To get a starting point with any arrow material, if you take the number 26 for amo deflection and devide it by your bow weight, in you case 50 you will come up with a deflection of .520. That formula has worked for any bow that I have ever set up and works just fine. Or if you have a deflection number that is amo, you can take that number , .520 and devide it by 26 and you will come up with a poundage of 50. This is using 125 grain points and you will have to play with length, but this formula is also for a 28 inch arrow. If you go longer, add 5 lbs spine per inch, if under subtract 5 lbs per inch.