I had my crossbow sighted in last year with my 100 grain Muzzy's. Pretty much dead on out to 40 yards. Started practicing this year with field points and was still pretty much dead on and consistent. Switched over to my Muzzy's just to "error on the side of caution" and wow...I am all over the place. I checked the heads for being loose and everything else I can think of. I an getting 4" groups at 30 yards. Something is not right guys.By the way, I am letting my crossbow set in a led sled to fine tune it just like last year. Everything seems and feels the same.Opinions please.

wax the strings? rail? red dot sights off?

The first thing I would do is to spin test every bolt with the broadhead installed. Install your broadhead and spin the bolt point down. They should spin tightly on a hard flat surface with no wobble. I check every bolt or arrow that I shoot this way and you would be surprised at how many broadheads don’t align properly with the insert even though they thread on easily.

Thank you, I will give it a shot.

Hope you figured your shooting issue out. A fixed blade should fly almost as good as a field tip if everything else is in order. If something is off, even slightly, a fixed blade will accentuate it even more. I had the same issue. Changed up broadhead weight size and switched arrows to a different mfg and groups started coming together. I had a slight issue (still do to some extent) torquing the xbow when I'd shoot it. Flinching. Didn't realize it till my shot was put under slow-mo cam. Now I focus on more of a pull than a squeeze and that's helped straighten out my shots more than anything. The goofy recoil of a xbow can do odd things. Just be consistent.