I've found that my Springfield likes the Civil War era Minie, which is a lot heavier than what you have been using. I like the 560 grain Minie best, but there is a 500 grain bullet available that is good in some rifles. Your 60 grain powder charge is equal to the standard military load and has always worked well for me. The most important thing is to use enough powder to expand the skirt on the Minie--without this your rounds will tend to keyhole and miss your target altogether. Some like load much lighter for target work, maybe down to 45 grains or so. It's worth trying if you are so inclined and will certainly save on powder costs. Always be sure the projectile is firmly seated on the powder.
