Ive been having the worst time finding the right arrows for my Mojostik. Its 46# @ 28" and I have a 29 inch draw. So I figure 48lbs. All my arrows are 30 inch.  The calculators show 55-60 and 60-65 spine for my setup shooting 125gr heads. I started out with the 60-65 and they were way too stiff. I added 100gr up front and still couldnt get then to tune. So i went with the 55-60 and they still tuned too stiff. I added 75gr and got them pretty good but my groups were a constant 5 to 6 inches left. So....I raised the brace height and it got them  a couple inches right but still shooting left of where I look. Double and triple checked my anchor and its still good and tight. I ended up finally getting frustrated and started picking everything up to head to the house. I noticed I had a couple old 50-55 arrows in my box and decided what the heck and shot them before I left. BAM!  Dead center. Put the paper back up and they are showing just a tad weak....but they are shooting perfect. Right where I look. Go figure!    Would yall be concerned with a little underspined? I think Im gonna make me up a dozen and call it good. These are shooting right where I look at 10 to 25 yards.  

if it aint broke, dont fix it. long as your arrow weight is ok, I say go for it.

Yep. These are averaging 547gr with 125gr heads installed.

For me, a little weak spine has always been more forgiving to anything sloppy in my form (especially my release) than a little stiff.

Pat

If they fly fine then shoot them. We're not really doing this to try and kill paper.

a tad underspined is fine with me haha

If you choose, you can come closer to "proper spine" from being SLIGHTLY under-spined by decreasing your brace height. Let off a couple of twists on your bowstring and shoot/check repeating as needed untill you either get just where you want to be or you encounter vibration/noise in which case I would tighten back up 2 or 3 twists and check again untill it smooths out.

All 5 of my  Hill bows generally like arrows spined at the stated draw weight. Example, my 65# Wesley prefers arrows at 65-70 #. However, I shoot 29" arrows and draw a bit over 27", so I am not really pulling the full draw weight.

As previously stated, slightly underspined is o.k. As long as your gear is performing well, don't worry about what spine weight the bows prefers, just go with it.

Shoot your broadheads before you decide on spine if you are going to hunt with the bow.  They will weaken your spine alittle bit.  If they shoot well, you are ready to go.

Thanks a lot guys. I'm in the process of making up a few more in that spine with broadheads. If they still shoot good then I'm gonna leave well enough alone! Lol