Boring a 12 Pound Napoleon Question

[Mickey_D]

I am trying to figure out the best way to build a proper full scale steel replica 1857 12 pounder.  I have enough experience with cast iron to not want to go with a cast gun with a liner, so I am either going to use 12" OD 4.5" ID 1026 steel DOM seamless hot formed tubing opened up to 4.62" with a portable boring head and with a shrunk/welded plug, or a piece of solid 12" OD 1018 and bore it out.  I can gun drill the blank to 1.25" full depth and then use that hole as a "guide" to incrementally open it up.  Anyone have a good picture of a classic style blind boring head?  I have one in a book somewhere but it seems to have gotten legs and walked off. 

[Cannon Cocker]

Having made a few full size guns, I would suggest 1018 as a material.  I would either gun drill a blind hole or if you drill it all the way through I would use a threaded plug which doubles as the cascabel.   That's my 2 cents. 

[Cannon Cocker]

One more suggestion which finishes the gun as long as we are talking design techniques.  Turn 2 tunnions with rimbases.  Countersink a spotface just past the curvature of the tube.  Weld trunnion rimbases into spotface.  Grind weld to a fillet.  Shoot gun.  Send pictures of smoke and fire.  Now I've given away 4 cents.