On the Easton charts a 2018 @ 28" weights 344 gr . Plus the tip @100 gr and feathers @ approx 15 gr total makes it 464 gr. If you are using a screw in tip the insert that will add more weight ( 18 gr )
Hope this helps.
BrianW
Easton archery guide shows them as not available for that size(2018), although my calculator does allow you to add 4 grains for one(super uni), which is the weight of the next closest 2016 bushing. Easaton now shows these as coming with full taper for nock installation under the Legacy shafts, don't even show 2018 as available under xx78 any more.