Ok after making some adjustments I show the Terminator lights with a 125 grn broad head and 4 inch feathers being slightly stiff for your set up. Like I said, not a bad thing really. You could probably increase your draw weight to 65 lbs or so and have them spine well. Which is nice considering you are at the bottom of the weight range.

I was getting messed up by the fact that these are Terminator LIGHTS, not regular terminator selects. These are not in my data base. No big deal though the spine deflection is the same for either, it was just throwing my weight off is all.

As far as your difference going from 100 to 125 in speed, it won't be much and probably not as much as you think. I get closer to 233 fps instead of 238 ish. Let me know what happens when you shoot them over a chrono that way. Heck you should have slapped one on and checked it while you were there. What I can tell you is you will notice no difference in performance. The speed difference either way is not enough to effect trajectory or KE or your sight settings.

With the 125 grn head and 4 inch feathers you should have around 15% FOC which is really good for a hunting arrow. They should fly pretty darn good for you if they tune well.

If you have trouble tuning them I would look at these things. First check for contact issues with your rest or harness. Probably not a huge deal with feathers, but it is normally the first place you look. Then I would take a close look at the arrows. Spine test them to make sure they are all straight and the inserts are square to the shaft. Fixed blades need to spine very true in order to fly right. While you are doing this check the nocks as well, many don't look at the nocks, but have bad nock fit is just as bad as bad inserts.

Number your arrows and watch what they do. If you have one or two flyers all the time see if they are the same arrows. If so don't use them to hunt with, save them shooting with field points up close or ditch them.

After this if you still can't get the arrows to tune and you are confident the nock setting is good and centershot is good look at your draw weight. Try turning it up a little at a time and see if things get better.

This is providing you shoot well to begin with. Inconsitant form and grip will make it very hard to tune. What you may think is a tuning issue could be you changin the way you grip the bow from shot to shot. Or you are anchoring in a slightly different place each time. Anchor will usually show up as up and down misses, and grip will usually show up as side to side misses. Both combined will really mess you up.

Just remember don't expect to tune any better than you can shoot to begin with. And if you are not a pretty good archer expect your fixed blades to shoot slightly larger groups than your field points do. They are not as forgiving to shoot.

If you want to gain some speed the first thing I would do is change peep sights and put on a string loop. Taking all that weight off your string will help alot. It will also move get your arrows closer to the correct spine. Get a peep that does not use a rubber tube, those things suck up speed and make noise. The string loop will help align your peep for you. I like the round cheereo looking peeps myself. Or a timber line NO Peep is a good option as well.

Paul