Another M40 fan here. Bought mine last year. Probably my favorite centerfire rifle.
Favorite Load: 40 grain V-Max, 12.5 grains 'Lil Gun, Winchester brass, Winchester small pistol primers, OAL 1.850", Lee factory crimp die, Chrono velocity 2855 fps (5-shot avg.)
This load will shoot ten-shot groups into 1/2" or less all day long out of my gun.
Barnes just put out a 45 grain TripleShock bullet is .224. They're expensive, but I can't wait to try them.