RE: experts! please explain this?
Ok for starters those bow are completely different animals. The Ally puts out more power than the older one does. TAP actually shows both arrows being too weak for the allegiance. It does not even list a Gold Tip that will work at that arrow length and your draw length and weight. I ran it with a 75/95 though and it came up way weak, as well as the 2315. Both the gold tip and the aluminum you are using are actually pretty darn close in spine.
Both those arrows spine very good for your older bowtech though and either one would be a good choice, the gold tip being a tad bit stiffer. It's not a surprise they shoot well out of that bow.
I am surprised the aluminums shoot that well out of the allegiance though being that they are actually slightly weaker than the carbons are. It might have to do with the bigger diameter and slight change in nocking point, unless you changed it when you switched from one arrow to the other (which technically you should have).
Incase you are interested these are the arrows I show working for that set up. 30 inch draw, 70 lb, 27 inch arrow (are they measured correctly?) and 100 grn tip.
Beman 300's
Carbon Express 350's
ACC 3-71's
Any easton carbon 300
And in an aluminum either a 2317 or a 2514. The 2317's would be heavier and stiffer, where the 2514's are a bit weaker, but dead on in the green and 50 grains lighter. It also lists a 2512 but it's a bit weak and they are pretty thin arrows. They are even lighter though.
I agree with the others, the laser center shot tool is a cool toy, but it really just tells you what your true mechanical center shot is. That does not mean that is the correct center shot for your set up. There are many things that determin that. Like the spine of the arrow, the type of release you use, if you use a loop or not, the amount of torque on your cable gaurd rod, your grip pressure, how you anchor to your face and that sort of stuff. It's not really going to be the same for every person. Same with your nocking point.
Are both bows set up exactly the same? Like do both use a string loop or directly off the string. If they are different that would cause a difference in tuning right there. The arrow will react differently when it comes off the string. A loop uses a much more centered and direct push on the arrow, where shooting off the string depending on the release you use may impart a slight amount of side to side movement on the string.
My guess would be the biggest issue is spine. They are both pretty darn weak. I think that maybe your particular set up on that bow matches the aluminums a bit better and that is why they shoot better. When arrows are that weak they are very sensitive to minor changes in your tune. That is why normally a stiffer arrow is more forgiving. It could be that because of the size difference in the arrows your center shot and nocking point just works out better for the aluminums. I bet if you dinked with it enough you may have gotten the carbons pretty close. Maybe
The other possibility and the most likely is that because the arrows are so weak you are seeing the difference in quality and tolerances between the two much better. Like I said, the weaker the arrow the less forgiving and more sensitive they are. This not only applies to set up, but straightness and dymanic spine as well. It could very well be that the aluminums are much closer from arrow to arrow and group better as a result. Where the carbons are not as close from arrow to arrow and they didn't group as well and responded well to tuning the nocks. When you were turning the nocks you were actually finding the high sides for spine on each arrow and getting them closer together, so the flight improved.
I bet if you got arrows closer to the correct spine they would tune easier, fly better and actually have more down range energy.
If those arrows work, they work. However don't be surprised if they start shooting different later on down the road because they are bending or because your set up changes every so slightly. They also will not be very forgiving of your form. Considering you are shooting 27 inch arrows out of 30 inch bow you are already shooting a slight overdraw which is less forgiving as well. I assume you are using a drop a way of some sort.
Good luck,
Paul