Let me start by saying I am brand new to traditional archery. Having said that, I have not found a nicer group of guys than the folks here on tradgang. I picked up a longbow from here last sept. but because I wasn't profficient enough to hunt with it last season. That will change this year as I sold my old wheelie and there is no turning back. Okay, now to my question. I needed arrows for my bow and i wanted wooden arrows. So, i went to the harrisburg sportsmens show and found a archery shop. They set me up with awesome arrows of varying spines to see what shot best. From 50-75#. My problem is I back up to 15 yards, Stare at the vitals and shoot. The 50 and 75# Don't act great but all the others group right in the vitals. With the ones marked 57 and the other marked 70 shooting the best. My dray is 28 1/2, the bow is marked 55 @28, and the arrows i have are cut ton 30in, and have 100 grain heads on them. Shouldnt the 57 be underspined? Help!