Barrel wall thickness

[mikeyfirelock]

I am thinking of repurposing a barrel that I’ve had for a long time but never used.  It is a 13/16 octagonal in .45 cal. And I suspect that I cut the slots for the tenons a bit   
“ generously” .   I measure them at 0.100 “ deep ( at 6 in. Ahead of breech face.)
This leaves a barrel thickness at that point that I calculate at 0.175 - 0.180 “ and I have reservations about building a rifle around this one.     Do I have a derringer barrel and 2 dueling pistol barrel at this point ?
Mike Mullins ( aka Mikeyfirelock)

[Hungry Horse]

 I had a friend bring me an old Belgium made trade gun to look at, and see if it might be in good enough shape to shoot. I took it apart and examined all the crucial parts to make sure it was safe. When I got to looking at the barrel   I found that it had a spot on the underside of the barrel that looked like it had been repaired. After cleaning the repair’,  I found that it likely was repaired after its proofing in Belgium. The small crack had been sweat brazed closed and had not created problem for the rest of the guns working life.

 So, on your gun, I would put the lug in the generous dovetail, and braze it in place. And don’t forget to give any new owner a heads up about the repair. I’m sure we won’t have to worry about you overloading it, you’ll be thinking about that lug every time you pull the trigger.

Hungry Horse

[mikeyfirelock]

Thank you, Hungry Horse.   I was on the fence about it.   I think I might still use it for a pair of pistols…….i can make a very nice pair, and still have enough left over to make miscellaneous parts as needed.   We’ll see “ which way the wind blows” down the road.  Thanks again
mikeyfirelock

[Manitou]

Pistols generally have a faster twist rate than rifle barrels.
You can make pistol barrels from a rifle barrel, but I doubt that you will get as good of accuracy from them if this is important to you.

[rich pierce]

I am thinking of repurposing a barrel that I’ve had for a long time but never used.  It is a 13/16 octagonal in .45 cal. And I suspect that I cut the slots for the tenons a bit   
“ generously” .   I measure them at 0.100 “ deep ( at 6 in. Ahead of breech face.)
This leaves a barrel thickness at that point that I calculate at 0.175 - 0.180 “ and I have reservations about building a rifle around this one.     Do I have a derringer barrel and 2 dueling pistol barrel at this point ?
Mike Mullins ( aka Mikeyfirelock)

I’m thinking of this. A 7/8” octagon barrel in .50 has .375/2 or .187” wall thickness. And people put dovetails in such barrels. Maybe my math is off or I’m not understanding the situation properly.

[Gaeckle]

I am thinking of repurposing a barrel that I’ve had for a long time but never used.  It is a 13/16 octagonal in .45 cal. And I suspect that I cut the slots for the tenons a bit   
“ generously” .   I measure them at 0.100 “ deep ( at 6 in. Ahead of breech face.)
This leaves a barrel thickness at that point that I calculate at 0.175 - 0.180 “ and I have reservations about building a rifle around this one.     Do I have a derringer barrel and 2 dueling pistol barrel at this point ?
Mike Mullins ( aka Mikeyfirelock)

I’m thinking of this. A 7/8” octagon barrel in .50 has .375/2 or .187” wall thickness. And people put dovetails in such barrels. Maybe my math is off or I’m not understanding the situation properly.

We often see these 7/8th by 50 barrels show up in our class at the Log Cabin. The students haven't grasped the concept of cutting lugs into these barrels and removing metal. We will instruct them to reduce the thickness of the lug and then install those. A simple demonstration is all it takes. Most of the lugs available are in a one size fits all size are somewhat thick and the students think that the entire thickness needs to be installed into the barrel, which is not the case. Personally I install the first lug about 10 1/2 to 11 inches from the breech

[Steeltrap]

Just doing the math here, and I seem to be missing something (maybe?)

A 13/16 barrel measures .8125 across the flats. A 45 caliber bore measures .450. That leaves a difference of (.8125-.45)=.3625. Then half of that would be the wall thickness, or .18125.

If you cut a grove .100 deep, then you have left .8125 (81-thousands) remaining.

On the matter of using a rifle barrel for a pistol, since you have the barrel at 45 cal, you could simply have them rebored to .50 cal with a faster twist. That's what I plan on doing for next winters project.

[Bob Roller]

Rifling in any barrel that is .100 deep can be classified as splines as seen in the hub of a standard shift clutch. Many barrels have been made and sold that were made from material that was NEVER intended for the pressures of an abrupt ignition of any kind of powder used to launch a projectile.Antique barrels are a gamble and if one of these blows up there is no recourse.How many modern makers of barrels dedicated to black powder have product liability insurance is not known.I don't know of any black powder barrels from the 1800's that was 13/16 across the flats other than a percussion revolver in 44 caliber.Caveat Emptor applies here.Deep dovetails for sights are another hazard that can be
a threat when enthusiasm is substituted for skill and ability to measure accurately.Making pocket pistols from these this barrel makes sense.
Bob Roller
 

[Daryl]

One of Bob's points is that typical rifling is .010" to .016" deep, not 1/10" deep.

[Manitou]

Before retiring, I spent 38 years as a toolmaker/ tool designer/ Mechanical Engineer for an electronics Corporation.
During that time I also belonged to the old, now defunct MLML (or Muzzle Loading Mailing List).
This barrel discussion came up a lot, so I made a drawing of several different barrel cross sections in different widths and their common calibers as a visual reference.
I would like to post it here if the moderators will allow.
Manitou

[rich pierce]

Before retiring, I spent 38 years as a toolmaker/ tool designer/ Mechanical Engineer for an electronics Corporation.
During that time I also belonged to the old, now defunct MLML (or Muzzle Loading Mailing List).
This barrel discussion came up a lot, so I made a drawing of several different barrel cross sections in different widths and their common calibers as a visual reference.
I would like to post it here if the moderators will allow.
Manitou

Sounds interesting. Maybe start a new post; more might see it.

[Kevin Houlihan]

Just doing the math here, and I seem to be missing something (maybe?)

A 13/16 barrel measures .8125 across the flats. A 45 caliber bore measures .450. That leaves a difference of (.8125-.45)=.3625. Then half of that would be the wall thickness, or .18125.

If you cut a grove .100 deep, then you have left .8125 (81-thousands) remaining.

On the matter of using a rifle barrel for a pistol, since you have the barrel at 45 cal, you could simply have them rebored to .50 cal with a faster twist. That's what I plan on doing for next winters project.


 A .100” dovetail for a barrel lug is excessive. I would only go .050” at the most - or even less.

[DGB]

Good morning folks,
I have been making both barrel lug and sight dovetails about .040 deep. Spelled out that is forty thousands deep. I say that because I am seeing deminsions being given here with the decimal point in the wrong place. That can lead to BAD consequences!
Regards,
DGB

[Steeltrap]

Good catch. The remaining wall thickness of a 45 cal is .18125. Subtracting.10 from that leaves .08125….just over 80-thousands.

Always check somebody else’s math. Remember, measure twice, or more, cut once.

[bluenoser]

A sanity check is always a good move that has saved my bacon more times than I care to admit.
That said - I really don't think we need to calculate our tolerances to five one-hundredths of one thousandth of an inch.  I have trouble enough holding to the nearest thou.
Just sayin

[Mike Brooks]

The first 10-12 inches at the breech are important. The rest of the length, not so much. All the pressure is gone.

[godutch]

  Sanity check please. I have a lug I'd like to go just before the start of the waist on an "A" wght. Rice Allentown in .40 cal.  I can get .090 wall thickness under that lug which is 27"  from the breach. I'm on board with Mike's comment about the press. being spent out that far but being unfamiliar with these skinny little bbls. I'm looking for a 'pat on the head' I guess since I really don't want to put heat on this barrel to solder. Your collective thoughts ?   Thanks, Fred 

[Daryl]

In TRACK'S book on English pistols, many have barrel thickness of less than .020" in the waist. One I recall, is but only .013" at that location. I found that QUITE interesting, considering most pistol charges.

[Dphariss]

I had a friend bring me an old Belgium made trade gun to look at, and see if it might be in good enough shape to shoot. I took it apart and examined all the crucial parts to make sure it was safe. When I got to looking at the barrel   I found that it had a spot on the underside of the barrel that looked like it had been repaired. After cleaning the repair’,  I found that it likely was repaired after its proofing in Belgium. The small crack had been sweat brazed closed and had not created problem for the rest of the guns working life.

 So, on your gun, I would put the lug in the generous dovetail, and braze it in place. And don’t forget to give any new owner a heads up about the repair. I’m sure we won’t have to worry about you overloading it, you’ll be thinking about that lug every time you pull the trigger.

Hungry Horse

First dovetails are HUGE stress risers. Second it could very easily crack at the bottom of the dovetail. .100 is WAY too deep for any 12L14 barrel unless extremely heavy. I have seen photos of a TC Hawken that developed a crack in the bottom of the underlug dovetail (the made them FAR too deep too, about .100”.
People can do what they like but I would always keep the shooters head between me and the barrel while it was being fired if it was impractical to move out of range to the frag.
Proofing a barrel made of 12L14  is not a “proof”. It could actually set up a failure.
AND I bet that dovetail filler if proved double powder charge, 140-150 gr of FFF and 2 balls its will show a “bulge”there with a tight patch on a short jag.
Finally just up from the breech is the perfect place to suffer hand damage if it fails in 10 or 100 or whatever shots. Cause it cannot be predicted. I would not even shoot a 1137 barrel with this damage.
If the barrel has .012” deep grooves and assuming  the bore is centered the barrel we have a barrel wall of .168-.100”+ .068” Not worth the risk. The fact that there is a stress riser involved makes it worse IMO.
Did I mention that heating leaded steels to brazing temps (way past incandescence, according the Jim Kelly (the metallurgist who IIRC used to post here now and then till the “experts” gave him $#@* and he washed his hands) is a bad idea?
Belgium made? Many of these barrels would fail English proof from my reading. AND iron, if its decent quality, is actually a better barrel material than cold rolled modern steels.

[Longknife]

I have a booklet here somewhere called "The Destructive Proof Testing Of M-L barrels" by a man named Cunningham, I think. He was manufacturing barrels at the time, can't remember the Company. He went to great lengths to try and destroy a bunch oof M-L barrels. These were the "dangerous" 12L14 barrels. He did some insane things to them, super, super, overloads , double and triple balls, multiple balls., placing multipole balls spaced apart. cutting deep dove tails, grooves and such and he had one heck of a time getting these barrels to fail even with those insane loads. ...Lk

[Hudnut]

That would have been Orion barrels.
There was a long running dispute over suitable barrel steels.  Baird?  Buckskin Journal? Buckskin Report? maintained that leaded screw machine steel was unsuitable for barrel use.  Period.  Cunningham had made thousands of barrels from this steel, and was defending the practice.  Other barrel makers used 12L14, LaLed, etc.  Lot of barrels out there.  Machines beautifully.  Tends to brittleness, particularly if there is a stress point.  There were references to "Charpy Notch" testing.  Apparently also cold temperature sensitive.
Thin barrel, large bore, dovetail notch = trouble is the concern.  Shallow dovetails, or sweated soft soldered underlugs reduce risk.
Best to err on the side of caution?

[rich pierce]

If there’s concern, solder it and you’ll never worry. No harm can come from the heat of soldering. It’s done all the time for sights and dovetails on round and octagon to round barrels. Tin the bottom of the dovetail, clean and flux the spot on the barrel, wire it in place, and play the torch over barrel and dovetail until the solder gets wet. Done.

I’ve seen extremely shallow dovetails on originals, maybe less than 25 thousandths of an inch. My gut want to practice that if you go that route.

[Hudnut]

Dovetails have been formed by cutting a shallow notch and then using a specially shaped cold chisel to raise the ends.  Deeper dovetail with shallow notch.

[Bob Roller]

I used 12L14 for its intended purpose of making screws.Jim McLemore had the right idea about barrels.He made muzzle loader barrels from steel certified for the 50 caliber machine gun and bought it from another barrel maker who had/has a contract to make 50 caliber and 20MM rapid fire cannons.No worries about a black powder barrel he made blowing up and personal injury lawyers showing up.
The barrel maker that had the contract for the 50's and 20MM was NOT allowed to have ANY non certified steels in his shop and if ANY was found he would lose the contract and a heavy fine imposed.Our son Eric does tests on screws and bolts made for our Navy;s big,new subs being built and not ONE bar of uncertified steel is allowed in that shop.Same penalties applied.Eric's tests are destructive to see what it takes to pull any bolt used apart by stretching it and results recorded with lot numbers.Structural failures in a deep diving sub IS a day spoiler
I just started to post this and saw a notice of another poster,Hudnut.He's right about a running dispute about leaded steels used for any gun barrels and I had forgotten the Buckskin Report.I have never been interested in beads,bones,leathers and feathers and good quality locks and triggers were not wanted.John Baird was a friend and is no longer alive.He had a friend,Tom Dawson who was quality oriented and made some fine replica rifles and pistols AND could reregulate a double barrel rifle by separating and reassmbling the barrels and I bought a double rifle from him,a deer stalking H&H that shot 3" groups at 100 yards and open sights.Tom was very critical of the low end parts being made and sold for muzzle loading guns and made most of his own but used locks and triggers I made and he sent plates and hammers for the Hawken locks for bench crafted mechanisms.Thank you Hudnut for reviving a dormant memory.
Bob Roller

[Mike Brooks]

Discussing the subject of barrel steels and dovetail thickness is similar to beating your head against the wall until its mush.