im using axis 500 standard components with 145gr tip.if i installed a brass 100 insert would this be the same as using a 245gr tip. this question is for tuning purposes?

Thats what I shoot in both the AXIS and CE.
Works just fine and allows you to shoot many BHs.
I glue mine in with Hotmelt.
No problems.

I believe it will be the same (not sure since it is technically a little further back instead of all out in front of the arrow, someone will know that), but if your arrows are shooting good with the 145 grain head that extra 100 grain is gonna make em weak...Mike

Heaver inserts might not reduce spine. The 100 gn brass inserts are about 1/2 inch longer than other inserts and a 1/2 inch of your arrow no longer flexes. It's like chopping 1/2 inch off your arrow. I've found that going from 50gn to 100gn inserts actually made my goldtips slightly stiffer with the same 300gn point. Anyone else with similar results?

Are the axis 100grain inserts 1/2" longer than standard axis inserts?  If so then I see what you are saying about that 1/2" no longer flexing.  It would be the same as cutting 1/2" off your arrow AND adding about 85grains (don't know actual weight for a standard axis insert, I'm assuming about 15grains).  Maybe the 2 would cancel each other out, maybe a tad stiffer, maybe a tad weaker.  I guess the only way to find out is to do it    (I love tinkering)...Mike

CEO, I found that out with my arrows as well.