13/16" barrel bored to .54?

[nathanbowenarrow]

Can a rifled .32 13/16" be bored to a .54/28 smoothie safely?

Thanks
Nathan

 

[Russianblood]

The short answer is NO. It would be waaaay too thin.

 

[Bob Gular]

I wouldn't do it. Just not enough wall thickness in the chamber area where the highest pressure occurs. There's got to be a good reason none of the barrel makers offer that combination.

 

[szihn]

Here is the math on it.
A 13/16 barrel is 812" outside across the flats.
Subtract .540 for this and we get .272
Devide that by 1/2 to get wall thickness and you get .136" (slightly more than 1/8")
Now cut dovetails into it for underlugs. They will be about .045 on the thin side and you then have a wall thickness of 091" under the dovetail slots
That's Less then 1/10 inch.
Now, if your barrel was made of a modern "super steel" like the Chrome-Moly used in a 44 magnum revolver cylinder, it would probably still be safe if it was always loaded correctly.
(You can measuer a 44 magnum cylinder and find that it's not even .091" thick, but it's made of different stuff. A 44 Mag has a top SAMMI pressure spec of 43,400 pounds per square inch, which is far higher than an 80 gr. black powder load would be in a 54 cal with a round ball)
BUT........
No barrel maker would chance it.
You see, any over load, or any air space in the load, could cause problems, and just in the interest of liability, no one is going to do such a thing. It's just not worth the risk.
If you want a very light weight 54 smoothie, get one that's Octagon-to-Round, and get it with a 15/16" breach on it. It could be turned down very light in front of the octagon. You then use solder-on underlugs in the middle and in the front, so you don't have to cut into the thin part of the barrel. Such a barrel is safe, VERY light, and will ballence far better than a smooth 13/16" full octogon.

 

.812" - .58 = .116 wall thickness

Not much room left to cut threads for a breechplug. We won't even talk about dovetails for underlugs or sights.

Getz used to make a 13/16" straight barrel in .50 but it came with warnings to soulder everything on without cutting into the barrel, even in .50 cal.

Actually, there are shotgun/smoothbore barrels even thinner than this. I saw one being fired on the Friendship trap range that was blowing smoke through pinholes in the damascas. The end of the tubes was about the thickness of a Campbells soup can.

I'm not saying it is a good idea, if it were done it would have some severe limitations. Finding someone that would do the boring and rifling for you would be a nearly impossible due to the liability.

If you want the lightest, thinist, safe .58 barrel available look for a tube intended for a rifle musket. They will be thinner and lighter than the 1" across the flats barrels from the normal suppliers.

 

[Birddog6]

Getz used to make a 13/16" straight barrel in .50 but it came with warnings to soulder everything on without cutting into the barrel, even in .50 cal.

They must still make them in 13/16" x .50 cal, as they had some at Friendship in June, but no warning was given with them when they were sold.

 

[szihn]

Oops
Goast is right. He said 58 cal, not 54 cal.
So the walls would be even less than I said

SZ

 

[arcticap]

Here's a picture of the muzzle of my Pedersoli/Navy Arms 13/16th's barrel that's .50 caliber.

 

[nathanbowenarrow]

Thanks
What I had in mind was buying a southern rifle I had found and making it a smoothie without changing the barrel. I has a single triger and it is a fair deal but if I buy it, I will leave it as is.