when i tried on 48's they were a bit too snug for my liking. 52's were rediculously loose so i figured a 50 should be good. im 6'1 240lbs my chest measures a 48.7 lungs full of air. so if in a teknic a 48 is too tight and in jow rocket 52 to WAY too huge, 50 should give me the room i need around the chest and waist and yet if its a lil big its got an adjustable waist. so i figured a 50 was the way to go.