN749]

16 minutes ago, JohnfromUK said:

I have a Henry Atkin, original barrels.  It was originally proofed at 13/1 (.719) in nitro in around 1911.  It has been later re proofed at 12 (.729) with no other changes (i.e. no chamber lengthening or similar).

Currently measures .731 in both barrels, both with 30 thou minimum wall thickness.  This wall thickness makes it unlikely much has been removed

Guess that means it wore a few thou from 1911 to the reproof,making it .729 second time round,and since then maybe a fraction more,but still got 9 thou left to play with should it ever get used to that extent,probably never likely!

[JohnfromUK]

6 hours ago, TOPGUN749 said:

Guess that means it wore a few thou from 1911 to the reproof,making it .729 second time round,and since then maybe a fraction more,but still got 9 thou left to play with should it ever get used to that extent,probably never likely!

My own guess (and it is only that since all this happened before my ownership) is that it was originally proofed (London, 1911) between .720 and .729, then at some stage has been lapped and/or fine bored, very probably to remove a bit of pitting taking it to .731 thus needing re-proof which was done in the London Proof House - and it remains at that today.  At .731, it would have been marked 12 taking the .729 plug gauge, but not the .739.

Barrel wear in normal use is very, very low and usually metal removal is due to lapped and/or fine boring. 

There was a set of barrels (made by Boss & Co?) used testing cartridges at the Proof House (or was it at Eleys?) that is known to have fired a huge number of cartridges over a great many years with minimal true 'wear'.  I cannot find the article now, but it has been documented.

[TOPGUN749]

1 minute ago, JohnfromUK said:

My own guess (and it is only that since all this happened before my ownership) is that it was originally proofed (London, 1911) between .720 and .729, then at some stage has been lapped and/or fine bored, very probably to remove a bit of pitting taking it to .731 thus needing re-proof which was done in the London Proof House - and it remains at that today.  At .731, it would have been marked 12 taking the .729 plug gauge, but not the .739.

Barrel wear in normal use is very, very low and usually metal removal is due to lapped and/or fine boring. 

There was a set of barrels (made by Boss & Co?) used testing cartridges at the Proof House (or was it at Eleys?) that is known to have fired a huge number of cartridges over a great many years with minimal true 'wear'.  I cannot find the article now, but it has been documented.

Thank you for you input and knowledge,I am surprised my old sidelock showed such a difference between the 2 barrels. If I get the chance to measure with a dial micrometer at 9 inches from the breach I will just out of curiosity. From how it looks using my Newboult & Thorp plug gauges I believe the right barrel to probably measure.723 and the left .729 .
If the manufacturers had only used mid way plugs such as .724 they could have produced barrels more accurately and hence allow for the wear tolerance before being out of proof.(As it is passing a proof at one thou within proof still seems possible,though it’s rare I guess)

[JohnfromUK]

28 minutes ago, TOPGUN749 said:

I am surprised my old sidelock showed such a difference between the 2 barrels.

The most likely reason for a big difference is probably due to pitting removal.  A little more metal may have been removed in one barrel.  It used to be common (in days when cartridges left a more corrosive residue) to 'tidy up' the barrels when any work was done.  Pitting (because it harbours corrosive residue that can't be cleaned out of the actual pits) was usually removed where reasonably possible.

I have a sleeved gun that is .729 right and .734 left.  I'm guessing it was made that way as to the best of my knowledge (I have owned it for around the last 40 years and it was probably sleeved a few years before I bought it) it has never had any work done since sleeving and shows no pitting in either barrel.  It is proofed at 12, so the .729 barrel must be 'as proofed', and there is no reason to think that one barrel alone has needed work.

[enfieldspares]

1 hour ago, JohnfromUK said:

My own guess (and it is only that since all this happened before my ownership) is that it was originally proofed (London, 1911) between .720 and .729, then at some stage has been lapped and/or fine bored, very probably to remove a bit of pitting taking it to .731 thus needing re-proof which was done in the London Proof House - and it remains at that today.  At .731, it would have been marked 12 taking the .729 plug gauge, but not the .739.

Barrel wear in normal use is very, very low and usually metal removal is due to lapped and/or fine boring. 

There was a set of barrels (made by Boss & Co?) used testing cartridges at the Proof House (or was it at Eleys?) that is known to have fired a huge number of cartridges over a great many years with minimal true 'wear'.  I cannot find the article now, but it has been documented.

 I remember the same article. Supposedly the gun use was to check choke patterning performance of sample loaded cartridges against paper pattern boardson Kynoch's forty yard range and the figure quoted for the number of cartridges fired was three million. But I also have in my mind that the gun itself was on its third set of barrels?

[TOPGUN749]

1 hour ago, JohnfromUK said:

The most likely reason for a big difference is probably due to pitting removal.  A little more metal may have been removed in one barrel.  It used to be common (in days when cartridges left a more corrosive residue) to 'tidy up' the barrels when any work was done.  Pitting (because it harbours corrosive residue that can't be cleaned out of the actual pits) was usually removed where reasonably possible.

I have a sleeved gun that is .729 right and .734 left.  I'm guessing it was made that way as to the best of my knowledge (I have owned it for around the last 40 years and it was probably sleeved a few years before I bought it) it has never had any work done since sleeving and shows no pitting in either barrel.  It is proofed at 12, so the .729 barrel must be 'as proofed', and there is no reason to think that one barrel alone has needed work.

The gun has been in the family since around 1920 we think,and very unlikely to have had any barrel work done in those 100 years. The barrels are both pitted mostly in the half nearest the muzzle and have been since the late 1960’s when I took an interest.There are also a couple of minor dents been there for decades. 
Anyway it is retired now,would never pass a reproof due to pitting needing removal and barrels becoming thinner as a result plus dent removal needed.Costs definitely not worth it!  It has 2 3/4 chambers and was used until about 30 years ago with up to 32 gram cartridges. Main proof marks are BV BP.

Edited October 11 by TOPGUN749

[London Best]

I remember reading an article about the Boss gun in the Eley test department. The figure I remember quoted was one and a quarter million rounds with no measurable wear. 
Barrels wear through being lapped or fine bored as has been said. 
The next proof size after 12 (.729) is, I believe, 12/1 (.740, not .739).

[TOPGUN749]

1 hour ago, London Best said:

I remember reading an article about the Boss gun in the Eley test department. The figure I remember quoted was one and a quarter million rounds with no measurable wear. 
Barrels wear through being lapped or fine bored as has been said. 
The next proof size after 12 (.729) is, I believe, 12/1 (.740, not .739).

Yes,.740 for a .729 proof, and .751 for a .740 proof.

[JohnfromUK]

23 minutes ago, TOPGUN749 said:

Yes,.740 for a .729 proof, and .751 for a .740 proof.

I stand corrected!

[Fil]

2 hours ago, London Best said:

I remember reading an article about the Boss gun in the Eley test department. The figure I remember quoted was one and a quarter million rounds with no measurable wear. 
Barrels wear through being lapped or fine bored as has been said. 
The next proof size after 12 (.729) is, I believe, 12/1 (.740, not .739).

Absolutely correct LB. Barrels do not get shot thin. It's all from Repair work. And 12/1 is .740 then 11 which is .751

If anyone is interested I have the complete list from 28 (.550) all the way up to 8/2 (.860) I rote it all down in my little book when I was an apprentice 40 years ago. 

[Fil]

12 hours ago, JohnfromUK said:

Yes, but that's how the system worked.  I don't believe accurate and reliable internal gauges were available when proof rules were originally written (early 19th century?), so they were written around plug gauges - which were accurate and repeatable.

It is quite common to see guns originally proofed as 13/1 in reproof at 12 - and still have decent wall thickness, suggesting little has been bored out.

Spot on John. Plug gauges were the go to for proofing due to the availability of dial bore gauges. Top quality Chubb gauges are now used but plug gauges are still used by some London makers I've worked for. As they use to say, "The plug never lies!"

Does anyone remember the Miroku o/u's coming over from Japan that had Birmingham proof marks stamped on them reading .719? A lot of them actually measured around .726 - .727 but the proof house stamped them down as they were not up to the required .728 bore size to get stamped .728. So they effectively only had 1 or 2 thou proof life left in them. Seen loads. Most all have been retired by now but worth keeping in mind if you are looking to buy an old one. 

[Vince Green]

As London Best said

It's impossible in ordinary use to wear ten thou out of a barrel but lapping was common in the days of corrosive primers pre WW2

[Fil]

On 19/10/2024 at 23:38, Vince Green said:

As London Best said

It's impossible in ordinary use to wear ten thou out of a barrel but lapping was common in the days of corrosive primers pre WW2

And black powder. I still lead lap my barrels today. Whether it's boring a new barrel, pitting or cleaning up after a dent. Also for choke work.