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!

I would try a heavier head to start with. Maybe 145gr. Depending on whether your bow is center cut or not, I would guess 70#-75# spine would be a good start. If its a high performance longbow maybe 75#-80#. Of course this is provided you are drawing 28"'s. I'm sure there are others who will have better info. than me, but from what I've learned this is where I would start. Good Luck !

Thanks, and the bow is cut close to center.

Most bows, particularly centershot bows or those cut close to center, will handle a farily wide range of spines.  It's possible that the 57# arrow is incorrectly marked.  But, even though on the light side, I don't find it surprising that it shoots out of your bow.  A center shot bow is pretty forgiving of release errors.  Remember, too that you're shooting a fairly light target point.  It likely would not shoot a heavier broadhead as well.  I'd go with the heavier setup just because there will be less tinkering needed as you switch points, etc.  Good luck.