I load a lot of sub sonic .44 "mag", 1100 fps - 1050 fps, and have had the best luck with Universal. I have also tried H110 and magnum primers when using 300gr Barnes all copper bullets sub sonic with some success - know a guy who hog hunts "professionally" with suppressed .44 mags who uses H110 and 300gr XTP's exclusively for velocities of 1050 - 1100 fps. Remember with Trail Boss that it is for lead bullets only. Some of my sub sonic loads with Trail Boss and 240 gr Lead SWC produce 800 - 900fps. I am loading some "light" .44 mags now with 300gr Nosler JSP and Titegroup that should give a little under 1100 fps - I like big bullets at lower velocities for my .44 use most of the time, shoot a lot of 335gr Hard Cast ahead of Universal sub sonic, also. The Barnes bullets and H110 are the only loads I use magnum primers on, the rest just get Large Pistol Primers.
Just my results, and what works for me. As mentioned, anytime you load light like this, be careful of a bullet lodging in the barrel.
