If you can find it r26 for the Ackley is where you will do the best. With the 26 you will get best results with br2 primers. If you want to see how your rifles does with the 156 I would get a box of Berger loaded ammo and see how they will do. You would have fireformed Lapua brass also...
Forming brass for my 260 Ackley use a load not at max, I don't shoot the 156 in mine. The 140 hybrids and r26 with br2 primers shoot unreal. I use the 156 in my 6.5 Sherman with r26 and a buddy uses magnum in his.
I clean my brass before annealing with mine, I had the same problem, after cleaning the rollers and getting all the crap off them it helped out a lot. I clean with steel pins and anneal after they are dry.
257 stw 110 accubonds @ 3700 fps, 100 gr bonded wildcat bullet @ 3980 fps, and 125 wildcat @ 3550 fps. Ramshot magnum in lighter bullets and retumbo for the heavier bullets.