Cal and others use it all the time.You can see some heavy 12 bore loads on YT..........using both Blue Dot and Blue................750 grains is about 1.7 oz. I have used Blue Dot in 12 ga shotguns with such loads, but that was for shot.....not slugs.....which "give" less, and can be more sensitive to the pressure pulse.............good luck, be cautious ................FWB
Thanks Cal. I have been shooting it in your friend Ron's 4 bore and was impressed. The 12 is a Reilly and has steel barrels and weighs 12 lbs. I will go slow.I have been using Blue Dot for 25 years in double bore rifles (I've even fired it in a few single shot bore rifles but I keep that a secret). There has never been published a formula for its use so after nearly 25 years of using it I have found the following to work for me: 33% of the original charge of black powder for Blue Dot when using a round ball and 25% of the original charge of black powder for Blue Dot when using a conical. Generally, regualtion on a target starting at 25 yards and out to 50 yards is good but the charge may have to be added to or subtracted from to get the best target. Of course for liability I will suggest havign the rifle checked out by a licensed gunsmith who knows double rifles. I have owned well over a dozen bore rifles, both rolled steel and twist or Damascus, hammerless, exposed hammers, top lever or under lever. The above has worked for me so well I have not sought out another powder as BD does just what I wanted.
The above said, I am now experimenting with Unique in my 8 and 4 bores (I have sold my 10s and 12s as I am liquidating most of my double rifles and loading components). Unique is showing less recoil for the same velocity and the bore shows less powder residue. I'm not done so I won't publish anything until spring or summer 2021 when my work is done.
If I remember when I checked it. It was 1 in 60.Rifling: 1 turn in 100" (approximatley 1/4 turn down the bore0 is for a ball. 1 turn in 50" (approxiamtely 1/2 turn down the bore) is for a conical. If you rifle is accurate you are on the money. But, 130 grains is a bit less than 5 drams and I would imagine in a heavy 12 at least 6 drams and maybe 7.
Should tell you I shot Ron's 4 bore on Friday with 90grs of blue dot and at 25yds all shots were touching dead center and at 50 they were an inch high and an inch apart. I think that cannon is a hoot. My friends think I lost it.Thanks for the kind words and good shooting.