Sounds like you have so much poundage you can't pull the bow past 24". If you want a 50# bow NEVER, NEVER pull your bow past 50# while you are making it, a scale is very important in bow making, you have to know where you are at as far as the poundage goes. You may hit 50# at 15" of draw, at this point scrape off some wood, lower the poundage and increase the draw to the next point you hit 50#.
No wood bow stops at 24".