So i'm hooked!!!

[Victor3]

what cast bronze barrel are you thinking about ??

 Dan, I'm remembering pictures of bulged/cracked bronze barrels posted in the past. I think it was Boom J who had them(?) Also, I remember M&T had a small one they tested which failed.

 I can't remember many details about them...

[Victor3]

Absent any better guidelines, I will stick with N-SSA guidelines.   It's an individuals choice what guidelines to use.  

 But DD, better guidelines are not absent.

 We can (and should, if long-term safety really is #1) choose to build only liners/barrels that are properly constructed using proven welding processes, correct shrink-fits and of sufficient wall thickness to contain chamber pressures with a generous safety factor. All of those aspects are absent within the N-SSA rules, along with a blessing of the antiquated and inferior cast iron (as opposed to much safer modern steel) barrels that the majority of their membership uses.

 I'm sorry, but the wisdom in directing someone new to cannons to the N-SSA rules in order to construct a safe cannon barrel escapes me.

 As far as the "one caliber rule" (of thumb) is concerned, it's a good one IMO. However, only if the materials, design and construction of the barrel components are more sound than the N-SSA requires.

[Double D]

Absent any better guidelines, I will stick with N-SSA guidelines.   It's an individuals choice what guidelines to use.  

 But DD, better guidelines are not absent.

 We can (and should, if long-term safety really is #1) choose to build only liners/barrels that are properly constructed using proven welding processes, correct shrink-fits and of sufficient wall thickness to contain chamber pressures with a generous safety factor. All of those aspects are absent within the N-SSA rules, along with a blessing of the antiquated and inferior cast iron (as opposed to much safer modern steel) barrels that the majority of their membership uses.

 I'm sorry, but the wisdom in directing someone new to cannons to the N-SSA rules in order to construct a safe cannon barrel escapes me.

 As far as the "one caliber rule" (of thumb) is concerned, it's a good one IMO. However, only if the materials, design and construction of the barrel components are more sound than the N-SSA requires.

Okay who publishes these better guidelines for blackpowder muzzleloading cannon?  Where do you find them?  Where are the N-SSA rules insufficient?  

When have we ever said to use a cast iron barrel with out a liner?  Please point to it!

 

The N-SSA rules give no indication of what type of steel should be used. It could be assumed (from their wording) to be any type as long as it's "extruded seamless steel tubing of a minimum ANSI standard and of a minimum 3/8-inch wall thickness." What "minimum ANSI standard" are we talking about here? They're hardly the same for all types of seamless steel tubing.

I looked up the ANSI standards for extruded steel tubing---well I tried, it’s a $38 PDF Down load, so I don’t have it.  So absent those Minimum ANSI standards it’s not possible for us to say the N-SSA rule is weak.  

Can you cite any extruded steel seamless tubing available on the U.S. market that meets minimum ANSI standards that is unsafe for use as a cannon barrel liner?

Also, their breech plug specs are nebulous; "sweat-fitted into the liner and welded." We of course assume that to mean shrink-fitted, but no indication is given as to either the interference fit tolerances nor what manner of welding should be employed. They require pictures of before and after welding (only on barrels manufactured after 3/1/86 though), but pictures show next to nothing as far as the soundness of a shrink fit or weld. They say that the plug must be a minimum of 1" thick, but we know that the force applied to a 4" diameter plug is far greater than that of a 2" plug at the same internal pressure.

The description of the breech plug installation is nebulous, how? Because they use archaic terms and phraseology and not the modern “computer” call out system.   Modern computer controlled machines require every single detail to be called out, because the machines can’t think, men can.   There was a time  when a machinist or welder was told to do something and they knew how to do.   That’s when these N-SSA rules were written.


 

They don't even require a liner or the "one caliber rule" on original CW era barrels (probably more subject to failure than most modern-made guns) or reproductions approved prior to 3/1/86 unless they fail some "inspection" which isn't defined in the text. Is it done by a guy with a flashlight or are more sophisticated methods employed?

That’s called a Grandfather rule.  By requiring new guns and those old guns that fail to meet inspection to meet the new N-SSA standards they are increasing the safety standards of the gun.  

 

Although their record of safety speaks for itself, I'm not all that impressed with the N-SSA's wording on how to construct a uniformly safe liner/barrel.

You are right the rules do need updated using more modern terminology, but frankly I can’t find fault in the mechanics described.  I also am unaware of any other standards for safe cannon construction, are you?

I know at one time one of our regular contributors, Artilleryman was going to present  the need to update the rules to the N-SSA board.  I don’t know what happened with that.

If the sole fault you find in the N-SSA is the wording, I agree.  But the premise is sound.

  

[Victor3]

"Okay who publishes these better guidelines for blackpowder muzzleloading cannon?  Where do you find them?" Where are the N-SSA rules insufficient?

 I never said they were published anywhere, just that " better guidelines are not absent." The lack of one specific document detailing important specifics on building safe barrels doesn't mean we should go to one that has glaring omissions and invalid specs such as those I've already noted in the N-SSA's.

 Once again...

We can (and should, if long-term safety really is #1) choose to build only liners/barrels that are properly constructed using proven welding processes, correct shrink-fits and of sufficient wall thickness to contain chamber pressures with a generous safety factor. All of those aspects are absent within the N-SSA rules, along with a blessing of the antiquated and inferior cast iron (as opposed to much safer modern steel) barrels that the majority of their membership uses.

 Do you find fault with the above at some specific point?

"When have we ever said to use a cast iron barrel with out a liner?  Please point to it!"

 Excuse me, but where did I ever imply that "we" (or anyone other than the N-SSA) ever said any such thing? I didn't.

"Can you cite any extruded steel seamless tubing available on the U.S. market that meets minimum ANSI standards that is unsafe for use as a cannon barrel liner?"

 Again, what "minimum ANSI standard" are we talking about? They all meet some minimum ANSI standard, but not all meet what would be considered a minimum strength requirement for a barrel liner.

 None of them are any good unless they're of sufficient wall thickness, tensile/yield, etc. strength and diameter to contain chamber pressure with a healthy safety factor. As I've already noted, a 3/8" wall liner per N-SSA rules in a cast iron Napoleon isn't.

"The description of the breech plug installation is nebulous, how? Because they use archaic terms and phraseology and not the modern “computer” call out system.   Modern computer controlled machines require every single detail to be called out, because the machines can’t think, men can."

 I fail to see how computers are relevant this discussion. Words, welds and dimensions are the same now as they were 50 years ago.

 It's nebulous because as I said before, the N-SSA gives no information as to how to acheive the "sweat" (shrink) fit or weld required to have the required strength, and states that all plugs must be a minimum of 1" thick (which is completely insufficient when you get into the larger diameter bores).

"There was a time  when a machinist or welder was told to do something and they knew how to do.   That’s when these N-SSA rules were written."

 Absolutely! There indeed was a time. So DD, how many times have you directed a man, new to cannon fabrication, to the N-SSA rules for guidance? Someone who today has to determine what the heck the rules really mean in order to accomplish a safe build? Could you do it if you had no other knowledge or skills in cannon building? Not many are accomplished machinists & welders and even if one is, it doesn't mean he can make a safe liner or barrel without detailed instructions and guidance absent in the N-SSA .pdf.

"That’s called a Grandfather rule.  By requiring new guns and those old guns that fail to meet inspection to meet the new N-SSA standards they are increasing the safety standards of the gun."

 Correct. Per the N-SSA rules, old (Grandfathered) cast iron cannons don't have to be as safe as new ones (no liners or one caliber rule required as long as they pass some unspecified inspection). Makes perfect sense.

"You are right the rules do need updated using more modern terminology, but frankly I can’t find fault in the mechanics described."

 The mechanics are not fully described, and in some cases as I've previously noted are lousy from an engineering standpoint.

"I also am unaware of any other standards for safe cannon construction, are you?"

 I am unaware of any safe published standards, including those of the N-SSA. I'm not willing to bet my life or anyone else's on (IMO) inferior standards just because that's all that are available, published in some association's document. I'll stick with sound engineering principles and overbuilding with correct materials.

"If the sole fault you find in the N-SSA is the wording, I agree. But the premise is sound."

 The fault I find isn't only with wording that's there; it's a lack of wording that leaves too much to be assumed.

[Double D]

I think we are now beginning to debate in circles...

[Double D]

Victor,

You question about the minimum ANSI Standard for extruded steel  tubing is an answer I would like t hear also.  Have  you consider posting you question on their forum. http://n-ssa.org/phpBB3/

[VA Rifleman]

Gentlemen.

Excuse me for butting in.

Without a doubt, the collective wisdom of this forum could develop very good design standards for modern cannon builds and evaluation of existing tubes. These standards could also explain the "why" to go along with the "what". Found that once people understand the "why", they are more prone to buy in.

Once in draft, a peer reviewed could be conducted by those most knowledgeable. Perhaps someone from the NSSA would be appropriate if the politics or competing agendas doesn't throw a monkey wrench into the works. The senior forum members would know better then I.

Just a thought.
Respectfully,
Va Rifleman

[Victor3]

Victor,

You question about the minimum ANSI Standard for extruded steel  tubing is an answer I would like t hear also.  Have  you consider posting you question on their forum. http://n-ssa.org/phpBB3/

 DD,

 I'm not interested in what they consider to be the minimum standard for their liner tubing.

 There's no commonly available 3/8" wall seamless steel tubing that could (IMO) be considered safe to make a liner from for most CW profile cast iron barrels with a bore over 3".

 Regardless, the point is academic considering that their stated minimum breech plug thickness and fabrication requirements can account for less strength than the liner wall.

[Double D]

Victor,

That's a very emphatic statement.   You say that like you know what the  numbers are for extruded seamless tubing.  Would you share those numbers with us?

[KABAR2]

I think the only way to test something like this would be to do destructive testing on the liner with breech plug in place
with the proper equipment in place to measure the pressures developed up to and including the point of failure,
once you have a set of values set for the liner and the fail point then you can add the cannon material of your choice
iron, bronze, steel,  and do the test again until the whole unit fails,  it will most likely take much more to create
a failure in a lined cannon than just a liner so once you have this info you could extrapolate to other size cannon,
and these tests should be done on the most common bore sizes.

So who wants to go for the guberment grant for this?

[Victor3]

 Gladly, DD.

 Let's take condition HT-125 cold drawn seamless 4130 aircraft alloy structural tubing, MIL-T-6736 as an example. Strong, weldable with common processes and available from many sources (P. 116 from my Jorgensen catalog here).

Tensile - 125 ksi
Yeild - 100 ksi
Elongation - 12% in 2"

 Ideal stuff for a cannon liner. If you have any more questions, just let me know. 

 

[dominick]

Victor,  Beings you're from southern California, you just don't know how to speak fluent hillbilly.   That's why you're struggling over a simple term like "sweat fit".  Here's the definition of sweat fit.      "SWEAT FIT"  Ya gitcha big ole hammer from the tool box and ya beat on that plug til ya sweatin!  Sweatfit. 

[Cat Whisperer]

Bruce -

This is something that would be cool to do.  I've thought about it for many years.  For a few years I was a tooling engineer, designing and maintaining dies for use in 30 to 80 ton presses.  Lots of issues have what appear to be simple answers -  unitl some time down the road and you have to come up with a better solution.

We've taken the safe approach here.  (I'm NOT advocating that we STAY where we are, we all need to grow.)
The simple yet safe approach has been to endorse the practices that have been proven safe by many cannons/people/years in practice - namely those practices developed by the N-SSA and AAA.

Undoubetedly, something will develop.  Perhaps one of us will compile a CD of articles?   

Gentlemen.

Excuse me for butting in.

Without a doubt, the collective wisdom of this forum could develop very good design standards for modern cannon builds and evaluation of existing tubes. These standards could also explain the "why" to go along with the "what". Found that once people understand the "why", they are more prone to buy in.

Once in draft, a peer reviewed could be conducted by those most knowledgeable. Perhaps someone from the NSSA would be appropriate if the politics or competing agendas doesn't throw a monkey wrench into the works. The senior forum members would know better then I.

Just a thought.
Respectfully,
Va Rifleman

[Victor3]

Victor,  Beings you're from southern California, you just don't know how to speak fluent hillbilly.   That's why you're struggling over a simple term like "sweat fit".  Here's the definition of sweat fit.      "SWEAT FIT"  Ya gitcha big ole hammer from the tool box and ya beat on that plug til ya sweatin!  Sweatfit. 

 Well shazaaaam, Dom. That there clears it up rat now don't it!

 Just last week the doc were askin' me 'bout my post operative. I still don't know what the mailman has ta do with it...

[dan610324]

 

the idea to write a completely new building instruction is a good one .
anyone who got the time to start a new "safety in cannon building" topic

when we here agree to the new instruction it could be sent to both n-ssa and aaa for further comments
maybe it could be a new national safety instruction used by all cannoners in usa .

what do you think guys ??

[Victor3]

Without a doubt, the collective wisdom of this forum could develop very good design standards for modern cannon builds and evaluation of existing tubes. These standards could also explain the "why" to go along with the "what". Found that once people understand the "why", they are more prone to buy in.

 VA rifleman,

 I'd like to see that, but as has been proclaimed...

It to hazardous to assume every one here has an engineer's knowledge.

 So I don't know that it will happen.

 I've posted my concerns here in the hope that some may (as I have) critically examine the N-SSA's standards of what constitute a safe cannon barrel and in the interest of safety, to encourage others to go beyond what they require.

 If the interest is primarily concerning legal exposure, I fully understand the desire to point to someone else's standard in order to remove oneself from the equation. I'm often required to do so when providing depositions on industrial accident cases, always referring back to OSHA and/or other standards whenever applicable.

 However, if the primary interest really is safety on this forum, I'd never argue that the N-SSA's rules are always "safe enough" because IMO (and as of now, lacking substantiated refutation by anyone here) they don't require even a 1x factor of safety in some cases.

 Thanks much to those of you who contacted me in agreement with what I've presented.

[GGaskill]

when we here agree to the new instruction it could be sent to both n-ssa and aaa for further comments

The legal climate in the US seriously inhibits activity such as this; it would be foolish to expose oneself to liability where there is no personal benefit possible.  And I would expect that both N-SSA and AAA would reject a standard developed by outsiders because it was "Not Invented Here" (meaning not within their organizations.)

My own feeling is that scale models built with modern steels are more than adequately safe (assuming bore is same scale as the exterior dimensions or smaller .)  And a modern cast bronze barrel using 90/10 bronze or better alloy built to the same standard is also safe.

Of course, good workmanship is also part of the standard.

It's the freelance barrels that are the potential problem.

[Cat Whisperer]

Legal exposure is certainly one issue - part of the broader and most important issue of safety itself.

How does one ensure that the words written aren't misinterpreted or misapplied and jury rules against (me, you, us, ....).

I alluded to the potential compilation of a series of articles.  Perhaps a good starting point would be to accumulate a list of publications.  That would then be a place for searching what has already been published, AND might be a precursor to getting reprints of such articles published on a CD.  It would also give us an idea of what is needed.

[Double D]

Gladly, DD.

 Let's take condition HT-125 cold drawn seamless 4130 aircraft alloy structural tubing, MIL-T-6736 as an example. Strong, weldable with common processes and available from many sources (P. 116 from my Jorgensen catalog here).

Tensile - 125 ksi
Yeild - 100 ksi
Elongation - 12% in 2"

 Ideal stuff for a cannon liner. If you have any more questions, just let me know. 

 

So now would please  post the minumum ANSI standards for a 3/8 wall extruded steel tube that would not be adequate for use a a cannon liner

[Victor3]

 Just as with the 4130, any type of tubing's adequacy would depend upon the diameter of the bore and the material of the outer barrel.

[Double D]

Just as with the 4130, any type of tubing's adequacy would depend upon the diameter of the bore and the material of the outer barrel.

So provide the information using the same criteria as you used for the 4130.

[Cannoneer]

when we here agree to the new instruction it could be sent to both n-ssa and aaa for further comments

The legal climate in the US seriously inhibits activity such as this; it would be foolish to expose oneself to liability where there is no personal benefit possible.   And I would expect that both N-SSA and AAA would reject a standard developed by outsiders because it was "Not Invented Here" (meaning not within their organizations.)

I'm in total agreement with this statement. It has been suggested by some members here to ask opinions of, and offer information to the N-SSA concerning criteria for safe standards in the construction and use of reproductions of historic artillery barrels, but I just don't think this type of thing posed on their forum is going to be recieved, or responded to with anything approaching enthusiasm; so bottom line, I think were basically on our own in this discussion.     

[Victor3]

Just as with the 4130, any type of tubing's adequacy would depend upon the diameter of the bore and the material of the outer barrel.

So provide the information using the same criteria as you used for the 4130.

 There was no "criteria." You had asked...

You say that like you know what the  numbers are for extruded seamless tubing.  Would you share those numbers with us?

...and I shared the numbers. The adequacy for a given barrel's outer material and bore size were not part of your question.

 However, just as a comparison we can look at 1020 DOM (ASTM A 513 Type 5 Stress Relieved).

T - 85 ksi
Y - 75 ksi
E - 15%

 The 4130 tube with its higher strength would be adequate in some situations were the 1020 wouldn't.

 Would you agree?

[Cat Whisperer]

Hmmmm.

1018 - 1020  - 1024 -  ....  more carbon, more strength, more hardness/brittleness

then the alloys 4130/4140, only with much more strength.

The questions are of suitability for being used for cannons and cannon liners.  Now we're talking strength and resistance to cracking - both linked with DESIGN and proper manufacturing techniques.

[Double D]

  However, just as a comparison we can look at 1020 DOM (ASTM A 513 Type 5 Stress Relieved).

T - 85 ksi
Y - 75 ksi
E - 15%

 The 4130 tube with its higher strength would be adequate in some situations were the 1020 wouldn't.

 Would you agree?

Of course 4130 would be stronger.  Would 1020 be unsafe for black powder cannons?

[GGaskill]

Would 1020 be unsafe for black powder cannons?

Anything can be unsafe for cannons (or almost anything else) if not used properly.  A 3/8" wall thickness is suitable for only a 3/8" bore by itself, according to the 1:1:1 standard. 

[Double D]

We've had a good discussion on safe construction of cannon and especially on the type of liners to use in lined barrels.

Here are the safety guidelines I refer to when asked for information on how to build a safe cannon.  Nothing in this discussion has changed my mind about abandoning these guidelines. Absent credible evidence to the contrary, I see no need to abandon them. 

National Safety Rules and Procedures For Shooting Muzzleloading Artillery (These are the rules used by the American Artillery Association.)

• The bore should be lined with seamless steel tubing with a minimum 3/8-inch wall thickness and a yield strength of 85,000 p.s.i. or greater. The breechplug should be threaded and pinned; welded and pinned breechplugs can be equally strong but require expert installation by competent manufacturers. Sand-cored bores are not recommended for shooting. The vent should be drilled in a threaded copper bolt similar to original cannon vent liners of the 1840-1865 period in order to provide an unbroken passage through the casting and the liner, into the bore.
  
  
• Maximum blank powder charges for properly constructed guns of 3-inch bore or larger should not exceed 2 oz. of Fg grade or 3 oz. of Cannon Grade GOEX black powder per inch of bore diameter. Maximum powder charge for bore of more than 2 inches and less than 3 inches should not exceed a total of 3 oz. Fg or 4 oz. Cannon Grade. Use reduced loads with projectiles. (See North-South Skirmish Association regulations for a guide to projectile weights and powder charges.)
• Prepare powder charges in advance using light-weight plastic baggies with end twisted closed. Leave 2 inches of twist; cut off excess plastic. Fold twist to bag. Enclose bag in a triple layer of double-thickness heavy-duty aluminum foil (six layers total). Take care not to break plastic baggie. The bag prevents escape of powder dust and keeps granules from getting trapped under folds of aluminum to help insure complete burning. (Aluminum foil wormed out after firing often yields unburned powder although this may appear impossible to those familiar with smaller caliber guns.)

and

N-SSA National Rules for Cannons

• All reproduction barrels must be made of iron, steel or bronze. All reproduction barrels and those original barrels failing inspection must be lined with a bore liner of extruded seamless steel tubing of a minimum ANSI standard and of a minimum 3/8-inch wall thickness.
• The liner must be closed at the breech end with a steel plug, sweat-fitted into the liner and welded. The breech plug must have a radius of at least 25 percent of the bore radius and be at least 1 inch thick at its thinnest point. (See figure 10.1). All reproduction barrels manufactured after March 1, 1986 must have pictures of the liner and breech plug before and after welding. No reproduction barrel shall be approved after March 1, 1986, which does not have one caliber's thickness of metal surrounding the bore at the breech. (See figure 10.2 for example.) Liner may be affixed by casting barrel around the liner or by other approved methods such as bonding with high strength adhesives. The method of locking liner in barrel shall be approved by the Artillery Ordnance Officer. The gun and its crew must pass the inspection specified in Section 18.
• Maximum powder charges for all cannon shall be limited to that amount permitted by the chart as published below in Table 10.1. Only commercially manufactured black powder of American standard Fg granulation (150,000 granules per pound/ or 220 granules per 10 gr. wt. (avdp.) sample), or a coarser granulation, may be used. Charges must be wrapped in a powder “bag” fabricated of at least one complete layer of heavy-duty aluminum foil. TABLE 10.1 MAXIMUM POWDER CHARGES AND PROJECTILE WEIGHTS (amended 1/2005)
  (N-SSA has long chart showing both maximum charge and projectile weight for original bores size refer to Table 10.1 for those loads.)

[GGaskill]

Douglas, this is not a personal attack but a discussion of the "standards" of the N-SSA regarding muzzleloading cannon.

"Actual or exact scale replicas of Civil War artillery pieces may be fired. The term 'Civil War' applies to any artillery piece whose model antedates April 26, 1865. Replicas of artillery pieces must duplicate original pieces.  ...

... A gun crew shall consist of a minimum of 4 members of the organization. Effective 1 February 1996, all artillery pieces must be originals or full-size, exact replicas to be approved.
a. Scale replicas currently having N-SSA approval, except those with tank-type rifling, may be sold or transferred to N-SSA members or organizations and continue to be used as long as they pass the inspection at the time of transfer. If a scale replica fails to pass inspection, or is not currently inspected, it shall be disqualified from further N-SSA competition.
b. A cannon with a reduced bore is considered a scale replica gun, and is, therefore, not allowed, unless already in N-SSA use as of February 1, 1996.
c. A reproduction of a rifled cannon must be rifled, unless already in N-SSA use as of February 1, 1996."

Above is the rest of the N-SSA rule that surrounds the first two bullets above, and there is where the ambiguity lies.  They state "Replicas of artillery pieces must duplicate original pieces" and "A cannon with a reduced bore is considered a scale replica gun, and is, therefore, not allowed."  By these rules, a M1857 Napoleon would not be acceptable as its 4.62" bore would demand a breech diameter of 13.75" (3 x 4.62) while the proper diameter of a full size Napoleon is only 11" (wall to chamber ratio of .76.)  A six pounder M1841 is 3.67" bore (3 x 3.67 = 11") but the tube over the chamber is only 9.8" diameter (wall to chamber ratio of .84), also deficient according to the rules.  A mountain howitzer's chamber diameter is 3.34" (3 x 3.34 = 10") but the exterior diameter over the chamber is only 6.3" (wall to chamber ratio of .44.)  All of these are commonly fired in N-SSA events, even originals with unknown firing histories.

How do these guns fire in N-SSA events?  They have an exception--"No reproduction barrel shall be approved after March 1, 1986, which does not have one caliber's thickness of metal surrounding the bore at the breech."  [My italics.] 

It seems like the rule author(s) want safety unless you are using an original barrel.  That makes a lot of sense.  Huh?  How can a well made all steel Napoleon reproduction be a lesser piece than an original soft bronze one?  How can an underbored piece be less safe than a full bore one?

We are led to believe that the 1:1 rule is gospel; yet they must think that no one else can read prints and do the math.    They undermine their position as an authority with rules such as this.  Should it be 1:1, .84:1, .76:1 or .44:1?  All these values are OK in certain guns, all of which are 90:10 bronze.

[Victor3]

We've had a good discussion on safe construction of cannon and especially on the type of liners to use in lined barrels.

 Nothing in this discussion has changed my mind about abandoning these guidelines. Absent credible evidence to the contrary, I see no need to abandon them. 

 I'm sorry DD, but I fail to see where "We've had a good discussion..."

 I repetedly brought up several points concerning what the N-SSA considers to be safe barrel component material and construction, refuted them and received almost zero specific feedback as to why my points are invalid.

 I'll try again.

 Does anyone here believe (and please detail why do you believe) that...

1) ...a 3/8" wall extruded seamless tube of the strongest and most appropriate steel comercially available would be considered safe for all liners, regardless of bore diameter, outer material of the barrel and total breech wall thickness?

2) ...the N-SSA's incomplete description of breech plug construction (welding, fit, type of steel etc.) provides sufficient information for an accomplished machinist/welder unfamiliar with cannon construction and/or principles to build a safe barrel liner?

3) ...the N-SSA's minimum 1" thick breech plug requirement provides sufficiently safe material in all bore sizes, considering the cast iron barrels that they allow?

4) ...the N-SSA's 'grandfathered in' original CW and other older unlined barrels of less than 1 cal breech thickness that they allow should be considered safe (I can't remember how many times I've heard here that smaller barrels fitting this description should be considered "open end pipe bombs")?

5) ...we should encourage someone interested in building a safe barrel to try to decipher the ambiguous, archaic and contradictory language within the N-SSA's rules?

 If someone could please give specific point by point responses to the above, I'd greatly appreciate it.

 I never expect anyone to abandon something they've hung their hat on for many years, even in the face of logic and clear evidence. Human nature I guess, but hope springs eternal.

 

[Cat Whisperer]

Hmmm.
Yes and no.
"lead to believe that the 1:1 rule is gospel"  No. While we recognize that 'one size doesn't fit all' we've CHOSEN to err on the side of safety.

The 'rules of thumb' that we've chosen to endorse have a good safety record.  Perhaps some applications are more safe than others.

Working as an engineer, I find that we are constantly faced with problems to solve that we've never addressed before - it is a way of life.  In finding the solutions, we come up with a reasonable solution, try it, prove it.  Well, maybe the real proof is that it failed in service after a year or 10,000 repititions; so a better design is needed.  

Having a failure in a self-designed (read: designed by an inexperience/untrained mechanical/metalurgical engineering individual) is not acceptable.  Hence, our self-imposed dependance on what has been proven by long practice to work.

Other than those issues, you have good arguements.