Questions about my barrel design (pic)

[barrel_envy]

Hi All

It's my first cannon barrel and I want to run it by the expert folks here :bow: before I invest muchos $$ in material and machining. The primary purpose is for salutes and occasionally gingerly testing it with a lead ball when I get the opportunity to do so safely. I want to make it a good barrel so I have lots of questions for those more experienced than I.

1) I want to make it out of brass, for the color. Is it sufficient to use the common free-machining C360 brass, or should I find a more corrosion-resistant alloy such as Naval or aluminum-brass?

2) Check out my barrel cross-section (see the picture, click for full size), does it look thick enough? I made it greater than one bore thick at the breech, and then it tapers after that.

3) Is my vent in a good location? I figure having it right at the end of the bore without intersecting the drill 'bottom' it will be easiest to clean.

4) Should I bevel/countersink the touch hole and how much?

5) I'm going with a tapped style trunnion mount. (I will attach it to the trunnion with a set screw) Have I left enough metal between the hole and the bore?

6) The yield strength for standard C360 brass is around 45,000psi, so assuming the breech is twice the cross-sectional area of the bore, I figure it could handle a breech pressure around 90,000psi (let's say 75,000 to be safe) before it would deform permanently (but not blow up... that would take another 25% increase in pressure). Is it reasonable to assume my BP charges will stay below 75,000 assuming I follow safe loads and loading procedures?

I appreciate any feedback.

Click picture for full size

 

[KABAR2]

It would be better to go with bronze for the project, brass gets brittle with age it might not fail in your life time but it may for a future generation...... Also most of the better machining brasses have a little lead added which is not a good mix for cannon.....

 

[Col. Batguano]

All materials weaken slightly with every shot. CW era cannons had a service life of something like 500 rounds for bronze, and 700 for iron, after which they were supposed to be retired from front line service. I may be off somewhat on the numbers, but you get the idea.

 

[barrel_envy]

When you say "age" do you mean number of shots fired, or passage of time? I'm not going to be shooting it that much, just test shots and then special occasions.

Also why is lead not good to have in the barrel?

 

Please clarify, are you speaking of lead projectiles? Or lead in the composition of the barrel metal?

 

[barrel_envy]

I was referring to the barrel, in reference to what Kabar2 said:

Also most of the better machining brasses have a little lead added which is not a good mix for cannon

Free-machining brass such as C360 does have a few percent lead added to make it machine better, but I don't know why that would be bad thing when the brass is used as a cannon barrel.