Agree 100% with pinsandpitons, and JohnnyC, when reloading, subsonic, or any other type rounds, ALL those that do not suggest you research your planned loads, with several (more the better) manuals, are idiots. Loading is safe, loading is fun, loading produces the best ammo. Poorly loaded ammo damages firearms more often than you think, and people too. Bullet setback has blown a couple of handguns over the years for example. A good "bulky" powder like trail-boss is a great choice for starting, (and maybe staying with). Get the books! A tip that may help you: SS rounds have similarities to pistol rounds, not just in the velocity end. As you are looking to keep your velocity below the "speed of sound" (a speed that varies depending upon the conditions), bullet weight/shape become a primary concern. You can increase weight, and seating depth, but you can't increase velocity. Bullet pull is also more akin to a pistol round than a rifle round when using some powders. Read all you can, start with KNOWN-pressure tested rounds, and go from there-because you're asking before you start-you are most likely going to have a lot of fun--good luck!