Guess my experience are not the norm then, cause all my stuff tends to want heavier spine. The only bow I had that shot 1535 shafts well was a 45lb bear montana with 225 up front. My 50lb northern mist needed 5575 with 350 up front. My modern ilf type bows (47lbs at my draw)require mfx400 with brass inserts and 200gr tips. I leave all my arrows full length. When I bareshaft my bows, the weak arrows fly sideways. I consulted with Stew about my hoyt buffalo and his calculator indicated I could use a weaker spine then the 400's that flew where I was looking and fairly straight thru the air. Fletched arrows that look like they are flying straight, may not be. I have video showing my 1535 shafts shot out of an ilf bow that was pulling about 40-42lbs and they are flying a bit sideways, but only visible in the video.