After shooting my gear for 3 years I'm finding that I can really tighten my groups up at 20+ yards so I've been experimenting with bareshaft planing to check the set up on my rig.
Today I was shooting the same arrow (beeman mfx 500, 28.5 inches, 75gr insert) and I noticed no real impact in left/right hits using point weights from 150 - 225 gr. The shaft also flew slightly knock right regardless of what weight I was using. Would you normally see this sort of point weight flexibility or am I doing something wrong?
Dynamic spine calc has me nearly dead matched when using 175gr.
In my limited experience, I've been told that once you cut shorter below 30 inches, things stiffen up quick. If you are kinda in the center of the perfect spine you could get that kind of range since carbons respond quicker than wood or aluminum. I noticed little difference between 200 & 250, 175 was still slightly stiff. I noticed the real difference when I got the broadhead on. U may find the same.
On the other hand, if I snap shoot and don't find/hold anchor prior to release, I can bare shaft well with any weight and it is decieving. Do it right and results show. So could depend on how you shoot too. I don't pay attention to where my nock ends up, just point of impact. Good luck.
Some bows are very tolerant of spine changes. Try some different shafts and see if you get the same results. Your nock right flight could be a result of you torquing the bow a little, or maybe you're trying to watch the arrow flight and dropping your bow hand.
Does not surprise me at all, I think 90% of folks shooting carbon could increase their point weight quite a bit and if they think they are getting good flight now, wait until they try it and see how much better it can be!! They will be pleasantly surprised! Shawn
What kind of bow are you shooting and what's the draw weight?
http://www.acsbows.com/bowtuning.html
Although I do use bareshaft in my tuning regimen, I don't stop there with my hunting bows.
But to answer your question, No I don't find it unusual...
Carbons seem to be more tolerant of point weight changes and less tolerant of length changes.
To me, your results say that you a dead in the middle of the proper spine range for your bow.