Great shooting marrakai - I-too would like to see how it shoots a well set-up round ball load. Cast from WW alloy, they'll out penetrate the various 'slugs', including the Brenneke's.

There seems to be 2 or more different weights in Brenneke's. I've seen them listed to 575gr. - that might have been a long time ago, though.

The speeds you are getting are excellent for a 492gr. slug plus wad column.

Alan Mckenzie of this forum has also been working on RB loads for his smooth double and my Husky with right tube straight rifled has now been tested with RB's.

The nice thing about round balls, is you can adjust the weight, ie: diameter over a fairly broad spectrum and still obtain really good accuracy. The smallest I've shot in the 12 bore was .684" as I had the mould for my 14 bore rifle. I got these 480gr. in pure and 466gr. in WW up to 1,550fps with both black powder and smokeless. The normal 12 will take balls right up to 729" which is nominal for 12 bore, but most bores are oversize these days in single barrels. What the doubles run, I don't know. My double, make of fluid steel around 1900, had .725" bores.

What this means is you can adjust regulation same as with a rifle - by adjusting ball weight and charge to get the barrels to shoot together. As noted, the .684" weigh 466gr. in WW alloy but 480gr. in PB(pure) while the easily aquired Lyman .715" pure lead ball weighs 545gr. and about 535gr. in WW alloy. I've a Jeff Tanner(England) .725" mould that casts 575gr. in pure and 550gr. in WW's, and for overbored guns, there's a Lyman .735" ball that round around 595gr. and 570 in WW., so there's a spread of 466gr. to 600gr. just for the testing and regulation of loads to barrels.

The only 'trick' to getting round balls to shoot accurately, is developing some method of holding them centred in the bore - the base cup (gas check) of an used trap wad, if cup-shaped, does the trick for any ball size. One cup down over the smokeless powder and 1 cup-up underneath the ball works perfectly. Any trap range is littered with them. A pair of side-cutters does quick work on the cushion and pedals. Normal fiber wads are used for 'filling' in to get proper wad height for crimping. I like folded crimps with the ball just pushing up the folds a bit, to be visible. Others use a roll crimp and still others, use a bullet crimp with brass cases like the picture. Allan uses a couple felt-type wads with the centre cut out to centre the ball and this works well in his double. It's all about experimentation.

I'll caution about black powder loads - they kick a lot more than smokeless - and - if using plastic in a black powder load, the plastic must be isolated from the black powder or it will melt the plastic onto the bore. I used 2 card wads on the powder then the plastic cup and that seems to work. Greener's book lists 3 12 bore loads for black powder - 4 1/4 drams or 116gr., 150gr. or 5 1/2 drams and 191gr. or 7 drams. The 7 dram load shot to my sights as did the smokeless that kicked about 1/2 as much - interesting. Too, the 5 1/2 dram load also shot close enough for game shooting - about 5" at 50 yards. both smokeless and heavy black powder loads would hold in 3 to 3 1/2" at 50yards and 8" at 100 yards.

Edit to include picture. These are the loads for the right barrel of my 16 bore Husky double. The groove diameter is .703 (about 13 bore) while the bore is .671"- weak 16.- Interesting, straight rifled. The balls are .684", qwhich engrave almost 1/2 way - initial shotoing was offhand @ 28 yards - nice balmy -20 - cold and miserable, Actually, the shooting was fast and furious as I just wanted to get out of there. They made a diagram of 3" for 10 shots, the first 5 shots were in 1 1/2".