Cannon Cry For Help

[MANITOWOC]

Good day all.
A very close friend on my is retiring and I would like to get a very special gift. He is an avid black powder collector to include small a few small signal cannons and a complete collection of Big Bang toy cannons.
I recently discovered what appears to be a cast iron cannon for sale. It's approximately five feet long. No extras with it just the barrel with touch hole and the two pivot brackets cast into the sides.
I'd guess the inside diameter is a good three plus inches. I didn't take a real good look at it when I first discovered it and I'm prepared to go back and take a better look after some advice from some of you that might respond to my cry for help.
I'll attempt to upload a picture of the item.
What further details should I look at, how much should I pay for such an item?
Thank you all for any advice you might be able to give me.

[KABAR2]

First weclome to the forum, it is hard to give you much with the poor quality of the photo which cannot be inlarged.... from your discription this may be a decorator barrel the cannon is long and thin 5ft... with a 3" bore.... wall thickness if cast iron is too thin to be a safe shooter also the trunnions look odd in relation to the size of the gun... If you can get better photos it would help.
On the otherhand it may be a section of modern breach loading cannon barrel that was demilled and later given a new life as a homebuilt muzzel loader, see it there is any rifiling.... it would explain the odd trunnions on the thing also.... need more photos....
 
Allen <><

[Double D]

You need to know what the gun is made of or how it is made.

It is the policy here to reference the safety guidelines of the  N-SSA as the minumum standards. 

One basic that is a good place to start is that the walls over the chamber need to be same thickness as the diameter of the bore.

You  say the bore is 3 inch plus, then diameter of the barrel over the chamber should be 9 plus inches  to meet the basic safety guidlelines..  (3"+ time 3 equals 9"+)

[MANITOWOC]

Great information!
Thank you both for your comments, very informative.
I'll make another trip and get a whole lot more information than what I've provide so far, along with better pictures.
Deeply appreciate the help.
Jim

[flagman1776]

Pictures!  We need pictures to give more info.  Shape & configuration helps to ID the issue.
Measure!  Measure bore, OD at vent (touch hole).  Measure length.  Trunion (pivot) diameter (corrilates to original bore diameter).  Measure length inside bore & compare to length muzzle to vent.  Sometime out of service cannons are plugged with concrete or balls wedged in place.
A light...  photos of condition of the bore. 
Some old cannons were upended in the earth as fence posts or piers as bollards.  Naturally such abuse makes restoration difficult. 
I'm presuming the barrel is probably cast iron.  Check with a magnet to be sure.
Markings.  Older tradition had markings on the breech or top surfaces.  By the era of cast iron, the marking were on the ends of the trunions.  If permissible (by owner), a scrubbie pad, steel wool, wire brush might be helpful to bring out markings.     
edit:
I didn't see the picture when I wrote this.  Indeed the image is a slender barrel with odd trunions.  May indeed be a fantasy piece.
 

[Cannon Cocker]

Interesting giant rimbases with small actual trunnions.  I would guess that it was made for a very specific carriage, or by someone not familiar with typical historic designs.

[MANITOWOC]

Okay guys, I ran out and took a better look, results as follows.
Not cast iron, steel.
Diameter outside, end of barrel is 4.5", inside is 2-3/8". Net wall thickness a hair over one inch.
Length of 52.5" outside, inside barrel is 48".
Trunion diameter of 3", length of 3.5".
Base of cannon to center of trunion is 20".
Diameter of exterior cannon at base is 4-1/4".
I'd guess it weighs in at around 120 lbs.
I took a few pictures, I'll upload tomorrow as I download from camera.
Could find no maker marks on it, will be calling the owner tomorrow for more details.
Thanks for the listen and all your help.

[flagman1776]

As others hinted, steel makes it modern.  It does not have the wall thickness desired for safety in repro artillery.  Not necessarily unsafe but makes more research important.  The trunions are not an authentic design.  I concur with above comments a modern tube possibly built up on a demil barrel.

[MANITOWOC]

Thank you all for your comments and advice. I believe I better hold my draw on this piece and wait for the return of my friend and let him take a look himself and make the move if he so desires.
Looks like I have enough rope to hang myself on this one.