You say option number one is better, but your drawing shows a verticle vent. Would it be better if i can locate my verticle vent so i have around 1 inch away from the rear of the chamber? Wouldn't that be the same as option number one? A few people in this thread have said a verticle liner would be easier, and possibly better.
The drawing is an illustration to show how it goes in. People may say it is easier, but I have to wonder howmany have really done it.
My guess is they just laid the tapered barrel down in drill vise and drilled a hole. Their hole went in at an angle- 90 degrees to the angle of the bottom of the barrel taper as it laid in the drill vise.
In order to drill the hole perpendicular the would have had to shim and block the barrel up until the bore was 90 degrees to the quill.
Easier yes to lay it direct on the vise, perpendicular no. Definitely not easier to drill perpendicular tot he bore.
Better, how?
Also, is a stainless steel bolt the way to go for this?
Why might it be better? Because it is stainless? Not necessarily. Might even set up electrolysis and corrode in place. The cannon is not stainless, the liner is not stainless. Stainless has no magic properties that would make it useful in this application. Why bother?
Thinking, a course thread stainless steel bolt, using gasket maker to seal everything off, but what size bolt?
Check my drawings in your original post for size ideas.
Since this is a cast in place liner there could be some variations on where the liner is actually located in the cast iron, so drilling straight down will allow me to keep peeking and drill until i can see the drill bit enter the bore. that will give me my depth to the bore which i can then subtract .125 from when i drill w/ the larger drill bit that i will use to tap the hole. Fill all that up w/ some gasket maker and it should seal off rather nicely.
Why bother? Drill through and don't worry about. It is non-issue with gasket sealer.
I for the life of me cannot figure out why i would want to go through all the extra steps of angling my vent liner if i can go vertically just as reliably. I will put my vent hole 1 inch forward of the rear of the chamber though.
Actually why would go to all the trouble of shimming and blocking up you barrel just so you could get it vertical. Laying it flat on the taper will get you angle One inch is a bit far forward. Make a cartridge for your gun and measure the base thickness. Compute where the vent whole center enters the chamber so it is some where around 1/4" to 1/2" ahead of the base wad of the cartridge.
Besides the advantage of the gimlet going forward into the charge with an angled vent, and angled vent will send its ejecta to the rear of the gun into the safety zone. A vertical vent shoots the ejecta straight up and it can fall anywhere-on your carriage, barrel, down your neck, and burn where ever it lands.