I got a pleasant surprise yesterday shooting the Lee .690 RB (mine are more like .685 as cast from range scrap, and 485 grains.) I found that lower velocity loads in the CB3118-12AR (Claybuster 12C1 equivalent) gave great accuracy out of my NEF Tracker II (aka "my 5 pound elephant gun") with iron sights. At 50 yards:
Now, that may not look terribly impressive, but it's a 10 shot group, and those are all of the rounds I put on paper---no cherry-picking here. No doubt, others may claim to shoot cloverleaf groups at 200 yards all day long with nothing but a bead sight, but this is a great result for me, with this gun, with not-so-good semi-buckhorn sights. Shot #7 was the flyer in the group, and it clearly sounded off/hollow; probably a wad failure, as I did find a couple cocked sideways downrange. Most of the wads held up pretty well, but that probably tells you that we're right on the edge of what this wad can support.
The load is listed on the card in the pic, but in case it's hard to read, it was 16.5 grains of e3 in a Federal Tactical Slug hull (plastic base, range pick-up) with a Cheddite primer. Under the ball was a single 16 gauge 0.135" hard card. So, this is a simple, cheap, easy load that got me good accuracy and great consistency (though with an occasional blown out wad.) Didn't have my chrono on hand yesterday, but twin loads (shot) run around 1150 fps, so still pretty potent for this little gun.
There was a little vertical stringing, which was at least partly the result of the sights, which are impossible to level, but I still had no problem hitting the 5" head and heart of the Maxi-Mo target at 100 meters, which most guys at our club can't hit with iron sights on a rifle.
I've previously reported great success with this wad for slug loads, but it continues to impress with the RBs, too. Give it a try if you get the chance.