I finally got to shoot my MH Extreme today. I tried 300 grain Remington 45-70 slugs with MMP orange sabots. Results look promising. I shot 3 shot groups using 80, 90 and 100 grains of Blackhorn. Biggest group was about 1.25". Smallest, using the 100 grain load, was a cloverleaf. Tomorrow, I'm going to try the 325 grain Knight A-frames. I'm using the NFPJ breechplug. Ignition was instantaneous and the rifle was a breeze to clean. I had my doubts about Blackhorn, but now I am a believer!