My .69 (14 bore) smokepole made diagrams of 1 1/2" constantly at 100 meters with from 140gr. to 165gr. of 2f and a patched round ball. It's twist was 66". It would not shoot accurately at 100 meters with less than 140gr. of powder. Dropping the charge to 3 drams of 3F would open groups to almost 4" at 100 meters and fall some 5" below the line of sight. 3 drams shot OK to 50 yards, if 2" off the bags is good - not good enough for me, though. 120gr.(4.4drams) to 140 gr.(5.2 drams) for close shooting would cut a barely enlarged hole for 5 shots.

I would be happy with 3" at 100 from your double & I'm sure it wil provide.

Of course, I"d stay away from conicals if at all possible.

At 7 pounds 10, it is probably meant for 1,000fps with a light conical or better yet, due to the rifling a 'moderate" 4 dram load - 110gr. to 115gr.(or more) and round ball might be better yet. The recoil impulse necessary to regulate will be better served with a faster round ball load, than a barely moving, football-arching trajectory of a concial. In my opinion - of course. I am biased towards a round ball in bore guns. Baker's words still ring true - he had conical moulds made for his rifles, and they never gave satisfaction on big animals - he eventually "gave up the conical as useless" for killing game.

He was talking about bore rifles, of course, not the .577 BPE, which was the first conical rifle he used that would compete with his bore rifles. Due to it's high velocity with descent weight projectile, it gave enough penetration and shock. In the larger bore rifles, the conicals developed such low speeds, as to be very much inferior to round balls. Besides, round balls are much easier to cast and load for, especially when a patch can be used to make fitting perfect.

Lyman and Lee both make a .690" and Lyman a .715 as well - perfect for any sized 12 bore - with an appropriate patching. Lyman also makes a .735" ball mould, and Jeff Tanner will make you any size you want in a brass mould, for about 50% the cost of a Lyman mould. I like my Tanner moulds - sprayed with Ms Moly or Hoppe's moly bullet coating. This eliminates any sticking or soldering of hard alloys to the brass - or iron blocks for that matter. I use it on all blocks. It is a one-time application. Rapine also sells a 'mould prep' which is a graphite in a solution. You merely brush it allover the mould and let it dry. With the moly's spray the mould blocks inside and out, and let it dry - which is rapidly, heat it up and start casting perfect balls.

The Tanner moulds don't have a sprue cutter - I use 'sharpened' side cutters or a plyer's type wire stipper to snip off the sprues of those balls, then file the remaining little snip of lead off. This way it doesn't matter which way they go in, unlike balls from a sprue-cutting mould as loaded in my 16/14 bore ammo above. They could also be filed, but the ball is smaller in diameter top to bottom, than side to side due to the type of cuttoff used by both Lyman and Lee.