barrel tester

[Roger Fisher]

Bookie,

I'm curious, could you explain how a barrel can crystallize, and what that means?

Michael

Thanks Bookie for the detailed response.  It points out that 'handmade' breeching etc not the better way..  I now feel somewhat vindicated in my own testing!   I say somewhat!!   I'm too embarassed to state what my testing method is!!   Well $#*! why not!  I take the finished rifle or smoothy to my favorite hemlock (tree that is) loaded (the gun not me) reach around said tree double load double ball and fire her off in to the embankment!  I trust my work that much

Yes, I did say finished rifle/smoothy!!  Dumb I guess; but as I said I trust my work and I shootm myself (no customers) I couldn't find anyone dumb enough to want any of my 'boat oars'!!!!!!!!!

[Steve Bookout]

Hi Michael!  The Remington barrel that was mentioned was an old barrel that had been cast at Remington's foundry sometime around 1870.  It being cast, had no grain structure.  The barrel was then sold and the rifle maker rifled it.  The 7 grooves were around .007 " deep.  The metal aged and became brittle over the years.  A hairline crack started at a corner of one of the grooves, evidentily near the breech end, eventually progressing the entire length of the barrel.  The black powder residue left after firing slowly ate into the metal speeding the decaying process.  Then around a hundred and forty years later, some fatboy made a repair on it and blew it up.  The acids from the black powder reside & rust either magnifyed or at least made the crystalization stand out and it is readily observed on the barrel remanents with the naked eye.  The crack in some places was less than 1/32" from the outside of the barrel in some places.  That would indicate the barrel had been decaying for many, many years.  I am very glad the barrel blew and not as he was firing it.  Hope this helps explain the issue.  I am a dyed in the wool believer of proofing any barrel, old or modern, that I have worked on concerning the breech, drum, and  vent.  Cheers, Bookie

[Steve Bookout]

Hi Roger!  I have used exactly the same method of proofing myself and i expect that we are not a small, exclusive club!  I trust my work as well, but I have scraped some finish off from time to time.  Thatwas quite upsetting to say the least.  That led me to making a proofer back in 1991.  It was featured in Muzzle Blasts years ago.  Since that time, it gets used 100% of the time.  I breech most of my barrels and when I do, that means by hand.  It is not quickly done.  I also have a sooper-dooper custom hand made 5/8" breech drill bit that leaves a square shoulder and thus can't be made to go too deep.  That gives me some extra good feeling about my work.  Used it on my smooth rifle trade gun last summer.  Works like a charm.  Cheers, Bookie

[Bruce]

     Am ready to proof my .50 cal. barrel.  Using FFFG how many grains should I use and how many proof firings?                       BHB

[Tony Clark]

Hi Michael!  The Remington barrel that was mentioned was an old barrel that had been cast at Remington's foundry sometime around 1870.  It being cast, had no grain structure. 

Bookie, I'm not certain what your intended meaning is by describing this barrel as being "cast", but just so that others reading this may not misunderstand what the term "cast steel" refers to when stamped on and old Remington barrel like your describing, or many other objects that were produced around this time period, it means that the item was manufactured from cast (later referred to as crucible) steel, and is in fact not a casting in and of itself. To my knowledge Remington did not have a foundry which produced cast steel. Rather, Mr. Remington was one of the first people to use "cast steel" to produce rifle barrels by drilling a blank of bar stock which initially had been produced by the crucible process. This type of cast steel did in fact have a grain structure much as the modern steels one uses have, which are all "cast steel", and which are a result of the processes used to shape the cast steel into its final form such as bar, round, or flat etc. Regards, TC

[Jerry V Lape]

I am somewhat amazed that those proofing their barrels are just looking to see if they get a catastrophic failure.  Professional proof of barrels, as done in countries where proof is regulated by law, they are looking for any indication the metals elastic limits are being exceeded.  Barrels are carefully measured for critical dimensions before firing with the proof load.  Then they are carefully remeasured at the exact same locations.  If the elastic limit has been exceeded the barrel will have larger measurements.  (This is measured in to one ten thousandth of an inch or less. )  If the barrel got larger it fails. If the barrel's elastic limits were not exceeded the barrel would return to original dimensions once cooled back to ambient.   The proof is usually fired more than once unless failure occurred on the first firing.  Proof process begins with detailed inspection of all the components which would deal with things like poorly done vent liners etc.  Any errors found in the inspection gets a rejection w/o firing.   Simply firing an overload only tells you the barrel assembly survived that particular firing.  If the elastic limit was exceeded you are now setup for further stretching over the days or years thereafter until catastrophic failure finally is achieved.  If the elastic limit was not exceeded by the proof load, then you have a reasonable expectation the barrel, if maintained correctly, can be fired repeatedly with normal service loading without significant hazard.  Service loads are significantly less than the proof load which is carefully prescribed by regulations.    I will have to admit Bookie's experience indicates significant problems avoided.  However, if you don't understand the concept of elastic limits you may be way overly confident in your proof process.  

[Benedict]

I am somewhat amazed that those proofing their barrels are just looking to see if they get a catastrophic failure.  Professional proof of barrels, as done in countries where proof is regulated by law, they are looking for any indication the metals elastic limits are being exceeded.  Barrels are carefully measured for critical dimensions before firing with the proof load.  Then they are carefully remeasured at the exact same locations.  If the elastic limit has been exceeded the barrel will have larger measurements.  (This is measured in to one ten thousandth of an inch or less. )  If the barrel got larger it fails. If the barrel's elastic limits were not exceeded the barrel would return to original dimensions once cooled back to ambient.   The proof is usually fired more than once unless failure occurred on the first firing.  Proof process begins with detailed inspection of all the components which would deal with things like poorly done vent liners etc.  Any errors found in the inspection gets a rejection w/o firing.   Simply firing an overload only tells you the barrel assembly survived that particular firing.  If the elastic limit was exceeded you are now setup for further stretching over the days or years thereafter until catastrophic failure finally is achieved.  If the elastic limit was not exceeded by the proof load, then you have a reasonable expectation the barrel, if maintained correctly, can be fired repeatedly with normal service loading without significant hazard.  Service loads are significantly less than the proof load which is carefully prescribed by regulations.    I will have to admit Bookie's experience indicates significant problems avoided.  However, if you don't understand the concept of elastic limits you may be way overly confident in your proof process.  

Your comments are right on.  I have been concerned about the issue that the catastrophic testing that is commonly done being merely the first step in CAUSING a failure but did not know what to do about it.  I know that historically, proof testing was not much more than firing an overload and checking for catastrophic failure.  The question that comes up is what is a practical method for us to use in testing our work.  Not many of us have the tools to measure that accurately.  Even with my micrometer, I would be unsure that I could measure the same location accurately enough to detect a change of one ten thousandth.  Just a slight difference in location on a swamped barrel could account for that.   Does any one have any suggestions?

Bruce

[T*O*F]

Professional proof of barrels, as done in countries where proof is regulated by law, they are looking for any indication the metals elastic limits are being exceeded.  Barrels are carefully measured for critical dimensions before firing with the proof load.

As a matter of information, the proofing of barrels in England has been done hydraulically for many years.  Powder loads are no longer used.  Robin or Feltwad should be able to confirm this.  Since the technology exists, I'm sure that other countries do likewise.

[Jerry V Lape]

TOF, I think you are misinformed regarding hydraulic testing.  Producing the pressure curve within a barrel with the peak spike occuring in the chamber area followed by decaying pressures up the barrel would be a very length procedure at best.  Certainly can't subject the thin muzzle end of a barrel to the peak pressure which occur in the stout breech area as in modern shotguns.   Something a proof load with more than a century of experience behind it does quite easily, reliably, cheaply.  It is hard to imagine a need to go to a more complex and expensive system to simulate a real shot.   

Perhaps you are thinking of the change from the older lead crusher system (LUP) or copper crushers (CUP) being replaced by strain gauge pressure measurements as used on checking ammunition for comformance to CIP standards.  The strain gauge setups are typically calibrated using hydraulic pressure.  But actual proofing of a barrel is still done with cartridges designed to produce overload pressures in accordance with CIP procedures to which most of Europe and other countries around the world adhere.  US does not conform to these protocols but relys on manufacturers to comply with SAAMI standards (and the absolute threat of lawsuit for failure to produce safe products accordingly.

If one of you more tecnically minded individuals wished to start a business proofing barrel assemblies (especially blackpowder barrels) you might just find yourself with a nice little profit.  Make sure you have adequate insurance!!!

[Steve Bookout]

BHB, Because of liability lawsuits, no one in their right mind is going to tell you what to use.  They would have no idea of how well your barrel system was made/assembled.  If you were to observe me going through the proofing gyrations that I do, you'd see the barrel proofed only ONE time with double the normal powder charge.  I will not reccommend anyone trying to proof a barrel unless there is some contrivance to secure the barrel in a safe manner such as the device that Hoot Al has shown earlier.  This is always dangerous work and it's a long way to the hospital from the range...particularly if you can't drive yourself there. Safety is paramount.  If you don't know what you're about, don't do it.  This is not intended to be a snide reply, just a friendly caution a bit on the heavy side.    Cheers, Bookie

[Madcaster]

 I think that is a great ideal of preventing steel pieces from flying around so much too!

[Ken G]

Madcaster,
That's exactly why I installed the hinged lid on mine.  I did not like the thoughts of pieces flying like shrapnel.  I plan to install an additional piece that flaps down behind the breechplug.  It may not completely stop something from flying loose but it will have much less velocity after going through a 1 inch piece of pine.  Maybe it's overkill but I feel safer.  For me and any any bystanders. 

Ken

[Jerry V Lape]

Or maybe the wood covering adds a lot of flying splinters to the shards of steel when a barrel fails catastrophically?  Sand bags would be much more effective at containing the failures.